Dowel mushrooms for fixing foamed polystyrene

Having enough insulation in your house is essential for both comfort and energy efficiency, particularly in the winter. Using foamed polystyrene, also referred to as Styrofoam, is a useful way to insulate your house. To keep this insulation material from moving or falling during installation, secure fixation is necessary. Dowel mushrooms become useful in this situation.

Dowel mushrooms are tiny but powerful elements used in the installation of insulation. They are also known as fixing plugs or insulation anchors. The purpose of these mushroom-shaped fasteners is to firmly secure foamed polystyrene insulation panels against a variety of surfaces, including brick, concrete, and wood. Their distinct form gives the insulation material a firm foundation and guarantees that it stays in place even when pressure is applied.

The ease of installation of dowel mushrooms is a major benefit when it comes to fixing foamed polystyrene. Dowel mushrooms can be easily installed by both professional installers and do-it-yourself enthusiasts because they are generally less complicated to use than some other fastening methods that might call for specific tools or techniques. It won’t take long to secure your insulation panels properly with a few simple tools and some experience.

The adaptability of dowel mushrooms is another advantage. These fasteners can be customized to fit different applications, such as insulating exterior walls, basement foundations, or interior spaces. To accommodate varying substrate types and insulation thicknesses, they are available in a variety of sizes and materials, so you can find the perfect match for your particular project.

Type Advantages
Mechanical Dowels Durable, suitable for heavy loads
Chemical Dowels Easy to install, good for various surfaces

The main characteristic features of Penoplex

A brand of extruded polystyrene foam is called "Penoplex." Because of its many advantageous properties, this building material is regarded as one of the best heat insulators. It should be mentioned that the air microgranules in the material contribute to its extreme lightness.

The main distinguishing features of this material

  • "Penoplex" does not absorb moisture;
  • An efficient thermal insulator, so that not too thick layers of material can be used for insulation;
  • Fire resistance. This building material is almost immune to combustion and does not produce any harmful substances arising from combustion;
  • Relative ease of installation;
  • Reliability, durability, invulnerability to various types of impact;
  • Mold and fungus do not develop on foamlex.
  • Penoplex can be used in a wide range of temperatures: from -50 to +75 degrees;
  • Service life is more than 50 years.

Types of "Penoplex"

Depending on its density, the material is classified into multiple types:

  • density 28,0-33,0 kg/m³ – used for roofing;
  • density 29 kg/m³ – for foundation treatment;
  • density of 25 kg/m³ – for working with walls;
  • density 25,0-35,0 kg/m³ – universal Penoplex;
  • density 45.0 kg/m³ – industrial use.

Universal polystyrene foam is most frequently used in construction because it combines all the best features and can be applied to any part of a wooden house.

Double insulation when used and realized

Adhere the first layer, then place the second layer with offset joints on top of it.

The most comfortable conditions within the room are offered by this option. Generally speaking, this technology is advised to be used in order to complete the balcony’s living space arrangement.

Simultaneously, the bearing wall and the parapet need to have two layers of thermal insulation applied to them. It is sufficient to use one standing insulation for the floor, ceiling, and side walls. The most common materials used to implement this method are penofol and penoplex, which are modern materials.

Although each type of insulator is independent, their combined efficiency is higher. First, one of the methods listed above is used for fastening. After that, the foam foil is used. Either staples or an adhesive substance are used to secure it.

Process of wall insulation with Penoplex from the outside

  1. To insulate a wooden house "Penoplex" outside with your own hands, you need to start with the preparatory stage. First you need to level all the walls, get rid of bulges and roughness on them, otherwise then when you press on the insulation, it can break down.
  2. Then it should be obligatory treat the walls with primer. Insulation boards have a smooth surface, so to adhere the mixture well to them, their surface should be treated with a special roller for drywall. A brush or knife can also be used for this purpose. Before starting work, all slopes and window sills should be firmly fixed.
  3. Performing insulation of a log house with their own hands from the outside "Penoplex", you need to install the purlins. It should be organized using wooden bars (25×50, 50×50), or metal profiles can also be used. This stage is very important when insulating a wooden building from the outside with "Penoplex" and is necessary for fixing the heat insulator. To "Penoplex" firmly installed in the openings, the size between the bars or profiles should be made five centimeters smaller.
  4. When the preparatory stage is over, you should move on to gluing the insulation. Two spatulas are needed for the work: the small one applies the mixture on the big spatula, and the big one is used for working on the wall surface. If the walls are even, then you can apply a thin layer, if not very even – then it is better to apply the mixture in small piles, as in the photo.

Adhesive application process

It is possible to apply glue to the "Penoplex" sheets as well as the walls. Of course, it works better on the walls because of their rougher surface, which will aid in the proper adhesion of the polystyrene foam sheets. Press the heat insulator firmly against the wall after applying the glue. It is required to wait for the glue to fully cure, which takes at least three days, after the penoplex is glued.

The process of fixing the "umbrellas"

The insulation needs to be nailed down after adhering. The boards need to be fastened to unique dowels, which are disc-shaped umbrellas. These are plastic or metal dowels with big flat surfaces. Using plastic ones is preferable because they are less expensive and won’t draw in cold air like metal ones do. It’s not necessary to purchase extremely inexpensive ones, though, as they will bend with use.

Using dowels to fix (1 variant)

Dowel fixing (2nd version)

  1. So, it"s necessary Drill a hole for the dowel. The depth of this hole should be greater than the fungus by two centimeters. To calculate the necessary length of fungi, you need to add to the thickness of the heat insulator five centimeters in the wall and one centimeter on the layer of glue. Most often for one sheet of foamlex it is necessary to use 6 dowels – umbrellas, but if necessary, you can use more. There are several ways to arrange them (shown on the photo). But it is better to use the second option. Next, it is necessary to insert the dowels into the prepared holes and hammer them in. The cap must be at the same level as the foam plex.
  2. Next, when all the sheets will be nailed, it is necessary to check and treat the joints. Gaps at the joints larger than five millimeters should be filled with construction foam. If the gaps are quite large (more than two centimeters), then it is necessary to insert additional pieces of penoplex into them. Then it is necessary to wait until the foam dries. Usually it takes about five hours. Unwanted dried up pieces of foam should be cut off.
  3. After all the work done, it is necessary to carry out wall finishing. First, you need to carefully treat the walls with primer, and then thoroughly grind with an emery cloth. The leveling layer should be about three millimeters.

Before the leveling layer, all of the work that is outlined in stages is completed. Following this final layer, the walls are primed and grouted. The insulation is deemed finished after that. By using the above-discussed advice, you can insulate a wooden house with foamlex from the outside on your own, without hiring experts. The most important things are to want to do it yourself and to have a little patience.

Tips on the use of polystyrene foam

It is advised to insulate behind the heating devices when applying polystyrene foam to insulate the walls, since the walls in these areas are somewhat thinner than the surrounding surface.

Polystyrene foam can be installed using the following methods: dowels, mastic, cement mortar, and glue.

The following methods can be used to attach polystyrene foam when performing the external type of thermal insulation of walls:

  • by means of glue;
  • with cement mortar;
  • with special mastic;
  • with the help of mounting devices.

Any non-combustible material should be used to protect the insulation material when it comes to external wall insulation. Bricks, different plasters, ceramic tiles, steel profiles, and so forth are all options.

Polystyrene foam can be used to insulate a building’s foundation. When building a monolithic foundation, this material is taken into consideration; in this scenario, polystyrene foam will serve as a fixed formwork. The amount of building materials (concrete, reinforcement) that are consumed can be readily decreased with the use of this material. Furthermore, the lifespan of reinforced concrete walls and basement walls is increased by the use of polystyrene foam.

Returning to the contents table

Fastening of foam plastic

Use foam plastic to insulate the walls; this is a fairly common technique. As we’ve already established, glue is typically utilized for its fixing, but dowels are also frequently utilized for extra fixing. Let’s examine two installation scenarios.

Fixing foam plastic with glue

Finding out how level the wall that will act as insulation is the first thing you should do. This depends on a number of factors, including how the glue is applied. Using a trowel, apply the glue mixture to the wall itself if the surface is uneven; if the surface is flat, apply the glue to the insulation. Plastering should be done to even out any heavily piled bearing surface.

If you are too lazy or cannot afford to do this, I suggest switching to mineral wool instead of insulation; in this instance, surface evenness is irrelevant.

Assuming that the wall in our hypothetical home is roughly level, we can now move on to the installation process. Empty and prime the wall, fill in any chips and cracks, and remove any dust and debris.

A support strip that is the same thickness as the board must be fixed at the bottom of the wall while the primer dries. This is required to prevent the boards from slipping under their own weight. Once the primer has dried, knead the glue according to the directions on the package, as previously mentioned.

Apply the glue on the inside of the insulation by rolling it with a needle roller. Don’t leave any glue behind; it should be left in five places, with enough mass between each point and in the center and corners. Next, begin mounting the foam plastic, working from bottom to top, and hold each slab for a minute or so to let the glue dry.

Additional fixing with dowels

Should the insulation be fastened to the wall externally and heavy materials such as cladding be applied to the wall later on, dowel umbrellas should be used to further compress the foam plastic against the wall.

Nothing difficult to do here; simply drill five holes in the wall where the glue was applied after the foam has had some time to solidify. In other words, in the middle and the corners. After that, hammer the fixing plastic nails into them and press the "umbrellas" into place.

Fixing Foam Plex

Penoplex has a variety of fastener types that enable you to use the material in any system. Dowels, mastics, foam, and dry mixes can all be used for fixing. Make sure you understand your system’s structure, whether the Foam-Plex will be exposed to external dynamic or static effects, and whether you want the boards to function as a waterproofing system before choosing the fasteners.

  • Masonry mesh
  • Bituminous mastic
  • Dowels and sleeves
  • Bitumast glue (Bitumast)


A polypropylene dowel with a broad head and a metal or plastic nail is called a "mushroom dowel" or "dowel bar." used to firmly attach boards to brick bases, aerated concrete, and concrete. Six pieces are consumed per square meter. The plastic nail is not appropriate for high-rise building facades; instead, it is used in systems where there is a slight tear-off force on the board.

Adhesive mastic

Adhesive mastic is a thick mass, similar to bituminous polymer paste, that does not slide off vertical surfaces. The mastic is applied in strips that are at least four centimeters wide or dotwise (10 pieces per 1 m2) to the prepared substrate. Consumption on average: 0.5 to 1.0 kg/m2. It is possible to use the mastic in rooms with good ventilation. It has solvent and petrochemical products in it.

Glue (dry mix)

A dry mixture with exceptional adhesion properties to Foamplex, concrete, aerated concrete, and brick is the glue used to fix Foamplex boards. The prepared solution is applied pointwise (5–6 pieces, diameter 8–10 cm) in the center and in a strip measuring three centimeters along the slab’s edge. When mortar is applied correctly, 40% of the adhesive surface will be exposed. The adhesive layer should be between 15 and 25 mm thick.

Mounting foam

TYTAN STYRO 753 adhesive is a great substitute for loose adhesives. Use drastically lowers the cost of installation and transportation. It is widely believed by builders that Penplex can be precisely fastened to any base using regular assembly foam, which is less expensive than dowels, mastic, and specialty glue. Actually, mounting foam isn’t meant to be used for fixing anything because it can’t support the weight and deteriorates over time. Therefore, Penoplex should only be glued to the assembly foam if the completed system permits the use of detached boards, as in poured floor systems.

Fixing Penoplex on the basement and facades of buildings

Rules and recommendations for foam plex installation

Foam plex can provide effective thermal insulation, but only if the installation technique is followed. A level surface is used to install sheets. A starter strip composed of a wooden bar or perforated metal should be fixed first. The width of the insulation material and the strip should match in width. There are ready-made kits that include an inner and outer corner, as well as a strip, that are installed at joints.

The following steps are taken in order to install the starter strip:

  • A horizontal guide is marked along the perimeter of the building with the help of a leveler or chokline.
  • First, the required level is set, then the beacons are set with a thread.
  • On the outlined guide is mounted on a dowel bar.

The starter strip, which takes installation geometry into consideration, will guarantee that the foam is properly fastened.

Installing insulation is best done in a chessboard pattern, starting from the starter strip and working your way up. The inner side of the insulation is coated with the adhesive composition, and the assembly foam—which is free of potentially dangerous materials—is used to fill in the spaces that result.

The decorative surface finishing process is carried out following the completion of the foam plex installation.

The search for energy-efficient homes must focus on developing efficient insulation techniques. The use of dowel mushrooms as a creative way to fasten foamed polystyrene insulation is gaining favor. These dowel mushrooms give the insulation material a strong anchor, preventing it from moving around too much. They bond the insulation firmly to the house’s surface and are simple to install. They provide a dependable choice for long-term insulation solutions due to their resistance to a variety of weather conditions. Dowel mushrooms are a sustainable and long-lasting addition to insulation projects that help homeowners make their homes more energy-efficient.

Peculiarities of fixing to different types of walls

Although the materials used to construct houses and commercial buildings differ, wall insulation technology is present in both.


Sharp height variations and other irregularities in the rough brickwork make it difficult for the foam plex to fit tightly and firmly on the glue. Consequently, experts advise combining several fastening techniques:

  • mounting adhesive;
  • liquid nails
  • dowels;
  • self-tapping screws;
  • cement mortar;
  • mounting foam.

It is necessary to prime and prepare the rough base prior to installation. Use a perforator to drill holes for dowels.

It is advisable to use a combination of techniques, such as glue and dowels, to secure the foam to the brick wall.


It is preferable to insulate wooden walls from the exterior in order to prevent excessive moisture build-up and room reduction. The drawback of foam plex insulation is that it causes walls to stop breathing. Wood undergoes changes in dimensions and maintains its instability throughout the year due to variations in temperature and humidity. A wooden house should show signs of shrinkage after at least a year.

The base needs to be prepared by using a planer to level the surface, caulking cracks, and impregnating it with fire retardants and antiseptics.

A two-component glue is used for fastening, and even after it dries, it maintains its elasticity, preventing the sheets from coming off when the wood expands due to temperature changes.

Self-tapping screws are also used to secure the sheets. The insulation panels are placed inside the purlin cells if finishing the facade with a frame is the plan.

It is advised to install external insulation on wooden walls.

Block walls

It is not advisable to leave gas-block walls open as they will absorb moisture and become damp. It is required to apply an impregnation to the wall prior to insulation in order to minimize glue consumption and reinforce the base’s structure.

If the wall is not level, the protruding portions can be removed using a drill equipped with a chisel attachment. If wall panels are the preferred finish, fixing is done on the battens; if frameless cladding is the plan, fixing is done on glue and dowels.

Prior to applying the foam, the block wall needs to be impregnated with a special substance.

The boards’ joints should not line up with the technological joints; instead, each row after that should be joined with an offset. Adhesive compositions containing harsh chemicals that could harm the foam plexus should be avoided.


The substrate made of concrete is extremely absorbent and porous. In this instance, adhesion is low and glue consumption is higher. Applying an impregnating primer to the concrete will solve this issue. It will seal in micropores, fortify the material’s structure, improve adhesion, and preserve adhesive compound.

Dowels are used to secure the insulation more firmly.

Penoplex sheets are stacked with offset joints to prevent moisture from penetrating the concrete.

Price for Fasteners

Adhesive mastic Price, rubles
Gluing mastic TN #27, bucket 21.5 kg (consumption approx. 30 m2) 1720
Gluing mastic TH No. 27, bucket 12 kg (consumption approx. 15 m2) on request
Position Diameter/length Price in rubles
Insulation dowel with plastic. rod 10х80 2,6
10х90 2,7
10х100 2,9
10х110 3,2
10х120 3,3
10х140 3,6
10х160 3,6
10х180 4,5
10х200 4,9
Position Diameter/length Price in rubles
Fasteners for thermal insulation with a diameter of 10 mm with a galvanized steel rod with a thermal cap 10х80 6,0
10х100 7,1
10х110 7,5
10х120 7,8
10х140 8,5
10х160 9,6
10х180 10,6
10х200 11,7
10х220 13,5
10х260 17,2
10х300 21,2

Randol with a thermal cap to secure thermal insulation to a wooden or metal base.

Advantages of mushroom clips

Fungus-based fasteners

Specifically designed fasteners with wide flats are used when installing thermal insulation. They are known as fungi or umbrellas as a result. They work well for securing delicate materials like mineral wool, foam plastic, and polystyrene foam. You can affix the entire insulation structure to brick, concrete, cinder block, and other materials with their assistance.

Low-pressure polyethylene is used to make the dowel itself, while metal or polyamide can be used to make the wedge.

  1. The wide flat cap securely fixes any insulation material. It is rough on the inside, which creates additional fixation. If necessary, you can use an expansion washer, which increases the diameter of the pressing from 60 to 100 mm.
  2. The long leg allows it to withstand large load-bearing loads. The fixing is reinforced by the spacer zone, which consists of three sections.
  3. Plastic dowels are a replacement for outdated wooden plugs. The first do not succumb to rot and mold formation, plastic does not deform under the influence of temperatures, artificial material is cheaper than wood.
  4. Secure fastening is provided by a wedge, which spreads the anchor simultaneously in all directions. This provides greater grip on the work surface.

Apply the adhesive

There are thorough instructions for both preparation and application on the adhesive’s packaging. It will guarantee both the outcome and a comfortable working environment. Enough thickness and plasticity should be present in the final composition. It is not required to dilute a significant quantity of glue. It cannot be applied because it thickens prematurely when it comes into contact with air and evaporates moisture.

As you get to work, get the following equipment and supplies ready:

  1. Perforator or electric drill;
  2. A mixer for thick mortars;
  3. Glue container;
  4. Water;
  5. Wide, narrow and toothed trowel;
  6. trowel.

Dust and lightly moisten the wall before attaching the polystyrene foam.

Apply a layer of one to three centimeters, depending on the surface quality, on the wall. We use varying width trowels for this purpose.

If there are significant irregularities, use a thicker glue and apply it in a broken line on the foam board.

If the wall is level, we apply the adhesive mixture to the insulating sheet in the middle and all the way around. Applying to the wall and then pressing the foam board into place is a more dependable and practical approach.

If the siding installation is done in between the siding batten rails, glue is applied to the center and around the edge of the sheet on the sized boards.

A toothed trowel works best for leveling the mixture. Foam plex is laid in the same manner.

Increase reliability

It is advised to perform combined board fastening no later than two to three days following glue. Other than that, there is no difference in the fixing technology.

It will be necessary to work with:

Consider the thickness of the board when choosing the dowel length for foam plastic. Without considering the finish, the fungus’s foot should be at least this deep into the insulated surface’s material:

  • 40 mm for concrete;
  • 80 mm for brick;
  • 120 mm for hollow bricks and porous materials.

Using a plastic or metal spacer rod aids in securing the fungus firmly. Better if it’s made of plastic. The better part of it? less expensive, less durable, and less heat conductivity than a metal rod.

Dowels for attaching foam should be installed 1-2 mm below the front surface’s level. This will guarantee that plastering the polystyrene foam insulation will be convenient.

Cut one of them about halfway down the rod to create a recess for the fungi. Take the screwdriver or drill and insert the cut fungus to be fastened. The foam should then be chosen to the necessary depth in the planned installation location.

Consider the finish, insulation thickness, and depth of entry into the wall material when determining the drill length for the perforator, leaving a 20 mm reserve. The drill’s diameter ought to line up with the "umbrella cane’s" outer diameter.

It is not necessary to attach with a dowel to the wall and then to a sheet of foam plastic. All materials are drilled simultaneously in a single pass.

Drill the hole, insert the dowel by hand, and hammer the expanding rod into place.

Apply the remaining glue to the foam plastic’s surface in the depressions created by the installation. Subsequently, we primed the foam plastic and installed reinforcing mesh in preparation for plastering.

When applying the facade plaster, fixing the foam with dowels will give the structure the necessary strength. It is not required to reduce their quantity. It should be considered in the calculations that one insulated square meter needs six umbrellas. It is preferable to locate the installation locations at the sheet joints, as this will enable you to firmly press the board edges and fix two or three adjacent boards at the same time.

Use the same cautions that apply to foam plastic when handling it.

We consider every aspect before settling on a method of attaching foam boards to the vertical wall. This will enable you to complete high-quality insulation with the least amount of money and effort.

Another intriguing nuance regarding fixing with mushrooms is demonstrated in the video below:

Preparing the surface for laying

Only level, treated surfaces can be used to attach foam panels.

Such operations are included in the preparatory stage:

  1. The surface is carefully inspected, after which all contaminants, remnants of old destroyed coating, delaminations that will not withstand the load of insulation are removed. Scrubbing the walls with a metal brush
  1. Particular attention is paid to surface lesions with mold and fungus. The damaged area is cleaned with a stiff brush, and then treated with a special composition, which is made at home on the basis of copper sulfate or purchased in the trade network. Prepared compositions against fungus and mold
  1. To eliminate irregularities, a map of problem areas is drawn up. After that, the leveling is performed by any of these methods:
  • Plastering is a simple and reliable method. The mortar is selected individually according to the surface material. Insulation can be attached when the plaster dries;
  • Laying panels of different thicknesses is a labor-intensive method that requires accurate detection of irregularities. Foamlex brand depends on its thickness. When buying choose boards of different thicknesses, but the same brand;
  • The use of pads is a method used only by experienced installers. As linings, pieces of foamlex or plastic are used.
  1. Metal parts, which are planned to be covered with boards, are treated with anticorrosive compositions. WEICON Zinc Spray anti-corrosion compound
  1. Mount brackets for the equipment that will be hung in the future, for example, air conditioner.

Mineral wool

Because mineral wool is a relatively unique material, artisans must wear extra skin and respiratory protection when working with it. It can be secured using glue or, in the case of many, a specially made batten, which may not work as intended.

The purlin in question ought to be completed along the full wall, and the wooden bars or metal profiles that are typically utilized in this procedure must inevitably be positioned at a lesser distance than the mineral wool boards’ width.

The installation of mineral wool on the glue for the wet facade beneath the plaster and the ventilated facade system are the two primary uses for the battens.

Ustr-vent teploizolyaciya fasada3

It is worthwhile to think about slab mineral wool separately. The truth is that this kind of material is securely fastened to the walls not just with the aid of a batten but also, and without any issues, with the aid of glue and extra fixation with a metal dowel.

How to use glue on minwool

Not everyone is able to estimate or understand how to fasten insulation to a wooden wall without the aid of a batten. Foam plastic and mineral wool fall under this category as well. It really couldn’t be any easier: the same glue is applied, the plastic dowel is bit off to leave just a hat, and a self-tapping screw is inserted to further secure the heat insulator to the wall.

Calculation of dowel length and fixing pattern

Repairing the dowel

The length of the dowel must be precisely calculated in order to fasten the insulation to the wall securely. This can be achieved using the formula L=H+I+K+W, where:

  • L – the final result of calculations;
  • H – thickness of insulation;
  • K – thickness of the plaster or adhesive on which the thermal insulation is fixed;
  • I – anchor recess depending on the material of the wall, but not less than 50 mm;
  • W – allowance for the curvature of the wall.

It’s important to think about an example in order to determine how long to take fasteners. If the wall is sufficiently flat and you use foam that is 30 to 50 mm thick with a 5 to 10 mm layer of glue, then a 100 to 110 mm dowel will do. When choosing the length of fasteners, it is necessary to consider surface misalignment up to 5 cm. You will need to take a 210 mm dowel if you decide to use insulation up to 10 cm thick.

The mushroom fastener should penetrate a wall composed of hollow materials by 8 to 10 cm. Longer does not always equate to greater reliability. It’s also necessary to consider the wall thickness. For instance, because apartments are not very large, an improperly sized dowel may stick out from the back.

The insulation can be fixed in a few different methods. It is thought that fastening on five or six mushrooms is the most dependable fixation technique. Four are driven home in the corners, recessed 5–10 cm from the border, and one or two in the middle. A variation in which the dowel is driven at the intersection of two boards is occasionally employed. Thus, one umbrella’s hat can support three slabs at once. Every board also has one fastener hammered in the middle of it.

Sometimes, to save money, the insulation board is fixed with only 1 dowel. This option is possible only for foam plastic, provided that there is no cladding. For mineral wool, this method is not suitable, because it tends to gain moisture and, accordingly, increase its weight. The height of the insulation fixing should also be taken into account. If the foam plastic is at a height of more than 8 m, it is necessary to fix 7 dowels per 1 m². When the height exceeds 20 meters, 9 fasteners are used for foamlex. Such a number is due to the increased wind load on the building and the pressure of the upper rows of thermal insulation on the lower ones.

The insulation is usually fixed to a blind wall using 5–6 dowels spaced 50 cm apart for every 1 m². Extra fasteners are positioned at the parapet, in the building’s corners, and around the edges of openings at expansion joints. In this instance, the step is 300 mm.

Methods of insulation

Exterior insulation for the house

It is crucial that thermal insulation be achieved from the outside as well as the inside of the building using penoplex. However, empirical evidence indicates that the external insulation of the home is better for several reasons:

However, empirical evidence indicates that the house’s exterior insulation is better for several reasons:

  1. Insulation on external walls will last longer, as it will be better ventilated.
  2. The external structure will not only serve to insulate, but also protect the walls from negative natural factors.
  3. External thermal insulation will not reduce the internal living space.
  4. The work can be carried out in the inhabited house, without disturbing the internal structure.

Methods of fixing

The ease of installation of foam plex is one of its primary benefits. Any skilled craftsperson can insulate a wall, ceiling, or floor made of any material and shape. There are various methods for fixing the sheets both inside and outside the structure.

With purlins

This method necessitates the construction of a unique frame; alternatively, you can use the opportunity to install the insulation between aluminum profiles or wooden strips when installing wall finishes on the battens. To minimize the amount of cut-offs in this situation, it is best to match the sheet’s size to the spacing between the frame’s components.

To fix the sheet on the wall, assembly foam is simply sealed around the perimeter and foam is laid in the gaps. Finishing materials such as wall panels, siding, or block homes are placed on top of the insulation.

Installing the cladding over the thermal insulation is required.

On special compounds

For frameless foamed plastic fastening, a unique cement-based adhesive is available; it can be used for both foamed plastic and mineral wool. It is sold in paper bags in dry form that has been diluted with water. Liquid nails, bitumen-polymer mastic, or adhesive composition can all be used in pressurized cylinders. It is put into a foam gun and sprayed on the sheet in a crosswise and zigzag pattern or all around. Smooth sheets should be rolled using a needle roller because the reverse side of the panels has a grooved surface for improved adherence.

The frameless method of installing foam plexes can be accomplished with specific adhesive compositions.

To prevent heat leakage, foil tape is used to seal any joints where the panels are loose. The master has one hour to make any necessary corrections or remove the layer before the glue sets. The lower portion of the insulation is placed on the starter strip, which is firmly positioned horizontally, to stop it from sliding down.

On special fasteners

The sheets are fastened with special dowels that have wide dowel pins. One sheet contains five or six pieces. The wide flat cap of the dowel does not harm the polystyrene foam and offers dependable, long-lasting fastening. This technique works well for uneven walls and large spaces.

Wide flat cap that won’t fall into or harm the insulation

With a perforator, the holes in the rough base are drilled. The dowel needs to be at least 100 mm long. The insulation is frequently packaged with self-tapping screws in the necessary size.

It is preferable to apply more glue at the sheet joints and cover the joints with foil tape. The loose fit of this fixing encourages the growth of fungus beneath the foamlex layer. The rough base is impregnated with a fungicidal compound in order to solve this issue.

Fixing the insulation

Fixing foam plexus techniques vary depending on the kind of surface the insulation is applied to and how it is used.

Two requirements must be met in order for the foam to be fixed to the wall correctly:

  • Select adequate for the given situation fastening material;
  • to set the starter strip on a horizontal level for the first row of insulation.

The most popular materials for fastening are:

  • mortar from dry cement mixture;
  • bituminous mastic;
  • assembly foam;
  • liquid nails;
  • plastic dowel fasteners.

One possible initial strip use is:

  • wooden bar;
  • wall profile for plasterboard;
  • a special perforated profile for foam plex with external and internal corners (the width is selected according to the width of the insulation).

Based on a specific technology, the foam inside the room should be fixed to the wall.

Installation stages

Panel installation is completed in phases:

  1. Horizontally and vertically align the wall surface by applying plaster, putty and cutting down protruding places with a perforator;
  2. After the leveling layer dries, the wall is primed;
  3. On each mounted board "Penoplex Comfort" glue is applied, then the product according to the pre-marked markings is installed on the wall and fastened with dowel nails at the rate of 4 per board. Corner panels, if necessary, are trimmed with a knife, saw or jigsaw;
  4. The next line of panels in relation to the previous one should be installed in a staggered order, avoiding the coincidence of seams;
  5. After completion of installation, all joints should be filled with assembly foam, glue the joints with tape and cover the insulated wall with foil vapor barrier polyethylene;
  6. Finishing materials are not fixed directly on the foamplex. To install plastic panels or MDF on them, wooden or metal guides are mounted beforehand. Wallpaper can be glued only on the pre-installed plasterboard.

The same guidelines that apply to internal installation also apply to attaching foam to a room’s wall from the outside: materials may only be fixed to a level surface. The following is added to the leveling process in consideration of the external climate influences that may affect the insulated wall’s adhesive bond:

  • removal of dust, dirt, salt deposits, particles of peeled facade plaster from the wall surface;
  • solvent flushing of oil and paint stains, preventing the adhesive from being absorbed into the wall;
  • elimination of mold and fungal deposits with building antiseptics;
  • anti-corrosion protection of metal parts on the wall;
  • fluting of perfectly smooth surfaces to improve adhesion of the adhesive.

Additionally, the light fixtures, air conditioner, satellite dish, house address plate, and other external features are installed on the wall using the guide profiles prior to the foam plex installation.

Varieties of dowels

Varieties of dowels

Three categories of fasteners exist:

  • with polymer nail;
  • metal nail;
  • metal nail with a thermal head.

Plastic dowels are made of nylon, polyamide or polypropylene. They have low strength and price. They are used for fastening to concrete, brick or other hard surfaces. Plastic dowels are not suitable for fixing on hollow walls or foamed concrete. The thermal conductivity of this type of fastener is 0.004 Watt/K, which allows it to be used at temperatures of -40°…+80°С. The length of the umbrella is determined by the sum of the thickness of the insulation and the height of the spacer. Plastic dowel can withstand a load of 20-320 kg, which allows to fix mineral wool or foam plastic qualitatively. However, such a fungus is not able to withstand the weight of heavy cladding material.

Metal rod fasteners have a higher heat conductivity than plastic ones, but they are stronger. The formation of cold bridges during use lessens the efficiency of thermal insulation. Additionally, the rust from metal nails causes yellow stains on the plaster. Selecting galvanized rods with a unique anti-corrosion layer will help you avoid this. The insulation layer as a whole will have a longer service life as a result. The spacer element has a diameter of 4-8 mm, and the dowel can withstand temperatures between -55° and +60°¡. There is a 750 kg maximum load-bearing capacity.

These fasteners typically measure 200 x 10 mm. Because they can tolerate a thick layer of cladding, they are typically used for thermal insulation of facade walls and ceilings. The appearance of gaps that allow cold air to enter the room is the only drawback.

Metal nails can be replaced with fungi with thermal heads for insulation. They are made up of a steel rod with a low-thermal conductivity metal covering its cap. Impact-resistant polyamide is typically utilized for this application. A polymer composition completely coats the nail to keep it dry and safe. Polyamide has a thermal conductivity of 0.027 W/mk, which is similar to foam and mineral wool. When installing insulation, this establishes whether or not there are cold bridges. The product’s high cost can be viewed as its lone drawback.

There are various possible dowel lengths. On the market, there are three sizes:

  1. Fasteners with a length of 120 mm, which is used in solid monolithic bases. It holds the insulation well on a wall made of concrete or full-body brick.
  2. Dowel with a length of 140 mm is suitable for installation in loose material. This can be walls made of aerated concrete, hollow brick, cinder block, etc.
  3. Fasteners with a length of 160 mm are used for hollow materials. Such a dowel provides adhesion to the inner parts of the wall, avoiding the void.

Additionally, threaded anchors need to be hammered into the wall. These materials are used to make them:

When installing insulation, metal dowels are used if a thick layer of cladding is to be installed. One can categorize plastic fasteners into:

  • polypropylene;
  • nylon.

When installing acoustic boards, thermal insulation between concrete, soft tiles, roofing felt, etc., roofing dowels are utilized. They include:

  • 50 mm diameter caps;
  • fiberglass rod;
  • anchors.

Types of fastening

After analyzing the feasibility of covering a wooden house with foam, we concluded that this is a recommended option when the ventilation system is of a high caliber. Let’s now talk about how to attach the sheets to the surface.


Here are the instructions if you want to complete the work with your hands:

  • First of all, a frame is attached to the surface, in which the insulation will be located, the width of the spans should be 5 mm less than the width of the sheets to insert them tightly.
  • Sheets are placed from bottom to top, if we are talking about walls, or from any convenient side, if the ceiling is treated. After finishing the work it is necessary to check the surface for joints and gaps. If there are any, they should be sealed with polyurethane foam installation foam.

If the rough wooden floor is to be insulated, the substrate is covered with a unique vapor-permeable membrane.

Use of special fasteners

Think about using self-tapping screws and flats with a diameter of five centimeters or more as special fasteners to securely fasten foam to a wooden wall.The length of the screws should be adequate to ensure that the insulation is fixed to the wall.

A unique pressure washer known as Rondol is designed with a unique cap that covers the self-tapping screw’s flat.

The following is the work technology:

  • First of all, it is necessary to prepare the base – if there are gaps or significant irregularities in it, they must be sealed to ensure the best effect.
  • The working process is carried out as follows: fastening is carried out from bottom to top, each sheet is fixed with several fasteners . The scheme below shows a variant of saving fasteners, it is not necessary to hammer all five rondoles on one sheet, you can fix the element in the middle, and use the rest in the corners, that is, they will hold several sheets at once, which several times reduces the consumption of materials.

When the clamping elements are positioned correctly, one rondolle can hold four sheets at once.

  • After the work is completed, it is necessary to carefully inspect the surface and if there are gaps, they should be filled with foam .


The only drawback of this incredibly dependable choice is the high cost of compositions, which is particularly apparent for large amounts of work.

The technology is straightforward but needs caution:

  • Before you glue the foam to the wood, it is necessary to level the surface, otherwise, if there are differences, the consumption of adhesive composition will increase many times, and the reliability of connections may decrease.
  • Next, you need to determine what to glue the foam to the wood, there are two main options: mounting polyurethane foam or a special adhesive composition, which is available in the same cylinders as the foam, but has improved properties and increased output. The second option is preferable, so try to use this one.

The adhesive and foam are applied with the same guns.

  • The surface should be cleaned of dust and do not have wet areas, as this negatively affects the adhesion of the composition. The composition itself is applied to the sheets in any way you like – serpentine, along the perimeter, dots. The most important thing – reliability, and other nuances do not matter.

Before fixing it, the composition is immediately applied to the foam sheet.

  • Then the element is tightly pressed for a few seconds, after which it can be released, the glue begins to set within half an hour, full hardening occurs in 24 hours.

Recall! The last step is to seal the gaps at the joints. This can be done with assembly foam or the same adhesive composition; it doesn’t really matter.

Preparatory measures

There are two methods for using foam plastic to insulate a house: using glue or specialized dowels.

You can save money on heating the space by using insulation. Foam can be fixed to the wall after the surface has been initially prepared.

The steps involved in the process are several actions taken to strengthen and level the base. Essentially, it comes down to this:

  • Unnecessary elements of the construction are removed from the working surface;
  • Falling off areas of the finishing coating are removed to a strong base, and then plastered again;
  • the walls are checked for irregularities with a level;
  • if necessary, the entire surface is leveled, putty;
  • after drying, the dust formed on the mounting plane should be washed off with water (can be wiped off with a damp cloth);
  • when the moisture evaporates, successively apply: a priming layer, a solution against mold and fungi (with a brush or sprayer);
  • before fixing polystyrene foam, it is necessary to take measurements of the wall (to order the consumable material in the right amount, convenient format).

The choice of tools is another preparatory operation. Depending on the method of fastening selected, the following set will be needed to complete the work:

  • spatulas of different sizes;
  • construction knife, stapler;
  • level, tape measure, pencil;
  • perforator (impact drill);
  • mixer or nozzle for stirring the adhesive solution;
  • sandpaper (grater);
  • hammer
  • containers for glue, primer, plaster mixes.

It is customary to give the initial preparation a lot of thought. Defect-free leveled walls expedite the process and prevent potential issues (such as plaster falling off the panels).

It is advised to use foam plastic that is at least 5 cm thick outside and 3 cm thick inside the rooms.

Penoplex what it is

The manufacturer started producing this type of insulation under the trademark Penoplex, which is also the common name for extruded polystyrene. Penoplex only recently made its way onto the Russian market. Penoplex can be used without the need for hydro- and vapor barriers because it is hydrophobic, has a low volumetric weight, and almost has no vapor permeability. Based on the index of thermal conductivity, it can be concluded that this is the best insulator currently in use. It is also the most easily processed and mounted on a variety of surfaces, including inclined, vertical, and horizontal.

One of the drawbacks is that Penoplex does not burn well; instead, it melts in the presence of fire and releases poisonous, acrid smoke. Furthermore, prolonged exposure to the sun causes it to lose its properties and become useless.

Advantages of insulation of walls from the outside

The owner of the house is always a question – to insulate the dwelling with foam with his own hands from the inside, or to install it from the outside? The variant of the location of insulation on the facade side is more preferable – it allows you to transfer the dew point in the insulation (subject to proper calculation of thickness) and thereby get protection of walls from excessive moistening. It should also be remembered that the internal location of foamlex significantly reduces the area of the house, and also leads to the need to produce wall decoration, which is not quite appropriate – well-treated wood looks good in the interior of the dwelling without any decoration. Therefore, it is better to insulate the wall surface with foam plex from the outside.

How to attach polystyrene foam to the wall

Utilizing dowels (also known as "mushrooms") and adhesive mixtures, thermal insulation is attached to the brick wall. The most dependable method for installing PPS slabs is combined, where a plate fastener is used to secure the slab in five points in addition to the surface glue.

The bottom corner of the wall is where insulation is started, but before you glue the first board in place, install a starter profile whose width matches the thickness of the foam plastic. A construction level is used to verify that the profile installation is correct.

You can apply the adhesive to the wall as well as the boards. Using a comb trowel, apply the glue. If the surface to be insulated is not level enough, the adhesive is applied. Here, the glue aids in blending inconsistencies.

Plan for using dowels to further secure foam plastic.

In order to ensure that there are no spaces between the panels, foam sheets are adhered to and pressed up against the brick wall. It is vital to use a construction level to verify that the board is installed correctly both vertically and horizontally before the glue solidifies.

You can begin adhering the subsequent row after laying the first one. Its vertical joints shouldn’t line up with the first row’s joints. Better wall insulation and dependable foam plastic fastening are guaranteed by using this technique.

After drilling holes through the thickness of the glued insulation, the dowels are screwed into the wall. It is advised to screw in the "fungi" to each board’s center and corners. The material should be slightly recessed to accommodate the fastener caps. The dowels can be screwed into the spaces between the panels to provide internal insulation. Fastener consumption is lowered by more than twice in this way.

Although foam can be used to fill potential gaps between insulation boards, it is preferable to use PPS dissolved in acetone or shredded foam. Glue is used to cover the sealed gaps.

Material features

Penoplex is an insulation made of extruded polystyrene foam that is created using a unique technology that results in a material with better strength characteristics. The article contains information on EPPS’s features and benefits.

Characteristics of the insulator

  • Water absorption. The material shows minimal values for the volume of absorbed liquid. At the same time, if water penetrates, then only in the upper layers, inside the structure, consisting of closed cells, access to the liquid is completely closed;
  • thermal conductivity. Penoplex indicators are very low – 0.03 W/m-K, and the values remain unchanged, regardless of the operating conditions. Therefore, the material can be used for thermal insulation of the roof, foundation, basement, as well as the floor and basement;
  • environmental friendliness. The insulating material meets environmental standards, which is confirmed by the relevant certificates;
  • vapor permeability. This indicator also has low values. The material does not allow vapor to pass through itself, which on the one hand can be called a positive property, as the insulation does not accumulate condensate, which at critical values goes to the wooden walls and causes rotting. But on the other hand, the material does not allow the wood to breathe, which contributes to the creation of a greenhouse effect in the room;
  • durability. The extrusion method results in a homogeneous material consisting of tiny cells. This structure provides high compressive strength;
  • chemical resistance. The insulator interacts well with a large number of substances used in construction: alcohol and water-based paints, acids, alkalis, oils, concrete mixtures, etc.д.;
  • service life. The material retains its properties for 50 years;
  • fire safety. Penoplex has a flammability class G4, which indicates a fairly high degree of combustibility. Therefore, when using the material, it is necessary to use fire retardant compositions;
  • Operating temperatures: from -50 to + 75 degrees Celsius.

It is not advised to use heated insulation—which can release harmful substances—to insulate the walls and floors of baths and saunas, where temperatures can rise as high as +95 degrees Celsius. Because heated air is always directed upward by the laws of physics, using it to insulate the steam room ceiling is extremely risky.

Types of Penoplex

The manufacturer creates a variety of foamlex varieties with varying densities and technical differences. The following varieties are designed to insulate homes composed of timber and logs:

  1. Thermal insulation boards for insulation of external and internal vertical structures: walls and partitions. The insulation has a milled surface, which improves adhesion to adhesive and plaster solutions. Density 22 kg/m3.
  2. Universal insulation material "Comfort" series. Suitable for flooring, including ground, basement, foundation, roofing, walls. The material well withstands high humidity, so it can be used for insulation of the bathroom, washing rooms of baths and saunas. Density from 22 kg/m3.
  3. Heat insulator for pitched roofs. The material has a U-shaped edge on all its sides, thanks to which the boards are conveniently and easily jointed. As a result, an even surface is created, which significantly reduces the thickness of the thermal insulation. Density 26-34 kg/m3;
  4. Foundation sheathing boards. The material is characterized by high strength and wear resistance and can withstand heavy loads. It is used for insulation of the foundation, floor, basement. Perfect for garden paths. Density 27-35 kg/m3.

Peculiarities of fixing insulation to the wall with dowels

The same technology is used to fix materials like polystyrene foam, foamlex, and Styrofoam. The insulation material is first prepared, and then an adhesive composition is used to attach the sheets to the walls. After the mortar has dried, fix the foam complex with dowels. However, treat every joint beforehand to prevent the formation of cold bridges. The insulating material is then completed with a finishing coat, which may consist of plaster or different panels.

The old plaster is scraped off the wall surfaces and any gradient defects are filled in with mortar before the insulation material is fixed. Subsequently, the surface is cleaned to promote high-quality adhesion between the adhesive composition and the wall.

Toluene, acetone, or any other organic solvents should not be included in the adhesive mixture used to fix the insulation material. Install a metal profile before laying the first row of thermal insulation to stop the sheets from moving downward due to gravity. Mushrooms are used to help with fixing after the mortar has dried. To achieve this, a drill bit with a diameter equal to the dowel rod’s circumference is used to create specific holes. Because the length of the recess is one centimeter longer than the dowel’s length, the fasteners will be fixed with reliability.

How to install dowels

Wall inscription

Proceed to install the dowels after that. Markings are made first. Drill holes through the insulation in the wall for the fasteners to be inserted using a perforator. Select a 10 mm drill bit and drill the hole to the necessary depth. It should be ten to fifteen millimeters longer than the dowel sleeve length of the relevant brand.

Controlling the tool’s horizontal position is crucial to preventing the dowel from becoming askew and projecting one side above the surface. Using insulating tape, a marker is made on the drill bit to guarantee that they are all equally deepened.

The hole’s diameter should allow the anchor to pass through it easily. If not, it may break and bend. Compressed air is used to clear the holes.

The foam is then directly fixed to the wall using dowels in the following step. Umbrellas made of plastic are put into the openings. To ensure that it does not protrude above the surface, the cap should be slightly recessed into the insulation. Because foam and mineral wool have low densities, they can be lightly tapped with a hammer or compressed by hand.

Next, the rod is pushed as far inside the umbrella as it will go. To level the hat with the foam, the remaining portion is hammered in with a hammer. When using plastic rods, be careful not to exert too much force. Nail deformation may result from this. In the event that fiberglass dowels are utilized, they are placed into the formed hole.

Fixing the dowels is the final step. By the time the work is finished, the flat caps are still present in fairly deep holes. The holes should be filled with glue mixture using a painter’s trowel to keep voids from developing there during later facing work. A level or an angle gauge are used to check the surface’s levelness. The surface is plastered or the curtain wall is installed following the dowel installation.

Installing fasteners at low temperatures is feasible because most contemporary fasteners are composed of impact- and frost-resistant polypropylene. They won’t break or crack.

For homeowners who want to increase their home’s energy efficiency, fixing foamed polystyrene insulation with dowel mushrooms is a useful and efficient solution. By securely attaching insulation panels, these uncomplicated yet sturdy fasteners contribute to the creation of a thermal barrier that lowers heat loss and lowers energy costs.

Dowel mushrooms’ ease of installation is one of their main benefits. Homeowners can quickly and effectively attach insulation panels to external walls, achieving a snug fit that maximizes the insulation’s effectiveness, with just a few simple tools and instructions. This do-it-yourself method can save costs and time when compared to more involved installation techniques.

Dowel mushrooms also provide outstanding weather resistance and durability, guaranteeing long-term performance even in challenging environmental circumstances. They offer a dependable solution that won’t deteriorate over time or jeopardize the integrity of the insulation layer because, in contrast to some alternative fasteners, they are made especially for use with foamed polystyrene insulation.

The adaptability of dowel mushrooms is another advantage. They come in a variety of shapes and sizes, are compatible with a range of wall substrates, including masonry, concrete, and brick, and can hold varying insulation densities. They can be used for a variety of tasks, from large-scale construction projects to modest home renovations, thanks to their versatility.

To sum up, dowel mushrooms provide an easy, affordable, and dependable way to repair foamed polystyrene insulation. Because of their adaptability, resilience to weather, durability, and ease of installation, they offer homeowners a practical way to raise comfort levels all year round and increase their home’s energy efficiency.

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Anna Vasilieva
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