Technology of laying a chimney made of bricks

Few things are more crucial to maintaining a warm and comfortable home than a well-designed chimney. A well-built chimney is essential to ensuring safe ventilation and effective heating, whether you’re huddled by the fire in the winter or relying on your stove for warmth on chilly evenings. We’ll examine the technology underlying brick chimney installation in this guide, along with the necessary steps and important things to remember.

As a dependable and long-lasting solution for releasing smoke and gases from residential buildings, brick chimneys have withstood the test of time. They not only offer superior heat retention, but they also give any house a hint of classic charm. Brick chimneys, when built properly, offer long-lasting performance and require little maintenance, in contrast to metal chimneys, which may deteriorate over time due to exposure to extreme temperatures and weather conditions.

Prior to beginning the process of installing a brick chimney, it’s critical to comprehend the different parts that comprise this vital structure. The components of a standard brick chimney are the base, the throat, the smoke chamber, the flue, and the foundation. Every part is essential to maintaining adequate ventilation, keeping smoke out of the living area, and helping to release combustion byproducts.

Setting up the foundation is one of the first steps in constructing a brick chimney. To sustain the weight of the chimney and guarantee its stability over time, a strong foundation is necessary. To stop shifting and settling, the foundation may need to extend below the frost line, depending on the particular requirements of your building and local building codes.

Building the chimney’s base comes next after the foundation is in place. In order to achieve the required height, this usually entails placing a course of bricks on top of the foundation and building upward. To guarantee structural integrity and adequate ventilation, great attention to detail must be given to the brick alignment and spacing.

What are the types of brick chimneys?

Brick stove chimneys come in a variety of designs, depending on the location of installation, the stove’s architecture, and the number of heating appliances that will be connected to the pipe. Hence, distinguish between the nozzle, root, and wall pipe types of brick chimneys.

• Chimney extensions. The most widely used constructions are extension chimneys. They are good because they are compact and do not take up any additional space in the room, but are simply a vertical extension of the stove.

In essence, an extension chimney is the stove’s upward extension. Frequently, the plan for setting up the first section of pipe is included in the staging of the stove.

They are built around the hole left by covering the stove with the top row of bricks. Subsequently, the pipe ascends above the roof after passing through the attic floor, attic, and rafter system.

• Root chimneys. This type of chimney is installed in cases where it is planned to connect a metal stove, or several heating devices located on one or even several floors.

Metal stoves can be connected to root chimneys. as well as a number of heating units spread throughout the building’s levels.

In addition to metal stoves, brick stoves can also be connected to such a pipe. Especially convenient this type of chimney, in the event that the house needs to build two stoves in neighboring rooms. For example, the kitchen needs a stove with a cooking stove, but the next room only needs a heating stove. In order not to build a separate pipe for each of them, a root chimney is built between the rooms, to which both heaters are connected. To this type of pipe can be connected not only two, but also three – four stoves, located on different floors of the house. In any case, it is necessary to calculate the size of the internal channel of the chimney very accurately, otherwise it may not provide a normal draught at the simultaneous operation of several appliances. The answer to the question of why there is no draught in the stove reasons can be different.

• Wall chimneysThey can be built near capital (external or internal) walls or built into them. They can be used, in the same way as the root, to connect several stoves located on different floors of the building.

Wall chimney, set into the exterior of the home’s outer wall.

This construction is convenient because it appears to be outside of the living area rather than taking up space. For instance, the house’s first floor can be constructed and linked to the wall-chimney fireplace (where the pipe will follow a construction principle more akin to a nozzle), and the second floor can have a metal stove chimney cut into it (much like in the variant with the root trebe).

The significant project cost and labor-intensive work are the drawbacks of this chimney design. First off, a lot more construction materials will be needed to erect this structure. Second, if the chimney is partially exposed to the street, it needs to be properly insulated. If not, condensation will form in the internal channels during the winter months due to temperature fluctuations, which will drastically lower the heater’s efficiency. It would therefore be wiser to sacrifice the space inside the building and lead the pipe along the inside wall of the house if this chimney option is selected.

In this article, we"ll delve into the ins and outs of laying a brick chimney for your home. Building a chimney isn"t just about stacking bricks; it"s a precise process that requires attention to detail and proper technique. From laying the foundation to constructing the flue, every step plays a crucial role in ensuring the chimney"s safety and efficiency. We"ll explore the technology behind laying bricks for a chimney, including the materials needed, the importance of proper measurements, and the techniques for achieving a sturdy and well-functioning structure. Whether you"re a seasoned DIYer or considering hiring a professional, understanding the fundamentals of brick chimney construction will help you make informed decisions and create a cozy, warm atmosphere in your home while ensuring safety and compliance with building codes.

Parameters of brick chimneys

Main sections of a brick chimney stack

Brick Chimney is separated into departments, each with a distinct name and a purpose assigned by the council. In order to make the description of the work on the pipe’s construction easier to understand in the future, these features should be specified right away.

Diagrammatic representation of the sections of a typical brick chimney

1. The chimney’s head. When laying this section of the chimney, the bricks are moved outside to create a sort of "visor" that appears to overhang the lower portions, partially shielding the pipe’s walls from precipitation.

2. The pipe neck has no protrusions, extensions, or narrowings and is situated directly beneath the casing. Its perimeter is the same the whole height.

3. Because "Otter" is meant to serve as a protective structure, its masonry scheme is more intricate. First, the masonry "otter" that overlaps the opening created by the roofing material and pipe walls seals it against precipitation infiltration and makes room for the installation of waterproofing material. Second, its enlarged walls become a safety guarantee because they provide the required degree of thermal insulation where the roof covering would have otherwise allowed passage.

4-An apron, or other sheet made of metal, is installed in the bottom portion of the otter to create a molding-like structure that seals the seam between the roofing material and the pipe’s brick wall.

The pipe’s "Raspushka" section, which is located where it passes through the attic floor, is the fifth section. Raspishka and Otter’s walls are thicker than those of other flat sections of the chimney because you can’t let them overheat due to the flammable materials that frequently make up the attic floor. This is done for fire safety.

6-Building the roofing material.

7- The riser, a straight section of the chimney from the "flue" to the "otter," is situated in the attic space and has uniform masonry throughout its height.

8. The ceiling in the attic.

9-A fixed umbrella cap, which keeps water and debris out of the inner chimney channel, is frequently installed on top of the header.

You may be interested in learning more about the features of a roof chimney.

The main function of the chimney is to efficiently discharge combustion products from the firebox into the atmosphere. For this purpose, the chimney is connected to the numerous channels in the stove structure, with which it must harmoniously cooperate. If the stove and chimney are built correctly, in accordance with the designed parameters, then when operating the heater inside the channels should create a good draft, which will contribute to the timely removal of smoke to the street. However, at the same time, this should not lead to the fact that the heat generated by the stove will literally fly out of the stove into the pipe. In short, you need a "golden mean" in everything.

A brick chimney’s internal channel irregularities are a direct route to the soot that accumulates there quickly.

Cross-section of the chimney channel

The capacity of the stove and the size of the furnace chamber must be considered when selecting the proper chimney channel cross-sectional dimensions. Longer-lasting cleaner chimney ducts are those with smooth inner walls free of protrusions and mortar buildup.

This is why extra mortar that sticks out of the joints during bricklaying needs to be cleaned off from both the inside and the outside of the walls. Some homeowners who have stoves or fireplaces in their homes employ an alternative technique to achieve a smooth surface on the channel walls: installing inlay, or ceramic pipe, inside the brick chimney.

This design has several benefits, not the least of which is the tab’s perfectly smooth inner walls. Because of its round cross-section, which eliminates corners, the smoke streams will not encounter any obstructions on their path, resulting in no needless swirls or "reverse draught" effects.

Diagrammatic representation showing how gaseous combustion products move through the chimney channel

The "ideal" hot gas flow in a round cross-section chimney is depicted on the right. It spirals into a regular shape and encounters no obstructions.

This spiral in a square-cross-section pipe is encircled by "parasitic" vortices, which invariably form at the corners (see figure on the left). The normal flow of gases is already slowed down and somewhat disturbed by this, and the signs of a steady, smooth draught are declining. Of course, the situation is much worse in rectangular cross-section chimney channels.

In addition, it should be taken into account that chimneys with a large width, which are still installed in older houses, often have a poor draught. This is due to the fact that the air heated in the furnace in a large space inside the pipe, quickly cools down, which leads to the formation of condensate, which contributes to a decrease in draught, as well as smoke in the premises, rapid soot overgrowth of the channel. To heat a stove with this chimney design, too much fuel would have to be used. Therefore, it will be most rational to correct them by dismantling the wide upper part of the chimney, then narrowing the shaft and installing in it a round or square with rounded corners, ceramic, metal or asbestos insertion.

A large brick pipe with the necessary cross section narrowed by ceramic and metal inserts

From form to linear parameters now. One of the most crucial elements is the size of the chimney channel’s internal cross-section, since it directly affects the heater’s efficiency. Maintaining the proper proportion between the heater output and the cross-sectional area of the chimney is mandatory. The blower door opening can also be used as a guide when determining the proper channel size; in any case, the pipe’s cross-section shouldn’t be smaller than the blower opening.

The chimney shaft’s cross-section can be calculated as follows in relation to the firebox window’s size. The average chimney opening size for fireplaces with an open firebox is 1:10. Nevertheless, this figure may differ in one way or another based on the cross-sectional shape and pipe height. The table below provides an estimate of the channel’s cross-sectional area (in percent).

Ratio f/F in percentage (where F is the firebox window’s area and f is the chimney channel’s cross-sectional area)

Chimney height, m	Shape of the cross-section of the inner channel of the chimney pipe
CROWN	QUADRATE	RECTANGULAR
5	11.2	12.4	13.2
6	10.5	11.6	12.3
7	10	11	11.7
8	9.5	10.5	11.2
9	9.1	10.1	10.6
10	8.7	9.7	10.2
11	8.9	9.4	9.8

It is obvious that starting from a reasonable height for the chimney is also important, in addition to the size of the furnace window; for example, a massive 10-meter chimney on the roof of a small, squat country house would look completely absurd.

The computation is not hard in and of itself. The table shows how the ideal f/F ratio is calculated based on the height of the chimney and the design of its inner channel. The area of the chimney channel can then be easily calculated using the furnace window’s area as a guide. The obtained value must then be converted to linear dimensions, such as the diameter for a round pipe or the length of the sides for a rectangle, using geometric formulas.

The calculator below uses this calculation algorithm:

Calculator for calculating the linear parameters of the chimney channel cross-section

It should be noted that the suggested cross-sectional area for a square or circle is expressed in millimeters, either as side length or diameter. Variations are possible for rectangular cross-sections; that is, one side may be lengthened at the expense of the other, but only if the cross-sectional area is roughly equal to (not less than) the recommended value "̒" (measured in square centimeters).

Determining the cross-section of a brick chimney channel can also be done by calculating the stove’s heat output. Though it is "tied" to the size of masonry bricks, it is more straightforward.

Depending on the stove’s heat output, this table will assist in selecting the cross-sectional size (without accounting for joint thickness, which can range from 6 to 10 mm):

Heat output from the furnace at two firing times per day, kW (kcal per hour)	Minimum channel cross-section
– in millimeters	– in brick parts
up to 3.5 (3000)	130×130	½×½
3,5÷5,2 (3000÷4500)	130×190	½×¾
5,2÷7,0 (4500÷6000)	130×260	½×1
over 7.0 (6000)	190×260	¾×1

Following the above calculations is required to guarantee that the heat transfer matches the heat output specified in the project.

The brick kiln is laid in accordance with the cross-section that is calculated using this method. The masonry options are displayed in the table below, which accounts for overlapping masonry joints, or alternating even and odd rows:

The size of the cross-section of the chimney channel		Laying scheme of alternating rows of bricks
– in millimeters	– in brick parts
130×130	½ × ½
130×190	½ × ¾
130×260	½ × 1
190×190	¾ × ¾
190×260	¾ × 1
260×260	1 × 1
– standard whole row bricks, 250×120 mm
– ¾ brick, 185×120 mm

Height of the chimney pipe

In brief, the height of the chimney pipe was one of the parameters used to determine the channel’s cross-section. It was already mentioned above. We must now examine this more closely. What height is ideal?

• Firstly, the longer the heated air stays inside the chimney and the stove itself, the more heat will be transferred to the premises. Therefore, if the height of the pipe is chosen correctly, it will normalize the draught and contribute to the maximum preservation of heat inside the stove for a longer period of time.
• Secondly, if the chimney is too high, it will lead to an increased draught, so the heat, as they call it, will "fly up the chimney", and the furnace will not have time to fully warm up. In this case, a much larger amount of fuel will be needed to heat the house well.
• Thirdly, an insufficiently high chimney can contribute to unnecessary swirls in the chimney shaft and, as a result, the formation of a back draft, which will lead to smoke in the house with the risk of carbon monoxide poisoning.

It is necessary for the chimney’s height to be at least five meters. In this instance, the height count does not account for the cap, vane, spark arrestor, or any other device that is placed on top of the pipe; rather, it begins at the furnace chamber’s grate level and ends at the head’s trim.

Depending on the location of the chimney section in relation to the ridge, any existing roof extensions, and the pitch of the rafter system, the height of the chimney section rising above the roof is always an important parameter. An unacceptable reduction in draught may also result from an incorrect calculation of this section’s height. Furthermore, it is imperative to safeguard the roof covering from any potential sparks that may not have burned all the way through.

When constructing a brick chimney, particular guidelines that are based on particular calculations should be adhered to. Take note of the diagram:

Diagram showing the appropriate chimney height ratio based on roof location

• If the chimney exits through the roof covering at a distance L1, not exceeding 1500 mm from the ridge (when measured horizontally), its upper end trim must be raised above the ridge by at least 500 mm.
• The chimney pipe passing through the roof at a distance of 1500 to 3000 mm from the ridge (L2 on the diagram) should be at least at the level of the ridge.
• Chimney, installed from the ridge more than 3000 mm (L3), should be its upper edge on the conditional line drawn through the point of the ridge at an angle of 10 degrees to the horizontal.

The pipe’s height above the roof covering in any of the aforementioned scenarios must not be less than 500 mm, regardless of the distance to the ridge. This holds true for all flat roofs as well.

Last but not least, a crucial note on chimney parameters. Although self-calculations are a great tool, hiring a professional designer is always the best option because of the significant impact a well-designed and folded chimney can have on both safety and heating efficiency. Being inexperienced in such important matters is a very dangerous endeavor.

It should be noted that the majority of developer-published layouts for brick stoves and fireplaces finish with a cross section that has already been calculated and tested. It shouldn’t be widened or narrowed; a calculated, well-proven chimney flue will ensure the stove operates safely and most effectively.

I’m sure you’d be curious to know how wood stoves are constructed.

Materials for masonry brick chimney stack

How to choose the best brick for chimney construction?

It is crucial to purchase high-quality bricks for masonry chimneys because these sections of stove construction are exposed to a wide range of harsh environmental conditions, such as wind, precipitation, humidity, and UV radiation. High furnace temperatures and the volatile chemical makeup of fuel combustion products are also factors that must be considered.

Because the roof chimney is exposed to harsh weather conditions, only premium bricks should be used for it.

Thus, premium full-body fired bricks should be used to build chimney pipes. This particularly applies to open spaces above roofs.

It is important to understand that there are three grades of fired red ceramic brick, and that the intensity of the firing process determines which grade the brick belongs to.

Selecting first-grade brick is essential to ensure the pipe is constructed with the highest level of durability.

• First grade Red ceramic bricks are characterized by high quality and moderate firing. It has the following characteristic features:

– high clay density, meaning that there are essentially no pores in the final brick;

– When a hammer is used to tap brick, it rattles;

It is distinguished by smooth surfaces free of cracks, depressions, and other flaws, as well as even ribs devoid of crumbling and potholes;

– highest resistance to frost;

In essence, the material is bright orange or red in color.

• Second grade- it is an under-burnt brick, which is characterized as follows:

– There’s a brief, muffled sound when you tap on it;

– the brick has poor density and frost resistance; – it is porous, making it unsuitable for building chimneys;

– surfaces might be scratched and ribs might be partially collapsed, which would complicate the masonry process;

Pale orange or unsaturated pale ochre in color.

• Third grade – overburnt building material, which has the following characteristic features:

The sound produced by striking the brick with a hammer is quite loud;

The material structure is dense and porous at the same time.

– the brick has a high heat conductivity and a low resistance to frost, which is not at all advantageous for a chimney in an open area;

Because overburned brick is brittle, it cannot support heavy loads without cracking or splitting;

– Ribs may sustain damage and surfaces may chip;

– The range of color tones is deep red to dark brown.

For the chimney stack, only the first grade of brick with strength grade M150÷200 is suitable.

If you must construct a chimney using second-grade unfired brick for any reason, the exterior walls of the chimney—which are situated above the roof deck—must be properly plastered; otherwise, the brick will quickly deteriorate due to moisture and cold temperatures.

Plastering a brick chimney is a common method to strengthen its resistance to weathering from the outside.

Every kiln maker uses a different method when laying bricks. Before beginning work, some artisans would rather soak the brick, while others would rather let it dry. The purpose of the soaking process is to prevent the brick—especially second-grade brick—from absorbing moisture from the masonry mortar and to allow the joints to naturally dry gradually. When masonry is done this way, it is typically far stronger than when dry bricks are used.

The brick surfaces and their recognized names are depicted in this illustration.

The terminology used to identify brick surfaces is another thing that novice bricklayers need to understand about this building material in order to communicate "the same language." They will be helpful in comprehending the masonry process description.

Which of the mortars used for masonry chimney?

Stove art has its own secrets when it comes to choosing and utilizing different materials for their work. In this regard, masonry mortar is not an exception.

A properly chosen masonry mortar is extremely important.

The masonry components of the stove and chimney, which will be exposed to the elements and an open fire, require special consideration when selecting the mortar composition since they are the heaviest loads of all the loads. As a result, after the mortar mixture dries, it must produce tight, sturdy joints that can endure the effects of numerous, intrinsically diverse factors.

A stove structure with a chimney stack is divided into various zones, each of which can use up to three different types of masonry mortar, as seen in the illustration below.

Additionally, different furnace sections call for a different method when selecting masonry mortar.

It makes sense to go into great detail about the masonry work that went into building the chimney and how it connected to the channel that removed the combustion products from the furnace chamber within the confines of this publication. As a result, we will now discuss zones 7, 8, 9, 10, and 11. If a root chimney—which is laid from the foundation—is selected, section No. 3 must also be addressed in addition to these areas.

• Division No. 7- is the beginning of the masonry chimney around the hole left on the last, all-over stove row. This zone is called the source, and it experiences quite high temperature loads of 360÷400 degrees, so for masonry in this area used clay-sand mortar.
• Department No. 8is called "fluffing" and may consist of 2÷4 rows. Sometimes it is only indoors, such as in the illustration provided. Then it serves to install a metal box filled with insulating material (here it is shown under area #9). In other variations, the "fluffing" starts in the room and runs through the entire thickness of the attic floor, all the way to the clean attic floor. This area of the chimney has thicker walls, and is designed to reliably insulate combustible elements of the ceiling and attic floor from the heat, reaching also up to 360÷400 degrees, which is formed inside the chimney channel during the furnace furnace heating. Bricks here are laid also on clay-sand mortar.
• Department No. 9 -the thermal insulation section in the form of a box. The partition is made of metal sheet, and is fixed around the pipe in the area of its passage through the attic floor. The metal box is filled with non-combustible material. It can be expanded clay, asbestos, vermiculite, mineral wool and other non-combustible materials with low heat transfer coefficient.
• Section No. 10 – this part is called the neck of the pipe. One part of it is located in the attic, most often unheated, and the second part is elevated above the roof covering. This area is exposed to various external influences, so for masonry in this area it is necessary to use a reliable mortar that can withstand any tests. Such a masonry mixture consists of sand and clay, but already with the addition of a certain proportion of cement. The same mortar is used for the "otter", if it is provided in the construction of the pipe.
• Section No. 11 – The chimney header uses the same mortar as for area #10.
• Section #3will be necessary when installing the indigenous version of the chimney, as it is installed on the foundation, next to the stove. This area is subjected to high mechanical loads, as it will be pressurized by the masonry of the entire pipe structure. For these two rows of masonry use a mortar made of cement and sand, in proportions of 1:3 or 1:4. Some craftsmen for plasticity and to extend the setting time of the mortar add ½ part of lime to it.

If you can obtain sand and high-quality clay, you can make mortars on your own for the furnace’s construction, such as clay mortar for masonry stove proportions. Sand makes everything clear, but for stove work in particular, purified clay can be bought at a building supply store.

Packing of refined clay to make mortar for masonry stoves

The cost of kiln clay

kiln clay

Furthermore, modern building material producers provide a ready-made dry mix for kiln work that is made up of refined ingredients in the predetermined, balanced ratios. This is an option if you want to complete masonry work quickly, but the cost of such mortar will obviously be a little higher.

Using premade masonry stove mortar, which is available as a dry mortar mix, is a very practical choice.

If obtaining the materials for mortar production is to be done independently, keep in mind that this will require a lot of labor. The ingredients must first be thoroughly cleaned to remove any contaminants and extraneous plant matter. Furthermore, the clay needs to be able to be chosen based on its appropriate fat content.

The cost of heat-resistant mortar mixtures for masonry fireplaces

heat resistant masonry kiln mortars

The following table lists a number of "recipes" for mortar used in kilns.

mortar no	Mortar ingredients (parts of total volume)
clay	cement M400	lime	gypsum	sand	asbestos fibers NO. 6-7	fireclay clay
1	1	–	–	–	2	0.1	–
2	1	–	1	–	2	0.1	–
3	–	–	2	1	1	0.2	–
4	1	1	–	2	0.1	–
5	1	–	–	–	4	–	1

It must be made correctly for the mortar to be easy to work with, particularly if you have to compose it yourself. Furthermore, kneading the dough to complete homogeneity is crucial.

For masonry stove structures, mortar calls for a unique method of masonry. The importance of properly mixed masonry mortar cannot be overstated. The reader will find a plethora of useful information on this subject by clicking the link. opens a unique version of our portal that is dedicated to discussing mortars designed especially for furnace masonry.

Step 1: Prepare the foundation	Step 2: Build the base of the chimney
Step 3: Lay the first course of bricks	Step 4: Install the chimney liner

It takes skill and tradition to install a brick chimney in addition to practicality. Although brick chimney construction technology has changed over the centuries, it is still essential for dependable home insulation and heating. Every stage, from the meticulous brick placement to the material selection, is essential to guaranteeing the chimney’s longevity and effectiveness.

The foundation is one of the most important parts of installing a brick chimney. A strong foundation keeps things stable and stops settling, which eventually can cause structural problems. To sustain the weight of the chimney and withstand the weather, the base and footing must be prepared properly. Paying close attention to detail during this phase is essential for a successful installation, regardless of whether it’s a new construction or retrofit.

In and of itself, bricklaying is a science and an art. Expert masons place every brick with precision, guaranteeing uniformity in pattern and tight joints. Since mortar holds bricks together while allowing for thermal expansion and contraction, selection is crucial. A well-done bricklaying job adds to the chimney’s overall strength and longevity in addition to improving its aesthetic appeal.

In addition, adding the right insulation to the chimney improves its performance and lowers heat loss. The inner walls are frequently lined with insulating materials to reduce heat transfer to the surrounding structure, such as vermiculite or perlite. This insulation not only makes the chimney function better, but it also lowers the risk of creosote buildup and stops condensation, improving safety.

In summary, the process of installing a brick chimney blends old-world craftsmanship and cutting-edge technology to produce an essential part of home insulation and heating. Every stage, from the foundation to the final details, needs to be carefully planned and carried out to guarantee a sturdy and effective chimney. Homeowners can invest in a heating system that not only keeps their homes warm but also endures over time by knowing the fundamentals of insulation and bricklaying.

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