Brick chimneys are often installed in stoves, fireplaces and boilers in private homes for the removal of fuel combustion products. Designs of this type are distinguished by their durability, but at the same time they are considered quite difficult to install. When designing and assembling a chimney made of brick, certain rules must be observed.
Pros and cons
The main advantages of brick chimneys, in comparison with metal, in addition to durability, are:
Brick chimneys in the vast majority of cases simply fit perfectly into the interiors of almost any design. Such designs look very harmonious in rooms decorated in a classic style, loft, country, Provence, chalet and even modern.
Unlike metal chimneys, brick after heating can for a long time give off heat to the surrounding air, thereby increasing the efficiency of the furnace equipment.
Such structures are erected from a material that is not susceptible to rust and fire resistant. Brick chimneys never burn out and can serve faithfully for up to 50-100 years.
The pipes of this variety, therefore, have many advantages. But such chimneys, of course, still have some drawbacks. In addition to the complexity of installation and relatively high cost, the disadvantages of structures of this type include:
Brick chimneys in private homes have to be cleaned from time to time during operation. Unlike metal, the walls of such structures inside have a rough surface. This explains their ability to retain soot.
Since brick chimneys have significant weight, they have to be equipped on the most solid bases, which, of course, significantly increases the cost of installation work.
Types of chimneys
Pipes of this type can be built in private houses:
The first type of chimneys is equipped directly on the stove (and sometimes on a solid fuel boiler). It is these pipes that are laid out in private homes most often. In order for the stove to support the weight of the chimney of this variety, its walls must have a thickness of at least two bricks.
Main pipes are placed at a short distance from the heating equipment on the foundation. Chimneys of this variety are usually equipped for boilers or stoves of a modern design.
Sometimes in private homes can be used and wall pipes for exhaust gas. Such structures are mounted inside the walls separating the heated rooms. Sometimes chimneys of this type are also equipped in the external enclosing structures of private houses.
Configuration
Brick chimneys are erected according to schemes of a special variety - ordinances. The design of this type of pipe is relatively uncomplicated. For fireplaces, for example, it can even be simply direct smoke channels laid out using the “brick” technique.
The structural elements of the outlet pipes of modern furnaces and boilers are usually:
the neck of the fenders with a smoke gate that opens to the ceiling;
fluff - a thickening in the ceiling, reducing the risk of fire;
riser - the longest part passing through the attic to the roof slope;
otter - an extended part that prevents the ingress of snow, debris and rain into the chimney and reduces the risk of fire of wooden elements of the rafter system;
neck and head;
metal cap.
The foundations for the main chimneys of furnaces and boilers are poured the most reliable and durable - stove.
Design: calculation of the cross-sectional area
Brick chimneys, for obvious reasons, are usually square or rectangular in shape. The best option for home heating equipment is, of course, a pipe with a circular cross section. However, to lay out a chimney made of brick in this way, of course, is not possible.
When designing such pipes, it is important, among other things, to determine their cross-sectional area. This indicator primarily depends, of course, on the capacity of the furnace equipment itself, which is determined depending on the size of the heated room and the degree of its insulation.
In any case, the cross section of the chimney for a brick furnace or solid fuel boiler, according to the standards, should not be less than 130x130 mm. Such pipes are usually built for furnaces with heat transfer up to 3500 watts. If the house uses more powerful heating equipment, it is supposed to build a chimney for it with a cross-section of at least 260x260 mm.
A rough calculation of the required pipe dimensions can be made depending on the volume of the combustion chamber. It is believed that these indicators should correlate with each other as 1:10. Also, when designing a chimney, the fact that its cross section should not be less than the area of the blowing hole should be taken into account.
Total pipe height
When designing the chimney, this parameter should also be calculated as carefully as possible. If the pipe is too high, excessive traction will subsequently be created. And this, in turn, will lead to a significant reduction in the efficiency of heating equipment and an increase in fuel consumption.
Do not make the chimney for a brick stove or boiler in the house too low. This, in turn, can lead to unnecessary turbulence in the shaft and the formation of reverse thrust. Operating a furnace or boiler with such a pipe can even be dangerous in the future. Lack of traction leads to smoke in the premises when laying firewood or coal in the furnace. That is, people living in the house in this case can simply be poisoned by carbon monoxide.
According to the norms of SNiP, the “correct” brick chimney, including in a low-rise building, must have a height of at least 5 m. At the same time, the length of the pipe should start from the level of the grate in the combustion chamber and end with the trim of the head (excluding the hood).
The height of the pipe on the slope of the roof
Metal chimneys of furnaces and boilers can be displayed on the street, including through the walls of the house. Brick structures of this type in the vast majority of cases are laid during installation, of course, through the overlap and slope of the roof. When using this technology, among other things, the following standards should be adhered to:
if the distance between the pipe and the ridge does not exceed 1.5 m, it should rise above the last one by at least 50 cm;
with a distance between the pipe and the ridge from 1.5 to 3 m, a brick chimney on the roof can be erected at the level of the latter.
If the pipe is located further than 3 m from the ridge, assemble it so that its upper edge is on a conditional line drawn through the vanishing point of the slopes at an angle of 10 degrees to the horizon. Over flat roofs, brick chimney masonry is made to a height of at least 50 cm.
The choice of masonry material
Sometimes chimneys in private homes are erected from fireclay bricks. However, such material, unfortunately, is very expensive. Therefore, more often such pipes are still assembled from ordinary full-body burnt red brick. Such a stone is able to withstand fairly high temperatures, is relatively inexpensive and lasts a very long time. Brick chimneys are mounted from this type of material in a bathhouse, in small private houses, cottages.
It is believed that only fired stone of the first grade should be chosen for exhaust pipes. In this case, the pipe, during operation, exposed to various kinds of adverse environmental factors, as well as strong temperature extremes, will subsequently last as long as possible. By strength, for assembling the chimney of a private house, you should choose a brick of a brand not lower than M150 / 200.
In some cases, owners of suburban residential buildings have to construct pipes from second-grade material for some reason, exhaust pipes. In principle, standards allow this. However, such a pipe at the final stage must be additionally plastered (part of the structure above the ramp). Before performing the actual masonry itself, such a brick should be soaked in water. In this case, he will not subsequently draw water from the fastening mixture and, accordingly, the masonry will be more durable.
What solutions can be used
Masonry mixtures for the installation of brick chimney pipes also need to be selected with the utmost care. Such structures are mounted usually using three types of solutions:
Mixtures of the first variety are used where the pipe is very hot during operation. Using such a solution, the lowest part of the chimney is usually laid on the last rows covering the furnace. Also, fluff is often collected on such a mixture.
For laying the riser, otter, and all other parts of the pipe, clay-cement mortar is usually used. In these places, the chimney can also heat up, but not too much.
Pure cement mortar is usually used if the pipe is not built on the furnace itself, but on a separate foundation. In such designs, the lower rows are always subjected to severe loads due to the large weight of the brick. The cement mixture in such chimneys, called, as we have found, indigenous, is used for laying the first two rows. The remaining parts of the pipe are assembled according to the same rules as when erected directly on the furnace.
Preparation of mixtures
The clay for the solution, when kneaded, is first broken and soaked. Sand is mandatory sifted to remove debris, stones, organic inclusions. These two ingredients are mixed in proportions, depending on the fat content in the particular area of clay.
Sometimes masonry is performed on such a solution prepared industrially. Clay mixture of this kind can be purchased today in almost any construction supermarket. The only thing - in this case you need to buy material intended specifically for laying stoves. Such mixtures, among other things, are able to withstand significant temperatures.
Cement mortar in most cases is prepared in proportion with sand as 1/3 or ¼. For plasticity, a little slaked lime is most often added to such a mixture.
Cement-clay mortar for installing a brick chimney is usually prepared according to this recipe:
Chimney foundation
Conventional exhaust products of combustion of the pipe are laid out as a continuation of the furnace, in accordance with the orders. Indigenous chimneys, as already mentioned, are collected on a solid foundation. They fill the foundation for such pipes using standard technology.
First, a pit is dug for the construction of a concrete slab. If the chimney is laid out inside the house, the depth of the latter is usually 50 cm. If the pipe is built on the street, the foundation pit is dug below the level of freezing of the soil.
Further, in any case, the foundation is poured using the following technology;
the bottom of the pit is sprinkled with a mixture of crushed stone and sand;
formwork is installed in the pit;
a reinforcing cage is installed;
concrete pouring is performed.
Installation of a brick chimney, according to the standards, should be carried out on a foundation with a basement height of at least 30 cm. At the same time, the finished base plate should extend at least 15 cm from all sides outside the planes of the pipe riser.
How to make a brick chimney: masonry rules
When assembling the pipe itself, certain recommendations should be followed. Masonry should be done first of all so that there are no protrusions and depressions inside the shaft. The seams during the construction of the pipe should be flush with the wall. If the home foreman does not have the chimney assembly experience, he should use special steel or wooden templates when laying. Such elements are simply inserted into the pipe and lifted higher and higher by the handles as it is erected.
At the end of the brick chimney masonry, plastering work is usually carried out only from the outside. Inside, the surface of such pipes is in most cases left to be left unfinished. In the plastered mine in the chimney, subsequently, various kinds of chemical reactions will begin to occur, contributing to the destruction of the masonry. In addition, such a finish in the future will most likely collapse and clog the pipe.
Sometimes in large houses, brick chimneys with several channels are erected at once. The thickness of the partitions in such structures, according to the standards, should be at least 12 cm. That is, they need to be built using the half-brick method.
Very often, the chimney barrel in a private house passes through an unheated attic. In this case, it is supposed to build it according to the technique into a brick. That is, the wall thickness of such a chimney should be at least 25 cm. If the pipe is built in a cold attic according to the half-brick method, it should be insulated with mineral wool at least 5 cm at the final stage.
Assembly rules in buildings of foam blocks
Sometimes brick chimneys in houses have to be erected next to walls assembled from such material. Foam and aerated concrete blocks at the moment are very popular among the owners of suburban areas and are used for building houses quite often.
With such walls, the chimney is usually connected using 6 mm wire or strips of steel 1.5x20 mm. Lay these elements most often in every second row of the pipe or in each row of the building envelope. In this case, wire or plates are inserted into the masonry to a depth of at least 20 cm.
Installation in a wooden house
In such buildings, exhaust pipes should be laid with utmost care. The wood ignites already at a temperature of 300 ° C. Inside the chimney, the air temperature can reach 500 ° C. Sometimes in such pipes an open flame is even observed.
In wooden houses, therefore, chimneys should be insulated not only in places of laying through floors and slopes, but also next to the walls. According to the regulations, such pipes are supposed to be located at a distance of not less than 25 cm from the log cabins when using two layers of asbestos gaskets and 38 cm in the absence of the latter.
How to pass through the overlap and the slope: standards
Fire safety standards when laying chimneys in private houses built of any materials should, of course, be observed without fail. Through the ceilings and slopes of the roof, such pipes should be carried out correctly. If the brick chimney comes into contact with the wooden elements of the ceiling of the house and the roof, this can lead to fire of the latter and a fire.
When passing through the ceiling, it is important first of all to correctly calculate the thickness of the joint. This parameter is determined taking into account the cross section of the pipe itself. According to the regulations, the joint is assembled so that its height is at least 70 mm greater than the overlap thickness. Very often, the “step” of the transition between the chimney itself and the cutting of the master equip in the attic. This allows you to make a flat ceiling in the house. However, some experts still do not advise doing so. The fact is that fire departments often require that the chimney lining protrude both below and above the ceiling. Altering the pipe in the future if necessary, of course, will be extremely costly and time-consuming.
It is impossible to fix rigidly the bricks of a brick chimney to the materials of the ceiling. It is also not recommended to lean it on any building structures. Between cutting and overlapping structures leave free space, which is subsequently filled with non-combustible materials. Most often, mineral wool is used to insulate pipes in our time.
The distance from the walls of the chimney otter to the roof slope structures, according to the standards, should be at least 13 cm. This space should also be covered with non-combustible material.
Direct penetration
In small private houses, brick chimneys for boilers or stoves through the ceilings can be carried out without bridging. In this case, the work of laying the pipe through the ceiling is usually performed as follows:
3-4 rows to the ceiling level, a fiber cement sheet with a hole cut in the center is put on the constructed chimney;
the pipe is laid to the height of the clean floor of the attic;
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Roof sealing
When laying a chimney through a slope, a hole of the corresponding area is cut out in the roofing material. Subsequently, moisture can penetrate into the space between the walls of the pipe and such sheets, of course. To avoid this, such a gap, of course, needs to be repaired.
To seal the space between the brick pipe and the edge of the roofing material in the classic version, a steel apron is used. In this case, the work is carried out as follows:
the pipe will be ditched at a small height from the plane of the ramp;
along the perimeter of the pipe, a wall internal profile is laid on the waterproofing;
the upper part of the planks is turned into a strob;
treat the joint with sealant;
the lower part of the strips is made under the roofing material;
fasten a drainage tie with gutters under the sheets of roofing material;
cover the entire structure from above with a decorative steel apron.
At the final stage, the apron is attached to the sheets on the slope with roofing screws. After this element is fixed on the roof, proceed to install the cap on the brick pipe of the chimney.
Warming
This procedure is usually carried out to reduce heat loss of the pipes. Most often, such insulation of the chimneys of private houses is done by plastering. The pipes are insulated in this case as follows:
reinforced mesh is fixed on the surface of the chimney;
prepare a liquid plaster mixture;
cover the chimney with plaster in 3-5 layers.
At the end of the work, the walls of the chimney, insulated in a similar way, should be covered with a layer of plaster of 4 cm. This insulation method allows to reduce heat loss of pipes by 25%. At the final stage, the made plaster layer is sanded with a paint grater in order to give the chimney an aesthetic appearance.
In a cold attic, as well as above the roof, chimneys can be insulated, including using basalt wool slabs. In this case, the heater itself is first attached to the pipe walls. Next, the chimney is sheathed with asbestos cement sheets and plastered.
Arrangement of the outlet channel inside the enclosing structures
Intra-wall chimneys are very often used for solid fuel and gas boilers in large-area houses. In this case, in the building envelope, they simply leave an unburied mine. Its cross-section is calculated in accordance with the fact that per 1 kW of the boiler should be 0.08 m 2 . For example, for a heating unit with a capacity of 10 kW, it will be necessary to leave a shaft with a section of 0.8 m 2 (about 300x300 mm) inside the wall.
The boilers are connected to the chimneys in the brick walls by means of pieces of ordinary steel pipes. The same elements are often inserted inside the shaft. Insulate pipes in such chimneys, usually using mineral wool. Sometimes basaltine is also used for this purpose. An insulator pipe is wrapped before installation in the mine.
Pipes for heating units operating on blue fuel
Of course, special requirements are imposed on gas brick chimneys when installed in private houses. Designs of this type should be as safe as possible in operation. After all, the accumulation of gas in the premises can lead to tragic consequences. Among other things, the outlet pipe of the heating equipment operating on blue fuel should have a design that makes it easy to inspect and clean it.
The required cross-sectional area of a metal or brick chimney for a gas boiler is separately specified in the instructions for the latter. But in any case, such a pipe should have a cross section of at least 5.2 cm 2 per 1 kW of power. In this case, the aspect ratio of the brick pipe of such an aggregate or shaft inside the wall should not be more than 1 to 2.
Connection of several heating devices
Sometimes the owners of country houses connect to the chimneys simultaneously a stove, a boiler, and, for example, a fireplace. Doing so is permitted, but not in all cases. You can connect any additional heating equipment only to brick chimneys for solid fuel boilers. If there is a gas heating unit in the house, an exclusively separate chimney is supposed to be assembled for it.
A bit about metal pipes
In most cases, stoves and fireplaces in country houses are equipped with brick chimneys. For boilers, gas or solid fuel, metal structures of this type are most often used. It can be either simple steel pipes or modern, durable and easy-to-use sandwich structures.
Metal chimneys of both of these types can be led outside through the roof or through walls. In the first case, the pipe is passed through the overlap and the ramp in special passage nodes, which are an insulated mineral wool duct.
Metal chimneys are most often passed through a brick wall as follows:
a hole of the corresponding diameter is drilled in the wall;
on the external facade of the house, elements are installed to support the chimney in a given position;
collect part of the chimney from the boiler to the hole;
collect an external chimney with a wall mount on the clamps.
After installing such a pipe, it is mandatory to check for operability.