Any private house has its own heating system on a particular energy source. Prudent homeowners are even considering multi-fuel systems or alternative heat sources. Since, however, various types of hydrocarbons (coal, gas, oil products) or wood are mainly used, their combustion products must be removed. And for this it is necessary to ensure the passage of the chimney through the roof. This task is not as simple as it might seem, but what are the ways to solve it - further in the article.
The main problems for the owners of private cottages are created by the requirements of SNiP 41-01-2003 "Heating, ventilation and air conditioning".Some of his requirements are clearly outdated, they mention materials and concepts that no one remembers these days.
However, supervisory services continue to be guided by this particular document - therefore, you have to follow its requirements.
There are several situations when it is necessary to draw a chimney through the roof:
- Construction of a new house
- Reconstruction of an existing roof with a heating unit installed
- Installation of an autonomous source of heat supply in an operated building
Of all the possible last option - the most problematic: when building a cottage and replacing the roof, all existing requirements can be taken into account even at the project stage.
Moreover, as a rule, the roof is repaired on those houses where one or another heating device has already been installed. Whereas when embedding, for example, a stove or a fireplace in an already built building, you will have to go through the roof "unscheduled".
ADVICE! Building owners who decide to install an automatically controlled boiler (for example, on gas or diesel fuel) can try to consider the option of adding a small room to the house for a boiler room, or leading a chimney through the wall, outside the building. In some cases, this turns out to be cheaper and more practical than breaking through on the roofespecially in high-rise buildings.
The reason for all the troubles lies in the roofing pie of the modern roof. As you know, it has a rather complex and ordered structure (starting from inside the building):
- Roof interior trim
- crate
- vapor barrier
- rafters
- insulation
- Waterproofing
- Control grille
- Waterproofing
- roofing material
Considering that most types of thermal insulation are made of synthetics, and hydro and vapor barriers are completely polymeric films, it is clear that they are all flammable materials.
With wooden rafters and battens, everything is also clear. Both the interior finish and the coating material can be combustible - that is, almost all layers of the roof. But the specified SNiP expressly prohibits the placement of flammable roof elements closer than 130 mm in light from brick, concrete, or ceramic pipes in thermal insulation.
For ceramic pipes without thermal insulation, this distance is almost twice as large as -250 mm. If we take into account that we mean the distance along the entire perimeter of the pipe, and add its own dimensions, we get a rather large hole in the roof that cannot be filled with “fuel”, including insulation.
It also expands the area of \u200b\u200b"damage" the need for a device on the pipe at the place where a special thickening passes - a retreat.
What are the consequences of this?
- There is a gap in the hydro- and vapor barrier - the insulation can be moistened, both from the top side and from the bottom
- The thermal insulation layer is torn - this can increase the heat loss of the building
- Air circulation in the under-roof space may be disturbed, and moisture will not be normally removed from the insulation
- The structure of laying the coating material is disturbed, the likelihood of rain falling into the resulting gaps increases, and in winter - the formation of snow pockets at the junction of the roof to the chimney
- The structure of the truss system may be broken, and with it the overall strength of the roof
Problem resolution
Is there a way to avoid these troubles? Rather, they can be reduced to a minimum. There are basically two solutions for this.
The first of these is to arrange your own truss system around the chimney. At the same time, rafter legs are arranged from the sides, and transverse beams of the same section as the rafters are arranged above and below.
The gap between the wooden structures and the pipe is filled with non-combustible material - some kind of mineral wool (basalt, for example).
Such materials are usually less sensitive to moisture than traditional semi-synthetic roof insulation, so the lack of waterproofing will not affect them as much.
This method creates for the chimney a kind of channel isolated from other roof structures. At the same time, around the rafter system created for the pipe, the layers of vapor and waterproofing are embroidered along the beams and the battens in the usual way - they are tucked up and fastened with staples or nails.
For reliability, it is worth sealing the joints with adhesive tape or sealing tapes. However, there is still a threat of violation of air circulation under the roof.
To avoid it, it is recommended to install ventilation parts, standard for this coating material, above and below the slope - aeration gratings, ventilation tiles or the like.
Important information! With a chimney width (over the outer dimension, perpendicular to the rafters) of 800 mm, a slope should be arranged above the slope - its own small roof that drains snow and water from the pipe.This is a rather laborious task, since the slope must be provided with all layers of insulation, and combined with the main roof using curly elements. Therefore, it is better to try to make a smaller pipe.
The second way to organize a passage through the roof for the chimney is to use special metal kits that many manufacturers now offer.
The part that is ultimately obtained is called cutting. It includes several components, each of which performs a specific purpose.
The principle of operation of this equipment is, in general, the same.
This device is called a modular chimney, and consists of the following parts made of stainless steel:
- The deflector is an aerodynamic device that, using the flow of rising hot air, increases the draft in the chimney
- Clamp for stretch marks - the pipe can be quite high, and require additional roof fixings
- Skirt - since the diameter of the pipe is obviously somewhat smaller than that of the steel apron through which it passes, the exit point is protected from precipitation by a skirt
- The roof passage is actually a metal sheet, directly laid on the roof, with a welded apron
This device is attractive because it is easier to fit into the overall appearance of a roof covered with modern roofing materials, creates a smaller opening in the roof, and is more technologically advanced in installation.
Important information! Not all homeowners are aware of some of the special requirements of SNiP regarding steel pipes for stoves (respectively, fireplaces).The use of metal is allowed only if the temperature of the outgoing gases does not exceed 500 °C. For stoves that are heated with coal, it is forbidden to use it at all. For asbestos-cement pipes, the temperature drops to 300 ° C, and the coal ban also applies. Also, the chimneys of houses where the furnace is fired with wood or peat must be protected by a spark arrester made of a metal mesh with a section of 5x5 mm
And in the case of a factory passage, and if the chimney is brick or concrete, it cannot be rigidly fixed to the roof structures. In the case of various deformations of the roof, exposure to weather conditions, a rigid fastening can transfer force to the chimney and destroy it. All connections to the roof are made on flexible elements.
Where will we place the chimney?
In SNiP there are instructions regarding the height of the pipe above the roof surface, and they are tied to the distance to the ridge. For houses with a flat roof, this distance is fixed -500 mm. For pitched roofs - there is some gradation.
This is 0.5 m when the chimney is located within 1.5 mot of the ridge, flush with the ridge - up to 3 m, and 10 ° from the horizon angle (a line drawn perpendicular to the top of the ridge) for large distances.
Important information! When calculating the height of the rooftop part of the chimney, many people forget about another requirement of SNiP, which states that if a building with stove heating is attached to another, higher structure, then the chimney must be brought out of the roof of the “neighbor”. If the house has a common wall with a high-rise building, even if it is 3 meters high, the pipe will still have to be pulled over the roof level of a high-rise building.
Regarding the practicality of the location of the pipe in a particular place on the roof, considerations may be different. However, if do-it-yourself house roof has a fairly large slope - at least 25-30 degrees, in winter, avalanches are possible along the slope, which can simply demolish the chimney. And this requires the installation of separate snow retainers. Also, the closer to the edge of the roof the pipe, the higher the likelihood of the formation of snow pockets.
Therefore, most experts still recommend extending the pipe as close to the ridge as possible - there will definitely not be pockets here, and it is much easier to arrange all the connections.
Often the ridge beam of the rafter system becomes an obstacle, but then either they retreat somewhat from the ridge, or they cut the beam and make special supports under it on both sides.
Be that as it may, people have been heating their homes with stoves for centuries, even when there were no SNiPs yet. The problem of combining the roof and the pipe has also always existed - but it has always been solved.
And in our time of high technology, there is sure to be a way to install a chimney on the roof and enjoy the warm and cozy atmosphere of your home. There are technical solutions - it remains to choose the right one.
Did the article help you?