Installation of roofing is in itself an extremely responsible task, requiring special care, consistency of action, and strict adherence to the developed technological recommendations. Whatever roofing material is used, it should ultimately provide one hundred percent protection of the building from the destructive effects of precipitation.
Connecting the roof to the chimney pipe
One of the most vulnerable components from the point of view of possible water penetration and difficult to install is the connection of the roof to the chimney or ventilation pipe. The durability of the rafter system, the attic floor, and often even the finishing in the house itself directly depends on how well such areas are sealed. Therefore, it is very important to treat this stage of roofing work with special attention and accuracy.
How far should the pipe be raised above the ridge of the bathhouse?
When installing a pipe, the following rule applies: “The closer to the ridge, the higher the pipe should be raised.”
Elevation of the chimney above the roof plane
- If the distance from the center of the chimney to the ridge of the roof does not exceed 1500 mm, the pipe must be raised above the ridge by at least 500 mm ;
- With a distance from the center of the pipe to the ridge from 1500 to 3000 mm, the top of the pipe can be at the same level as the roof ridge;
- At a distance of more than 3 meters, the top of the pipe must be no lower than a line drawn down from the ridge at an angle of 10 degrees to the horizontal.
Where is it better to route the pipe through the roof of the bathhouse?
The most convenient option for bringing the pipe through the roof is to pass it through the ridge. In this case, installation is easiest; there are rarely snow pockets on the ridge, and thanks to this arrangement, it is easy to carry out insulation work. But this method has a drawback: the rafter system should not have a ridge beam. An option with two beams that are attached in the area where the chimney passes through the roof is also suitable, but this is quite difficult to implement and is not always possible.
The most unfortunate option for placing a chimney is in a valley (a valley is a roof element made of a kind of tray, forming an internal angle between the joints of the pitched roof elements). Large masses of snow usually accumulate here; during rain, water flows down from two slopes, so even with the most careful insulation, a leak will only appear a matter of time.
The most convenient option for venting the pipe through the roof is near the ridge
Based on this, the most acceptable option for pitched roofs is not far from the ridge, but below it:
- installation is quite simple,
- There is usually little snow accumulation, which means there is no need to install snow retention,
- installation is not the most difficult,
- Due to the not very high height of the pipe, it does not need to be reinforced with braces.
If it turns out that the chimney runs close to the floor beams, or close to them (the minimum distance should be 13-25 cm depending on the type of pipe), exits in the valley or close to the slope, an additional elbow, with which you can lead the pipe to the right place.
If the roof of the bathhouse is pitched, the most reasonable solution would be to organize the pipe outlet through the roof near the top point of the roof.
Measurement methods
If you doubt that the chimney draft of a stove, fireplace or heating boiler is sufficient, you need to check it. The easiest way to dispel doubts is to check it yourself using an anemometer. If the device shows a draft of 10-20 Pa, then it is considered normal . The problem with this method is the low measurement accuracy of inexpensive anemometers; if the draft is less than 1 Pa, then they will show that there is no draft. More accurate professional instruments are expensive; they are used by stove makers.
If you don’t have an anemometer, use one of the popular methods for determining the draft force of a chimney:
- By the smoke. The most obvious sign that there is no draft is the presence of even slight smoke inside the room; a large amount of smoke indicates a high risk of fire and carbon monoxide poisoning.
Note! The draft inside the chimney duct is created due to the difference in pressure outside and inside the room. In a heated room, the temperature is higher than outside, so there is more pressure there. Heated air, supported from below by colder air, is squeezed into a zone with lower pressure, that is, into the atmosphere. If you take measurements in the summer, when the temperature difference between inside and outside is minimal, you will get a lower result than in winter.
How to remove a pipe through a roofing pie
Bathhouse roofs, as a rule, have solid insulation, which solves the problem of heat preservation. To ensure good heat and moisture protection properties of the roofing pie, it is necessary that the membranes and films of heat and moisture protection are continuous.
By bringing the pipe through the roof, we necessarily violate their integrity. Moreover, according to fire safety standards, the distance from the pipe to combustible materials (which are vapor barrier and waterproofing films) must be at least 13-25 cm . How to get out of this situation? The best option is to separate the area where the pipe passes through the roof. To do this, additional rafter legs are fixed at the required distance from the pipe on the right and left, and transverse beams are installed below and above at the same distance between these rafters. In this case, the pipe ends up in a separate box.
Roof passage unit
It often happens that “the pipe hits the rafters.” In this case, the rafter leg is cut, additional rafter legs are installed, as well as cross beams. This creates a box for the safe passage of the chimney through the roof
The space between the pipe and the rafter structure is filled with mineral wool. Not with fiberglass - it does not tolerate high temperatures, but with basalt wool, which tolerates temperatures normally and does not lose its heat-insulating properties when exposed to moisture.
At the same time, to ensure the tightness of the roofing pie within the box in which the pipe will be located, the materials are cut into an “envelope”, the edges are wrapped up to the beams and rafters, secured with staples or nails (counter sheathing strips can be used). To prevent moisture from entering, the areas where materials adhere to the wood must be additionally insulated using adhesive tapes or sealants.
The roofing pie at the passage site is cut into an “envelope” and secured to the sheathing and rafters
But there is another option. If the temperature of the pipe in the area where it passes through the roof does not exceed 50-60°C, you can simply glue the roofing cake films using the same sealants and adhesive tapes. This is possible if, for example, a tank for heating water is installed on the pipe after exiting the firebox or an additional heater is installed, etc., but it is not a sandwich that goes out onto the roof.
In any case, to drain condensate in the waterproofing layer, you will need to attach a drainage groove. You can buy it (usually it is made from stainless steel), or you can make it yourself from a film of sufficient thickness. The groove is secured around the pipe and its end is pulled out to the side. Thus, the condensate flows into this groove and is discharged onto the roof slope.
Causes of malfunctions
After making sure that there is not a sufficient level of draft inside the chimney system, you need to determine and eliminate the possible cause of this defect. Experienced craftsmen claim that the most common causes of failures in smoke exhaust ducts are:
- Design error. The choice of chimney pipe should be made based on the volume of the firebox. If the diameter is less than the calculated parameter, the weak one will not allow smoke to escape from the room.
- Insufficient pipe length. A pipe length of less than 5 m does not provide a significant difference between the pressure indoors and outdoors, which results in weak draft.
- Incorrect placement of the chimney pipe. I advise stove technicians to lay the chimney vertically, as narrow turns trap smoke inside the chimney, reducing draft.
- Long horizontal sections. If, when laying a chimney, you cannot avoid horizontal sections, then make sure that their length is no more than 100 cm. Otherwise, it will need an amplifier.
The first step when detecting problems in the chimney system is to dismiss the most obvious causes of insufficient draft. When inspecting, make sure that the connections of all pipe segments are tight and that there are no soot blockages. Check that no moisture has entered the smoke exhaust ducts and that the atmospheric pressure is normal.
Passage through the roof depending on the roofing material and type of chimney
When passing through the roof, the most important thing is to remove the water flowing down the roof and the pipe itself. To protect against precipitation, protective aprons are used, the upper edge of which is placed either under the sheet of roofing material located above, or under the ridge.
The apron is placed either under the sheet of roofing material located above or under the ridge
When venting the chimney through the roof, it must be fixed, but so that it remains movable relative to the roof. Otherwise, due to thermal expansion/contraction, the integrity will be compromised and leaks will certainly appear. For example, a round pipe can be given direction by metal strips or corners.
When installing, check the verticality using a plumb line - this is important so that soot does not accumulate and there is good traction.
The pipe should not be fixed rigidly when passing through the roof.
Brick pipe passage through the roof
If the chimney is brick, rectangular or square in shape, you can use the materials included with the roofing material.
When passing a brick pipe through the roof, you can use elements offered by roofing material manufacturers
If the roof is made of metal tiles, then the companies that produce it offer special tapes for sealing the joint with the pipe, on one side of which an adhesive layer is applied. These elastic bands are a complex compound containing aluminum and/or lead. One edge of such a tape is glued with the adhesive side to the base of the chimney, the other - to the roof sheathing. The upper edge is additionally fixed with a metal strip, which is attached to the brick with heat-resistant dowels.
To reduce the likelihood of water flowing along the wall, you can make a recess under the bar - a groove. Then the tape and bar will be in the recess. To completely eliminate water seepage, a heat-resistant sealant is applied to the joint.
They practically also seal the passage of a pipe through a roof made of soft tiles or roofing felt. But in this case, instead of an elastic tape, the tiles or roofing felt themselves are placed on the chimney.
When a pipe passes through a roof covered with soft tiles, its edges are placed on the chimney or apron
You can make an apron for a square or rectangular pipe yourself. Roofers usually use sheet metal for this, but sheet aluminum works well. Four separate parts are made of metal - two side, front and back.
An apron for a rectangular or square pipe is easy to make yourself
The metal strips are bent so that one part fits onto the pipe, and the second is attached to the sheathing. In a brick chimney, in the upper part of the apron, an edge is made, which is inserted into a special groove and coated with sealant. To prevent water flowing down the apron from getting onto the sheathing and insulation pie, a sheet of metal of large width is placed under the front part of the apron, with curved sides along the edges. It goes under the roofing material and is called a “tie.”
If metal tiles are used on the roof, then an apron is made from a smooth sheet of the same color, the upper edge of which is tucked under the row of roofing material located above so that water flows onto the apron and does not flow under it. If the pipe comes out close to the ridge, you can either tuck it under the ridge itself, or bend it to the other side.
There is one important nuance: if the width of the brick chimney is more than 80 cm (its size is perpendicular to the rafters), you need to make a slope - a small gable roof located higher. It removes sediment, reducing the likelihood of leakage. But such a width of chimneys in a bathhouse is the exception rather than the rule.
Passage of a round pipe through the roof
Modern round chimneys in bathhouses are usually a sandwich pipe. Occasionally, you can still see asbestos pipes on the roofs of bathhouses, and even more rarely - a single pipe without thermal insulation.
A simple single wall, which is discharged through the roof, carries a very high probability of a fire. Therefore, using this option is extremely undesirable.
Modern round pipes are usually sandwich pipes
The video below shows an option for sealing a pipe when installed on a metal tile roof.
If metal tiles are used as a roofing material, then manufacturers often offer roofing passages. They are made from a sheet of the same color and connected to a special cap through which the pipe passes.
Pipe passage through a metal roof
It is easy and simple to seal a round pipe on the roof if you use a factory penetration. It consists of an aluminum flange to which an elastic part made of rubber or silicone is attached.
Factory-made penetrations are the easiest option for sealing the junction of the pipe and the roof
They come in different sizes and have different slope angles. You can choose it for any diameter, roof type and installation location. The penetration flange is coated with a composition similar to the composition of the corrugated part; there are grooves along the edges into which they are filled with sealant. One of the penetrations, “Master Flash,” has 11 sizes that cover diameters from 3 to 660 millimeters.
Walkthrough "Master Flash" MASTER FLASH
When installing such a penetration, part of the corrugation is cut off in accordance with the required diameter. Then it is put on the pipe. The rubber must move with force to ensure a tight fit. Since the hole is about 20% smaller than the diameter of the pipe, you have to pull hard. To make less effort, you can lubricate both with soapy water.
How to install a factory penetration
After the corrugation is pulled to the desired location, the flange is given the required shape - the material is plastic and you can use a hammer, but you need to work carefully.
Using a hammer, give the flange the required shape
Then the grooves located on the inside are filled with sealant, the edges are pressed against the roofing material and secured (self-tapping screws are included in the kit). If the roofing material is not iron, self-tapping screws are not suitable. You need to use either long screws that will reach the sheathing, or dowels for the floor slabs.
Split model of penetration
There are quite a few options for factory-made penetrations, and there are detachable models. They are used when there are thickenings on the pipe or when they have to be mounted on an already assembled chimney of great height. In this version, the kit includes clamps that connect the parts of the passage to each other. The rest of the installation is similar.
The video shows how to seal a penetration through a regular slate roof using a MASTER FLASH corner penetration.
What is a sandwich chimney?
In another way, designs of this type are also called modular chimneys.
Such pipes can be used when installing boilers and stoves for heating residential buildings and baths. Chimneys of this type are assembled by inserting individual parts into each other using the “condensate” or “smoke” methods. Sandwich pipe elements can be made from stainless or galvanized steel. The first type of structure is used most often by owners of country houses. Galvanized chimneys, since zinc can burn out at high temperatures, are mainly used only when installing gas boilers or boilers.
Pipes of this type received their original name for their multi-layer nature. When assembling such structures at the factory, another one is put on the main smoke exhaust pipe, which acts as a protective casing. Mineral wool is also installed between the pipes inserted into each other.
The main advantage of sandwich chimneys, in comparison with conventional single-wall structures, is that condensation does not form inside them during operation. Acid never accumulates in such chimneys and soot is not deposited. Accordingly, the service life of exhaust gas exhaust structures of this type is quite long.
Roof sealants
In order to seal the joints of different parts of the bathhouse pipe passage through the roof, you need to use not just a roofing sealant, but always a heat-resistant sealant. It is advisable to use a neutral silicone heat-resistant sealant.
If Master Flash is installed on a metal roof (metal tiles or metal profiles), then it is necessary to use silicone sealant that does not contain vinegar (non-acetic sealant). This is necessary so that it does not enter into a chemical reaction with the metal and does not destroy it.
Roofing silicone sealant retains its properties in the range from -50°C to +300°C, which is sufficient for all weather conditions and is quite suitable for sealing a chimney.
Roof sealant must be neutral and heat-resistant
But you need to remember that the surface to be treated must be clean and dry. The time for complete hardening is indicated on the packaging, usually 24 hours.
Fire safety precautions when using MASTER FLASH
MASTER FLASH made of silicone can withstand temperatures up to +300 degrees Celsius. This is quite enough to seal a sandwich pipe and, in many cases, a chimney made of asbestos-cement pipe.
The passage through the metal tile is sealed using a Master Flash penetration. Additionally used bitumen tape
As for the metal mono-pipe, in these cases it is possible to use MASTER FLASH in cases where the length of the chimney from the stove to the passage through the roof is at least 3 meters. As a rule, in this situation the temperatures will not be critical, but if not, then thermal insulation of the area that passes through the roofing pie is necessary.
Elastic penetration
Most often in private construction they are faced with the installation of round metal pipes. To ensure the tightness of the passage, a special device is used - an elastic penetration. This is a product made of high-strength silicone or rubber, shaped like a funnel with a wide flange in the form of a square or circle, called an apron. Thanks to its properties, the elastic penetration takes any shape, adapting to the angle of inclination of the slope. It can withstand extremely high or low temperatures, exposure to aggressive chemicals and comes in a wide range.
Installation diagram of elastic penetration
Elastic penetration on metal tiles
When purchasing an elastic penetration, they are guided by the diameter of the pipe and the color of the roofing material. Universal models, in the form of a stepped pyramid, are suitable for any size; adjustment is carried out by trimming the penetration to the desired level. Installing an elastic apron on the roof is very simple, you need to place it on the chimney passage, apply a metal circle with holes for fasteners, treat the joint with fire-resistant sealant and secure it with a screwdriver. For roofs with steep slopes, a special type of plastic penetrations with a specified flange mounting angle is used.
