How to properly lead the chimney through the roof

Furnace and boiler units installed in residential buildings, baths, garages and other premises are equipped with a channel for the removal of waste generated during fuel combustion. Bypassing SNiP norms when arranging a chimney or using unsuitable materials can be fraught with the destruction of a building. To prevent this from happening, the passage of the chimney through the roof must be equipped correctly.

The need for a device for a passage through the roof

The passage through the roof for the chimney may be needed when constructing a building, installing a boiler or stove in it, or when overhauling the roof. When building a house from scratch, there are usually no difficulties with the correct arrangement of the chimney, since the work is organized in accordance with the project and the instructions attached to it. If a tenant decides to install heating equipment in an already operated building, the question arises of organizing the passage of the chimney through the roof in compliance with fire safety standards and high-quality insulation of damaged sections of the roofing from moisture.

If the design of the unit allows, the chimney unit can be made outside the building. This is especially advisable when using fuel oil or diesel fuel, as it will help rid the inhabitants of the dwelling from the specific smell of these substances.

Consequences of poor-quality installation

When organizing a roof penetration for a chimney, it is important to provide good protection against moisture. Therefore, you need to follow the installation technology and use high-quality materials. Insufficient pipe insulation contributes to an increase in fire hazard. In addition, it causes the following negative consequences:

• brickwork collapses due to a weakened solution, smoke penetrates into the dwelling;
• moisture accumulates inside the chimney, and a fungus appears in the summer;
• heat losses are growing, which makes it necessary to spend more fuel for heating;
• the sections of the roof adjacent to the pipe are destroyed by ice.

If the circulation of air masses in the space under the roof is disturbed, humidity rises, and wooden parts begin to rot. There is a need for overhaul of the rafters. Therefore, it is important to carry out the work on the arrangement of the sinking correctly.

Fire safety

The rafter system, as well as the steam and waterproofing layers of the roof, can melt or ignite when heated. To close the components vulnerable to the action of fire, a protective box made of a block of wood treated with anti-flammable and anti-rotting compounds is mounted around the perimeter of the hole. It is installed from the outside on the same level with the crate. Insulation layers must be fixed around the perimeter. The canvas is cut with a cross and triangles are wrapped inward. The material is fixed with staples or large nails. For sealing, the joint can be treated with a special compound.

The passage of the pipe through the roof presupposes the isolation of the chimney from temperature effects: for this, the corresponding sections must be sheathed with a non-combustible gasket, for example, from basalt wool. For the organization of penetration, it is forbidden to use parts that do not have heat resistance.

Choosing a place for a chimney on the roof

When organizing the passage for the chimney, it is important to choose the correct location for the outlet duct on the roof. The pipe should be close to the highest point of the roof. In this case, a number of fire safety requirements must be observed:

• the dimensions of the section and the height are selected based on the advice of the manufacturer of the heating equipment used;
• it is necessary to remember about the direct correlation between the height of the chimney duct and the resulting thrust force of the unit;
• the channel should end 0.5-1.5 m above the roof ridge;
• in order not to damage the rafter system, the exit is placed between its components;
• if the pipe is low on a slope, you need to make it long in order to fit into the recommendations for elevation above the roof elements;
• the structure is made up mainly of vertical parts of the tubes (the length of the horizontal ones is no more than 1 m).

Nodes of passage should not be placed next to the windows of the attic, otherwise the products of fuel combustion will be blown into it by the wind. At the places where the slopes form the inner corner, this is also not worth doing. It is difficult to realize a good connection to the pipe there. In addition, snow accumulations appear in these areas in winter. It is impossible to rigidly fasten the chimney structure to the roof: if the latter is damaged, the pipe may collapse. It also increases the likelihood of fire.

What determines the choice of the design of the passage assembly

The final design of the passage is determined by several factors. The final solution is influenced by the operating characteristics of the heating unit and the roof itself.

Flue pipe material

Most often, these structures are made of refractory bricks, stainless steel and other metals. Ceramic and asbestos-cement chimneys are less common. The materials used make certain requirements for the choice of the shape of the node.

Fuel combustion temperature

Different types of fuel burn at different temperatures. This affects the selected raw material. For example, if you use solid fuel (wood, peat briquettes, compressed coal), you cannot install a metal pipe.

Chimney exterior finish

Brick lining or plastering is usually practiced. The method of finishing influences the design of the unit, since the chimney lined with decorative bricks is heavier.

Roofing type

It is more profitable to build a configuration with a section that has the shape of a rectangle or square. For such options, ready-made additional components are produced, which are used when arranging the connection with the roof.

Options for the passage of the chimney through the roof

To lead the chimney through the roof, you need to make a hole in it. For a brick pipe, its diameter should exceed the diameter of the chimney by 0.25 m. If the roof is made of non-combustible material (for example, asbestos-cement slate), the indicator can be reduced by 3-5 cm.

If the roof is tiled, it will be necessary to install an additional structural element of rafters and lathing when making a penetration. Wooden parts should be treated with a fire-prevention impregnation and insulated with a fire-resistant material - for example, soft mineral wool is suitable. A protective apron is placed under the tube next to the ridge beam. If it is removed from the ridge, the apron is inserted from one side onto the chimney structure, and from the other it is hidden under the roof.

Correct implementation of the passage of the chimney through the roof minimizes the likelihood of fire. When calculating the dimensions of the structure, it is necessary to comply with the norms of SNiP.