Laying roofing around the chimney

A very crucial moment during the construction of a house is the correct laying of the roof covering around the chimney pipe. It is important to do everything so that the roof remains beautiful and at the same time airtight, to prevent leaks. Let’s talk about this, separately considering various materials for the roof.

First, let’s see where exactly the chimney on the roof can be located:

• The chimney should rise above the ridge itself by at least 50 centimeters, if the distance to it from the chimney does not exceed 150 centimeters.
• The distance to the ridge is no more than 300 centimeters – the height can be equal.
• The distance to the ridge is more than 300 centimeters – the height is at the level of the ridge or not lower than a line drawn at an angle of 10 degrees horizontally.

A chimney directly on the roof ridge is a popular solution. Installation is a little easier, because the ridge is a separate roofing element and it is easier to equip it around the chimney. In addition, snow will not accumulate behind the pipe wall. There is one minus, but significant – the ridge beam is either sawn and reinforced on the sides, or is absent. This can reduce the strength of the entire rafter system. However, many experts are still committed to this method of arranging a chimney, considering it to be quite reliable.

It is not recommended to install a chimney passing through the valley, the gutter. This is an already difficult place on the roof. The chimney here will cause snow accumulation, leaks and a violation of waterproofing are possible.

Experts believe that the best option is to place the chimney near the ridge. This will make it easier to organize the correct abutment, while there will be less risk of snow accumulation and depressurization..

The most important point when arranging a roof covering around a chimney is to provide protection against leaks. It is especially important to protect the thermal insulation, such materials lose their properties when exposed to moisture. In addition, according to the SNiP norms, it is necessary to remove the roofing cake located at a distance of at least 15, and preferably 25 centimeters from the chimney. This measure is intended to reduce the risk of fire..

The optimal solution to this problem is the construction of a protective box, an apron around the chimney. This is a one-stop solution for any roofing. Such a box is constructed using cross beams and rafter legs on the sides of the pipe.

Important! The gap between the chimney and the rafters is filled with exclusively non-combustible thermal insulation material! Mineral, stone, basalt wool would be a good choice..

It turns out that around the pipe there will be a separate rafter system and a separate layer of thermal insulation. We must not forget about waterproofing. For this purpose, modern elastic tapes are used, which already have an adhesive layer on one side. One edge of the tape is glued to the roof sheathing, the other to the base of the pipe. A metal strip is used to securely fix the edges. It must be attached with heat-resistant dowels to the pipe walls..

From above, the entire structure is closed with a steel apron, made of a sheet of steel cut and bent to the size of the pipe, which must necessarily go up to the chimney by 20 centimeters. If the pipe is next to the ridge, the edges of the metal apron can be tucked under it or even bend to the other side to increase reliability.

Important! All joints of the protective steel apron are coated with a sealant, which will eliminate the occurrence of leaks.

Important! In order not to make holes in the metal sheet around the chimney, it is fastened with clamps.

If the pipe is round, a universal glass, a master flush, is put on it, roof penetrations are used, which are connected to the cap, through which the chimney passes. Remember to carefully seal the joints!

The presence of a so-called tie, a steel sheet that fits from the roof eaves to the lower edge of the chimney is also an important detail in arranging a reliable coating.

These were the general rules for forming a roofing cake around a pipe. Now let’s talk about the use of various roofing materials:

• Metal tiles. In this case, the manufacturers themselves offer additional parts to create a coating around the pipe. In particular, metal strips and special pass-through units.
• Decking. The base is made according to the general rules, and a hole of the required size is cut in the roofing itself with a grinder. To lead the round pipe through the corrugated board, foil bitumen tape or bituminous waterproofing is used.
• Ondulin. This is flammable material! An interlayer between the pipe and the flame retardant coating is essential! Metal apron, roof non-combustible cutting is brought under the edges of the ondulin.
• Soft roof. It also burns, the gap to the chimney must be at least 15 centimeters. Instead of an elastic tape for waterproofing, in this case, an end carpet is used. You can also put roofing paper or shingles on the pipe..
• Slate. Previously, the chimney on a slate roof was often sealed with concrete on all sides. However, it tends to flake off over time, there will be a danger of leaks. Today, with the advent of modern sealants, many experts call this technology outdated. The technology of sealing is used with the use of adhesive waterproofing tape, pouring sealant and a steel apron.