How to insulate a chimney

Let’s talk about why you need to insulate the chimney, what benefits it will give homeowners. We will figure out what materials are advisable to use for insulating the chimney, how to make the right choice. We will offer technologies for insulating chimneys from various materials.

Why do you need a chimney? To remove smoke and other combustion products from the firebox of the boiler, stove, fireplace into the atmosphere. In this case, the chimney pipe undergoes considerable tests due to temperature changes and the effect of combustion products, exhaust gases. Moreover, the appearance of condensate in the chimney enhances the negative effect of weak solutions of sulfuric and nitric acids that are formed in it..

In an uninsulated chimney, the dew point shifts inward, that is, warm air begins to settle on the walls in the form of moisture. Imagine how negatively water droplets will affect a pipe, be it brick or stainless steel..

Chimney insulation solves three important tasks:

• Enhances cravings. Accordingly, the boiler or stove will perform better;
• Reduces the formation of soot and condensation, the chimney can be cleaned less often;
• Extends the life of the chimney.

Important! Experts assure that an insulated chimney will work 50% better than a conventional one. Therefore, think about this even at the stage of selection and construction of a gas outlet pipe..

So, it was decided – it is necessary to insulate the chimney. But the second question arises – how and how to do it? A good option is to buy a ready-made insulated sandwich chimney. Such a chimney consists of two steel pipes – external (casing) and internal. Thermal insulation material is placed between the pipes, most often mineral wool, for example, based on basalt. Double-walled sandwich chimneys do not need additional insulation. In addition, the insulation itself is inside, protected by an outer layer of stainless steel, so it does not need additional finishing and protection. This is a big plus of this option..

Chimneys-sandwiches experts strongly advise you to choose if almost the entire chimney goes outside, along the outer wall of the house.

The second option for insulating a steel or asbestos round chimney is special semi-cylinders or cylinders with a cut, shell. They are made of different diameters, you can always choose the size you need. Most often, cylinders for insulation are made of mineral, basalt wool.

Important! A shell for chimney insulation can be sold already with a protective layer of foil, fiberglass, sheet steel, fiberglass. Otherwise, the insulation will have to be independently protected from external influences in order to extend its service life..

The process of insulation with the help of a shell is simple – half-cylinders of a suitable size squeeze the pipe from both sides and are fixed with clamps, galvanized buckles, bandage tapes, for example, made of aluminum. Some homeowners use duct tape to secure the shell, but this is not a reliable option..

You can insulate the chimney located above the roof as follows:

• Use wooden shields. Build a skeleton of the desired size around the pipe. Slag, sand, asbestos are poured into the frame of wooden panels, felt or mineral wool is laid. Outside, the tree is sheathed with slate, metal tiles or other roofing material. In this case, the pipe will not only be protected from external influences, but will also become an integral part of the roof;
• Use an additional casing made of sheet steel, that is, sheathe the pipe with metal. There is a layer of insulation inside;
• Wooden shields can be replaced with reinforced concrete or slag concrete slabs. They are installed with a minimum gap around the chimney, seams, joints are reinforced with mesh for reliability. The remaining gap is filled with a solution of clay, sand, asbestos. From above the slabs are plastered;
• A metal or asbestos chimney can be bricked. The gap inside, again, is filled with insulation.

Important! If you decide to independently insulate an asbestos, brick or metal chimney, then experts strongly advise you to choose stone, basalt wool. This insulation is much more reliable than glass wool, it lasts longer, especially if it is protected from above, it is characterized by increased fire safety, more dense, vapor-permeable.

If we are talking about insulating a pipe in an unheated attic, then it will be enough to overlay it with basalt wool mats or wrap it with the same insulation, but already rolled. The material is attached to the pipe with metal strips and cords. Since there is no excessive moisture in the attic, the insulation is protected from rain by a roof, you can do without an upper protective layer.

Important! The stone wool should be laid as close to the chimney as possible! Otherwise, cold bridges may form in places of gaps..

Now let’s talk about choosing an insulation option, depending on the material of the chimney:

• Steel pipe. It is easier and safer to insulate such a chimney with a second steel pipe of a larger diameter. Stone wool will act as an interlayer between the pipes. The outer casing should be 10 centimeters larger in diameter;
• Asbestos chimney. It is most expedient to build a box on a frame, sheathe it with sheet steel, wooden shields, and fill the gap with insulation. The top of the structure must be covered with cement mortar;
• Brick pipe. It can be simply plastered using a mesh reinforcement to reinforce the adhesion and prevent cracking. However, experts call this method ineffective. It is safer to sheathe a brick chimney with stone wool, first by making a crate from a metal profile. On top of the insulation there is a vapor barrier film, and then either a layer of plaster, or siding, or roofing material.

Important! It is advisable to clean any chimney before insulation, replace worn out elements, for example, bricks that have begun to collapse.

We must also not forget about the chimney cap, which will protect the entire insulated structure..