Let’s talk about such a specialized type of fasteners as dowels for insulation. Let’s figure out what types of such an attachment exist, what are their pros and cons. We will tell you how to use the dowels correctly for the installation of heaters.
Due to its characteristic shape, a dowel for insulation is often called “fungus”, “plate” or “umbrella”. It is this mounting option that is most often used when installing various types of thermal insulation materials. Yes, you can put, for example, foam on glue-foam. You can simply put mineral wool in the prepared crate cells and close them with siding on top. However, in most cases, experts still use dowels for reliability. It can be confidently asserted that most of the processes of facade insulation involves the use of fungus dowels.
Why was it necessary to create a special mount for the installation of insulation? Because in most cases, insulation is a porous, loose, soft material. It cannot be nailed to the wall with just nails, the insulation should be handled with care in order to maintain its integrity, but at the same time it must be installed securely.
The dowel for insulation consists of the following elements:
- Hat. She herself is a “fungus”, “plate”, “umbrella”. This attachment part is designed to distribute the load over the surface of the material, not to allow it to concentrate in one place, which can damage the insulation;
- Expansion washer. It may not be there. The washer simply increases the area of the cap, serves as its complement. It is necessary when working with especially delicate, soft insulation. It is used when it is necessary to increase the contact area of fasteners with the surface of the insulation, to additionally distribute the load;
- Spacer element. Creates a frictional force, ensures that the insulation is fixed to the wall, bears the main load;
- Nail. It is hammered into the spacer to ensure a tight fit;
- Anchor sleeve. It may not be there either. It serves to strengthen the fastening and is not part of all dowels.
As you can see, by the number of elements, the dowels for insulation can already be divided into types: with and without expansion washers, with and without an anchor sleeve. The simplest dowel will include only a head, a nail and a spacer – this is the required minimum of this fastening.
In addition, there are dowels for insulating walls, including facades, and there are – for thermal insulation of the roof. The last version of the fastening differs in that it is a hollow plastic rod, an anchor or a nail passes through it, which is driven into a dense material – corrugated board or concrete. The photo clearly shows that the dowel for heat and waterproofing of the roof is seriously different from the front.
The rest of the dowels for insulation are divided into three types:
- With a plastic nail. That is, completely plastic, without metal parts. They are used most often because they are cheap and meet basic requirements. Dowels with plastic nails are able to withstand temperature drops from -40 ° C to + 80 ° C, designed for a load of 20 to 380 kg / m2. In most cases, these indicators are sufficient and homeowners decide to save money by buying dowels with plastic nails. But for heavy, thick insulation, a plastic nail is unreliable;
- With a galvanized steel nail, the rest of the dowel is made of impact-resistant polypropylene. Such dowels can withstand a load of up to 750 kg per “square”, they are more reliable than plastic ones. But they are also more expensive. In addition, metal conducts heat well and therefore can act as a bridge of cold, but we need to insulate the building;
- Dowel with thermal head. This is also a fastener with a metal nail, but a special polymer head is put on the end of the anchor. It is needed so that the dowel nail does not become a cold bridge, the thermal head reduces thermal conductivity. The most expensive type of dowel for insulation.
For comparison: an ordinary dowel with a plastic nail costs about 2–5 rubles apiece, with a metal nail – 4–10 rubles, and with a thermal head for a metal nail – 10–30 rubles.
The diameter of the head of the dowel for insulation ranges from 45 to 100 mm. If an expansion washer is used, then the contact area of the fastener with the insulation increases to 140 mm.
The diameter of the rod is usually 8 or 10 mm, but the length can be very different – on average, from 100 to 400 mm. It is easy to calculate the required length of the dowel: add 50 mm to the thickness of the insulation you are using (this is the minimum depth of entry of the rod into the base, that is, the wall), add the thickness of the finish, if it is on the wall under the insulation, and lay about 50 mm on the curvature of the wall.
Installing a dowel for insulation is simple:
- In the right place of the insulation, already laid on the wall, a hole is drilled, which should be 10 mm longer than the rod and correspond to its diameter;
- The dowel itself is inserted manually into the hole, so that its cap is flush with the insulation. If there is an expansion washer, it should be put on before inserting the dowel, under the head;
- A plastic or metal nail is inserted and hammered;
- If there is a thermal head – it is put on the nail.
A very important point is the calculation of the number of dowels per insulation plate. There are craftsmen who save and fix the insulation in the center for one dowel. This is clearly not enough!
According to experts, there should be 5-7 dowels for one standard-size insulation plate. One is attached in the center, the rest at the corners or at the joints.