Reliable fastening of the insulation is a mandatory step in creating thermal insulation for a room. Soft, loose and porous sheets or mats, which are easy to fix, are chosen as the insulating material. For small volumes, they are fixed on glue or simply placed between the bars. In the case of large-scale construction work, it is necessary to use special fasteners - dowels. They differ in the method of fastening, material of manufacture, length and diameter. Before starting work, it is necessary to choose the right holders for thermal insulation.
Types of retainers
Insulation is a heterogeneous multilayer material, often with a porous structure. The complexity of its fastening lies in the risk of violating the integrity of the structure, especially when using waterproofing and vapor barrier. For this reason, retainers are divided into two main groups:
- dowels for facade work and wall insulation;
- dowels for roof insulation.
The first type of fasteners is an integral or collapsible structure in the form of a mushroom. The collapsible one consists of a sleeve with a spacer part, a head in the form of a pressure disk and a rod. The dowel for insulation differs from the usual only in the increased volume of the head. The disc diameter is 45-90 mm. Made from various types of plastic and metal.
The second type of dowels is a hollow plastic rod with a wide clamping disc. It has a special way of installation - into the body of the heat insulator. The nail goes through and sinks into concrete or other dense material.
Criterias of choice
The quality of fastening the material to the surface depends on the correct choice. When choosing dowels, you need to pay attention to several factors:
- Length. It depends on the thickness of the insulator and other layers, the deviation of the wall from the vertical, the minimum allowable deepening.
- Pull-out load.
The shape also depends on the material. Lightweight heat insulator does not withstand rigid attachment.
Varieties of dowels
Dowels can be classified according to several criteria - by design, material and design. The choice depends on the characteristics of the insulation itself.
Design
There are two main methods of fastening:
- Spreadless. The dowel does not need hardware. The fasteners are installed in a pre-drilled hole through the insulation.
- Spacer. A nail or screw is driven into or twisted into the body of the rod. A hole is pre-made under the rod, into which it must be placed.
The first option is used for aerated concrete, and the second for dense materials (brick, concrete).
Manufacturing material
The dowel itself is made from different types of plastics. It is forbidden to use metal due to its high thermal conductivity. A screw or nail is made of plastic or metal.
The main types of plastics for dowels:
- Nylon or polyamide. It is a lightweight material with a high degree of strength. It can be used to mount to any surface. The maximum permissible load on the fasteners for the insulation is 120 kg. Working - 30 kg.
- Polypropylene. Differs in increased strength and hardness. The load reaches 150 kg.
- Glass fiber reinforced polyamide.It is a new material that has the same strength as metals. It has low thermal conductivity, which makes it a material of higher priority than metal parts.
The spacer rod can be made of the same plastic as the mushroom dowel for thermal insulation, or from metal.
The following materials are used from metals:
- Cink Steel. The thickness of the zinc layer must be at least 6 µm. It is used under normal conditions with normal humidity levels.
- Stainless steel. This is a more expensive fixative, but it does not corrode. The main area of use for steel holders is in places with high levels of humidity.
By design, there are:
- The nail and the dowel are made of the same type of plastic. It is not advised to use different types, since their coefficients of thermal expansion will differ. The thermal insulation dowel with a plastic nail is used in almost all climatic conditions.
- The dowel is made of plastic, the rod is made of metal. The fastening is improved, but the metal conducts heat. This leads to the formation of a cold bridge.
- Plastic dowel fungus for insulation and a metal rod with a thermal head. This design avoids the appearance of a cold bridge. The screw head is covered with a nylon cap and the nail is inside.
Each of the combinations of dowel-nails for thermal insulation has its positive and negative sides, as well as its own cost. The choice depends on the climatic characteristics of the room in which the insulation is carried out.
Product dimensions
There are no GOST standards for plastic dowels, but they exist for polyamide products. The document specifies what brand of plastic can be used and in what macroclimatic conditions.
The insulation fasteners must be of sufficient length. This is due to the deepening through several layers of thermal insulation. The sizes of other parts vary within a small range:
- head diameter - from 45 mm to 90 mm;
- 2 rod diameters - 8 mm and 10 mm each;
- length from 40 mm to 400 mm.
The bearing capacity depends on the strength of the retainer and the material of the walls. The load can be from 0.3 kN to 23 kN.
The length can be calculated using the formula L = H + I + K + W. L - dowel length, H - insulation thickness, TO - the thickness of the layer of plaster or glue (if any), I - additive for fixation in concrete / brick / wood (50 mm), W - stock.
When using 50 mm foam, mounted on a 5 mm adhesive layer, a 110 mm dowel is required. In the case of a curved wall with a skew of 50 mm, the dimension will increase to 160 mm by the corresponding value. A dowel of 210 mm is required for a double layer of insulation.
Excessive length will not always be a positive factor. This must be taken into account when insulating thin walls in an apartment.
Famous manufacturers
The leading manufacturers of insulation dowels are companies from Germany, Russia and Poland. The most famous firms include:
- Termoklip. The company supplies products to Russia and the CIS countries made of anti-rust coated carbon steel. Dowels are produced in several series, made of block polymer. Some models have a heat-insulating cover.
- Isomax. Produces disc dowels with a diameter of 10 mm. The nail is made of zinc coated carbon steel. It is possible to install a thermal head.
- Tech-Krep. The Russian manufacturer supplies plastic fasteners in different versions. They can have a plastic or metal nail, thermal cover. They have a complex chemical composition. The steel nail is galvanized.
All products have the necessary certificates and licenses for installation work.
Installation work
First of all, you need to calculate how many dowels you need, what length and diameter they should have. It depends on the insulation. Its weight is practically irrelevant, the thickness and degree of looseness are important.
The length of the fasteners for the insulation mushroom depends on several parameters. The thickness of the insulation sheet, adhesive layer, vapor barrier, waterproofing. It is also necessary to take into account the deviation from the vertical and the maximum possible deepening into the wall. All these criteria must be specified in the documentation and the size is selected according to them.
The diameter of the cap is determined by the degree of looseness of the thermal insulation. This criterion is approximate, the exact values are not indicated anywhere. If the insulation is light and loose in structure, the diameter should be large. In the case of styrofoam installation, you can choose dowels with a small head. For laying mineral wool, choose the largest hats.
The number of fasteners depends on the weight of the insulation boards and the possible load of the disc dowel itself for fastening the insulation. There should be at least 5 of them per plate - 4 are attached in the corners, 1 in the central point.
All these values are applicable if the interior of the house is insulated.
If the insulation is to be attached to the façade, the wind load must be taken into account. The number of bindings is increasing, there should be at least 6 of them, located in two parallel rows. If the building has a height of up to 20 meters, 1 sq.m. there are 7 dowels. At a height of more than 20 meters, the consumption of fasteners increases to 9 pieces.
Fastening technology
The heat insulator is laid on the surface at an intermediate stage of installation. First, the frame is laid from wooden bars, between which sheets of insulation are placed. The complexity of the installation work lies in the need to take into account all the nuances of the fastening mechanisms in advance. If the ceiling is insulated with plaster, the installation depth of the umbrella dowel should be increased.
The insulation itself is fixed with glue (in the case of polyurethane foam, expanded polystyrene and polystyrene foam) or a crimp into the resulting frame cells (for mineral wool). On each panel, it is necessary to mark the places in which the holder will be installed. A hole of a certain depth is drilled with a margin of 10-15 mm. If you do not add this margin, the fungi for fastening the insulation will poorly hold the thermal insulation material.
A dowel for insulation is installed in the resulting hole. Its head in the form of a disk should slightly press the insulation. If there is a nail, you need to drive it in. In the case of a screw, the screw installation method is used. The head of the fungus is covered with a cap, if provided in the design.
It is recommended to choose the place of joints for fastening. This will reduce the number of holes and slots through which heat escapes. Also, during facade work, all seams are closed with a special aluminum reinforcing tape.
