Characteristics of dowels for fixing thermal insulation. Varieties of dowels for thermal insulation of surfaces with mineral wool and polystyrene foam

Enclosing structures with heat-insulating facades with a thin plaster layer have heat-conducting inclusions, which significantly reduce the coefficient of thermal uniformity and reduced resistance to heat transfer (see the "insulation thickness" section), in addition, they contribute to the moisture regime of the structure. Such heat-conducting inclusions include window slopes, balcony slabs, joints of insulation boards, dowels that fasten the insulation to the wall.

One of the elements responsible for the proper functioning of thermal insulation systems and the duration of operation of facades is dowel fastening.

Structurally, it consists of a sleeve and a spacer element. Three sections are distinguished along the length of the sleeve: a disk holder, an ordinary zone (rod) and a spacer zone. The spacer element has two sections - the head and the ordinary zone.

Application

The main purpose of dowels is to resist wind loads. According to existing standards, the calculation of mechanical fastening is carried out precisely from the calculation of wind loads, taking into account the shape, height and location of the building.

Transferable loads: effects of atmospheric phenomena (primarily wind, as well as temperature changes); the action of shear forces from its own gravity of insulating and related materials; weakening over time, adhesive bond strength due to reaction to temperature influences (thermal expansion of the front panel, large temperature range).

Types of dowels

Dowel with plastic rod used for fastening thermal insulation made of lightweight material, such as expanded polystyrene.

Dowel with metal rod used for fastening all types of thermal insulation, primarily mineral wool.

Dowel length

When choosing the length of the dowel, the following parameters should be taken into account:

• The thickness of the attached insulation
• The thickness of the adhesive layer under the insulation board,
  taking into account possible old layers (for example, plaster)
• planting depth
  (depending on the building material of the wall and ranges from 50-90 mm)

Dowel installation

Doweling is performed as follows:

• drilling holes for dowels with a depth of 10-15 mm more than the anchorage length
• installing the dowels in the holes so that the dowel disk is flush with the surface of the insulation board
• hammering or screwing (depending on the type of dowel) of the expansion element
• the dowel plate disk is puttied with an adhesive solution for gluing insulation boards

The number of dowels for fixing insulation

The number and placement of dowels must comply with the installation diagrams for the respective building heights.

Ordinary zone ≥ 4-5 pcs/m 2

Edge zone ≥ 6-8 pcs/m2

How to choose a dowel

The effect of a heat-conducting inclusion on the thermophysical properties of a structure depends on many factors. The main factors are:

• number of dowels per square meter
• spacer material
• spacer diameter
• dowel head details

As for the assessment of the contribution of the base and external plaster, it can only be noted that the greater the coefficient of thermal conductivity of the materials of the layers framing the heat-conducting inclusion, the greater the influence of this inclusion on the thermal properties of the structure.

The influence of dowels with a metal spacer on the heat loss of a heat-insulating facade with a thin plaster layer (SFTC) or a wall with a hinged facade system with a ventilated layer is very significant and in practically important cases ranges from 7% to 25% of heat loss along the surface of the structure. From dowel elements the design of the dowel head has the greatest influence on the thermal properties of the facade, which is the only barrier to the transfer of heat from the metal spacer to the outer plaster.

In addition, the temperature distribution over the outer plaster depends more on the choice of the dowel. Thermal bridges lead to a rapid drying of the plaster layer above the fixing head and may become visible in certain climatic conditions. These time marks can become permanently visible due to the accumulation of dirt.

When choosing the type of dowel to use in the construction, the problem arises of comparing different facade options. The use of a dowel with increased heat loss will lead to a decrease in the reduced resistance to heat transfer of the facade. To compensate for the decrease in the heat-shielding properties of the facade, an increase in the thickness of the insulation will be required. These provisions are the basis for an economic comparison of thermal insulation system options with a thin plaster layer with different types of dowels.

It should be noted that the greatest energy-saving effect is achieved with the use of dowels, in the design of which the complex technology of a hermetically sealed "heat trap" is used (see table).

Comparative indicators of applications
various types of dish-shaped dowels as part of the SFTK
(expenditure conditionally accepted 8 pcs / m 2)

Dish plug option	Specific heat loss, W/ °C	Specific heat flux, W / (m 2 ° С)	Share of total heat flow, %	Reduced resistance to heat transfer, (m 2 ° С) / W	Heat-technical homogeneity coefficient (r)
Expansion anchor without thermal insulation head
Minimum thermal protection L 1 = 6mm (less than allowed)
Efficient heat shield head 15mm high
Universal energy-efficient dowel with sealing plug

When choosing and designing insulation systems, the material of the sleeve and disc element, as well as their joint behavior with the spacer element under load during operation, becomes a significant factor.

Thus, according to the estimates of the Federal Center for Technical Assessment and a number of independent laboratories and experts, the use of dowels with polypropylene sleeves is problematic, and often unacceptable.

The polypropylene brands used for the manufacture of sleeves and disc elements of dowels have serious drawbacks. The increased ability to relax predetermines a significant decrease in time of the force of expansion of the dowel in the base and, as a result, leads to a decrease in the friction force, due to which the "pull-out" indicators are sharply reduced.

The results of foreign tests carried out on sleeves made of polyamide, polyethylene and polypropylene showed that in less than one and a half to two years (10,000 hours), the expansion force of the dowel with a sleeve made of polypropylene decreases by half compared to the original one, and when using a sleeve made of polyamide and polyethylene - no more than 25%. At the same time, unmodified grades of polypropylene are distinguished by a high brittleness temperature - +10 °С - -10 °С. At low temperatures, its impact strength and strength are significantly reduced, which leads to the appearance of microcracks and more serious damage during the installation of dowels and, accordingly, affects not only the calculated characteristics of local attachment points, as such, but also the entire subsequent operation of building facades. It should also be noted that at sufficiently low temperatures, spontaneous destruction of the supporting section of the disc-shaped element is possible, which ensures tight contact of the insulation with the base. As practice shows, when carrying out the necessary measures to modify polypropylene grades to obtain satisfactory frost resistance properties, a significant increase in the cost of this product occurs.

The use of dowels that are not made of stainless or galvanized steel and / or do not have an additional organic coating, with a metal spacer element during further operation leads to the release of a decorative and protective layer of corrosion products to the surface. Problems of this kind arise due to the fact that the dowel is an element that passes through the entire thermal insulation system, and moisture condensation primarily occurs on the dowel sleeve, and especially on the metal spacer. This often does not take into account the increased aggressive environment created by mineral wool insulation, and the possibility of its access to a metal spacer with a corresponding sharp decrease in service life (up to 5 or less years of operation). The end result of the impact of corrosion on the expansion element will be the complete failure of the dowel fastening, followed by the collapse of the facade.

In addition, the appearance on the market of dowel technology with fiberglass spacers did not allow unequivocally solving this problem. According to some estimates, it is believed that the chemical resistance of the fiberglass rod also decreases over time in the aggressive environment of mineral wool insulation. Due to the wide distribution of dowels with fiberglass spacers, it is quite clear that this assumption requires official verification in order to refute or confirm the problem.

1134 09/18/2019 5 min.

When performing thermal insulation work, fasteners cannot be dispensed with. Today, such fasteners as a fungus have become widespread. Thanks to him, you can tightly attach the thermal insulation and get rid of the cold in the house.

Which one is suitable

When installing a heat insulator, special dowels are used, the name of which is fungi or umbrellas. They securely fix the insulation, and they do it both with dense materials and with fragile ones. Using an umbrella, it became possible to fix the heat insulator to a concrete, stone, brick surface.

Today, an umbrella can be produced in several versions, but plastic products are most suitable for thermal insulation work.

And this is due to a number of advantages:

And although a plastic umbrella is the best suited for installing insulation, it has several drawbacks.

On the video plate dowel for fixing the insulation:

They are also important to consider when choosing a product:

1. Do not use an umbrella with a plastic nail when its length is more than 140 mm. The reason is that long fasteners are not reliable and, so during the installation process, they break and deform.
2. It is advisable to use plastic dowels when fastening light insulation - polystyrene foam, mineral wool polystyrene foam.

But where you can use a wood screw with a countersunk head and how to do it correctly, is described in this

Types and sizes

The design of the dish-shaped dowel assumes the presence of elements such as a core, a sleeve and a wide cap. On sale you can find a threaded mount. They can simply be driven into the surface. Dubemetal or plastic can be used for their manufacture. The cost of such products is 2 times higher than the price of plastic elements. But at the same time they are able to withstand a large load. They are used when attaching hollow and thin heaters.

Plastic elements can be of two types - polypropylene and nylon. The second option can be used when attaching the material to any wall - wood, concrete, gas silicate.

On the video roofing plate dowel:

Taking into account the thickness of the heat insulator, plastic fungi should have different sizes. Today, manufacturers offer a wide range of sizes. The length of the products can reach 70-200 mm, although separate fasteners can be used, the lengths of which reach 395 mm. The diameter of the plastic dowel is 10 mm, but this is enough to obtain the necessary strength.

Hardware

This version of the dish nail also has a certain popularity among developers, because the steel that is used to make the product is much more reliable than plastic.

The advantages of metal dowels include:

1. Reliability. The bearing capacity of the elements is 2 times higher than that of plastic fasteners. The metal dowel is able to withstand a load of 300 kg. You can use dish-shaped elements when installing heavy heat insulators.
2. Wide range of sizes. The width of the hat remains standard - 60 mm and diameter - 10 mm, but the length can reach 90-300 mm. Such dimensions allow you to work with a huge range of heaters. If you need a longer length, then you can make such an element to order.
3. Ease of use. To install the insulation, it is necessary to drive the dowel with a nail. Compared to the plastic version, the metal one is much stronger, so it will not break or bend during an impact. In addition, metal fasteners perfectly burst the dowel, thanks to which it securely fastens the heat insulator.

On the video, the disadvantages of the dish-shaped dowel:

But metal dowels have a number of disadvantages:

1. Metal is an excellent conductor of cold. You can fix this problem if you buy not an ordinary metal element, but fasteners with a thermal head. It is made of plastic, put on a hat and protects the metal from the effects of cold.
2. And although the surface is galvanized, over time, corrosion destroys this protective layer, resulting in brown marks on the facade. To solve this problem, it is necessary to turn again to the option with a thermal head. In such elements, the metal is concentrated far from the surface.
3. Weight of metal dowels much more, since they have metal cores. But especially for the facade there is no difference, although the transportation becomes more complicated.

Type DS-2

This version of the dish-shaped dowel was developed by Russian specialists.

It differs markedly from the previously presented options in the following ways:

The benefits include:

1. There is no cold bridge, so you can not worry about the loss of thermal energy at low temperatures.
2. High reliability.
3. Wide size range. The length of the product can reach up to 260 mm.

The disadvantages of products include:

1. Before installation work, the system is assembled from constituent elements, which increases the installation time.
2. If the nail breaks, then finding a replacement is problematic.
3. Holes must be drilled exactly to the specified depth. If it is larger, then it will not be possible to securely fix the element.

But what are the best drywall screws for drywall, you can find out from this

What should be used and how to do it correctly is described in great detail in this article.

Manufacturers and prices

Today, the following manufacturers of dish-shaped dowels are represented on the market:

The plate dowel is a necessary element for the installation of heat-insulating material. It can be presented in several options regarding the length. For their manufacture, plastic and metal can be used. Each option has its pros and cons, so choosing the right one should take into account the type of heat insulator, the surface to which it will be attached, and the installation conditions.

For the sake of justice, it should be said that fungi for attaching insulation are not the only way to install. But, in most designs, they are used. Even in those situations where, for example, the foam sits on the adhesive foam, with a “wet facade”, a fungus is additionally used for insulation. Let's gradually understand the principles of operation of this "miracle", select the desired type of fastening and calculate the cost.

Dowels for thermal insulation are fasteners consisting of several parts. Namely:

• Hat - its task is to distribute the load over the surface of the material to be fixed;
• spacer element- it bears the load and creates a friction force that ensures the retention of the insulation on the wall;
• Nail - hammered into the expansion element for tight fixation;
• Some types of fungi for insulation have an anchor sleeve for additional fastening.
• Also, there are expansion washers- their task is to increase the contact area with thermal insulation and distribute the load over the surface. In practice, such washers are used for soft materials in order to avoid their deformation.

So, a dish-shaped dowel for fastening is a mechanical element with which the insulation is fastened to the wall.

fastener requirements

Dowels for fastening thermal insulation are subjected to high stress, perform functions in an alkaline environment and are placed in conditions of extreme temperatures. This means that they must meet several criteria.

We have set the basic requirements for fasteners for insulation, now it is important to see how the modern market satisfies these requirements.

Kinds

Simply put, there are two main types of umbrellas.

Made of galvanized steel

The nail of such umbrellas in most cases is made of galvanized steel (sometimes polyamide). And although this material resists corrosion more than other metal ones, it is still not completely protected from it. There is also a second disadvantage. The metal conducts heat well, which means that cold bridges can form at the attachment point and condensation can accumulate. Over time, cracks may appear at the attachment points. This type of fasteners has a higher cost.

Main characteristics:

• Dowel material: impact-resistant polypropylene.
• Anchor material: low carbon, galvanized steel;
• Temperature conditions: -55 - +60 degrees;
• Load: up to 750 kg per square meter.

As a conclusion: such fungi are used in the case of fastening heavy heaters, when the use of plastic ones is impossible.

Made of plastic

Dowel for thermal insulation with a plastic nail. It is used more often than metal ones, but they have a lower cost and lower strength. Although even their performance is very impressive. The temperature regime is from -40 to + 80 degrees. Such umbrellas are also able to withstand a load of 20 to 380 kg per square meter. Nylon nails are also referred to as plastic.

with thermal head

The dowel for thermal insulation with a thermal head is umbrellas with metal nails. A polymer head is put on the end of the anchor. This approach is used for different types of walls, but is especially necessary for wooden ones. The purpose of the head is to reduce thermal conductivity. Such elements have a higher cost (the highest among dowels), but also the lowest thermal conductivity and strength.

In addition, fungi are distinguished by length. This is an important indicator that needs to be calculated correctly. There is also a diameter of the rod under the anchor. Most often, rods with a diameter of 8-10 mm are used.

Price

The price of a fungus for attaching insulation depends on the type and length. Average cost:

The price difference is mainly affected by the length.

You can often find umbrellas in a package of 800-3000 pieces. Wholesale generally plastic are on sale on kilograms. But, for frequency construction, such options are not very suitable. Up to 300 fasteners may be required to insulate one small house.

Length calculation

If the fastener is chosen incorrectly, it will not hold the thermal insulation. And you will have to tear it off along with the attached sheets. How not to make a mistake and calculate the desired length immediately?

The task of the dowel is to fix the insulation to the main wall. This is where you need to get to. On the way to the hard surface lie:

• The heater itself
• The thickness of the adhesive composition (if any).

In addition, it is worth considering that the dowel must enter the wall to a depth of 50 mm.

Thus, we calculate the desired length using the formula:

L = H + I + K + W.

L is the required total length of the dowel;

H is the thickness of the heat-insulating layer;

K - the thickness of the old plaster or adhesive on which the insulation is attached;

I - fixing the dowel in a concrete / brick / wooden base of the wall (at least) 50 mm.

W - margin for the curvature of the wall.

For example, if you use 50 mm thick foam and use a thin layer of glue - 5-10 mm, a dowel 110 mm long is enough for you. If the wall is flat. But, if the wall skew reaches 50 mm, it is worth adding this indicator and then you need a dowel of 160 mm or more. If we increase the thermal insulation layer to 100 mm, in the latter case we need 210 mm of the rod length.

In choosing fasteners: longer is not always better. If insulation occurs, for example, in an apartment, the thickness of the walls can be especially small and the length must be calculated correctly.

Mounting schemes

In the first approach, 5-6 dowels are needed for 1 square of material (as a rule, it is approximately equal to 1 square meter). 4 are fixed in the corners (5-10 cm from the edge) 1-2 in the center.

According to the second scheme, the dowels are driven at the junction of two plates. Thus, one hat holds three plates at the junction. With this approach, one dowel must be hammered in the center.

Folk craftsmen, for the sake of the notorious economy, manage to get by with one dowel on the stove in the center.

When determining the number of fasteners, it is also necessary to take into account the number of storeys of the building and the place where the insulation is attached. At the corners, more fasteners are recommended. On buildings above 8 meters, 7 mounts per square. On buildings above 20 meters, 9. This is due to the increased wind load and the load on the lower rows of thermal insulation from the upper ones.

Installation

The use of a dowel for fixing insulation occurs in 3 stages:

• A hole is drilled corresponding to the diameter of the rod and exceeding its length by 10 mm;
• A dowel is inserted manually (its cap should be flush with the insulation);
• A fixing anchor is inserted and hammered.

If you are using an expansion cuff, you must put it on before inserting the fungus!

If available, cover the hat with a lid.

Additional heat losses through point heat engineering inhomogeneity are the result of calculating the temperature field. ...Then the question arises: under what [b]input data were the indicators indicated in Table 9 TO THE THERMOCLIP-a obtained? And as a post factum, they [b]cannot be used for reference when calculating the "pie" of the SFTC for the new JV. Yes and no, and I even took the liberty of bolding your text. Unfortunately, without the permission of the copyright holder, I will not fully lay out the NTO NIISF with the calculated specific heat loss through various options for WALL dowels for various reasons. The interest, however, is in the trends (see page 1 of the pdf-file)... 1. Initial conditions: - base thickness 200 mm with three fixed points by the coefficient. thermal conductivity 2.04, 0.64, 0.18; - conditions B; - MVP 150 mm; - Nar. plaster 6 mm; - outdoor temp. -28 C; - ext. pace. 20 p. 2. The plate shows a slight change in specific heat loss through the dowel practically from reinforced concrete to cellular concrete. The temperature difference on the outer plaster is also small, which is also very important during operation. 3. However, I do not agree with your verdict and I think that it is quite possible to use this plate for reference when taking into account heat losses through dowels. I have been interested in this issue with the Germans for many years, it seems that we have come to the same understanding of this topic (see, as an example, sheets 2 and 3 of the pdf file). So already (I at least) threw 5% on the losses on the dowels during calculations (purely "by eye" since there are no methods) ... Yes, I agree, with a dowel with a correct and good break of the thermal bridge (Fig. 2 and 3 ) and scheme 5-7 dB/m2. Yes, we do not have any calculation methods on this topic. I will say more when the well-known graphs appeared for a significant decrease in the coefficient. thermal engineering homogeneous vents depending on the material, section and number of crowns. subsystems per m2, I brought to the NIISF photos 46 of the tax, where, in addition to all the charms of the aluminum subsystem, they managed to score 9-10 dB on the MVP (why!) c metal. core and metal. sleeve (!). Plus he brought several German books on this topic. After the calculations, some well-known people at NIISF experienced a completely understandable shock ... from their own underestimation of heat loss through dowels. I think, without straining, you can easily make not an insulation system, but a decorative cladding from a vent. Although, we must pay tribute, serious vents have become much more careful in choosing a dowel. However, the main thing is different. If the Thermoclip dowels, like the pioneers, push the respected FCS to take the dowels more seriously, then we will automatically solve another important problem along the way. The problem of moisture condensation in the places where the dowels are installed. Yes, those same, known to all, dark and light spots. Yes, the same homogeneity of the outer plaster layer. P.S. It is interesting that earlier, when making estimates, I attributed the driven dowel STEN to fig. 2, and he even got into fig. 3. Believe? Perhaps yes. I used a hacksaw to scrap a lot of metal. nails with thermal insulation. a head from various dowels that roam on our market in order to find out where the nail head is really located and what is the real thickness of the thermal bridge gap ... P.P.S. Yes, and anticipating possible rumors, I will say frankly and firmly, I am not an adherent and / or lobbyist for Thermoclip dowels. Simply, in my opinion, today in Russia there are only two dowels, Thermoclip and Biysk, which are practically not inferior to imported dowels. Sometimes it even hurts to look at some of the others ... Although I can’t do it without a fly in the ointment. In the same fresh TO of Thermoclip in clause 2.13 we read: "... In facade systems with a thin outer plaster layer, dowels can only be used to transmit wind influences (suction). The self-weight of the heat-insulating system must be perceived by the adhesive composition." The reliability of SFTC through dowels, as it seems, in principle, cannot be considered separately from the dead weight of the system.

When starting the process of building insulation, the primary task is to purchase suitable type materials. The purchase of a high-quality thermal insulation coating is certainly important, but you should not neglect the careful selection of fasteners.

These tiny details largely determine the success of the work done. Today, dish-shaped dowels for thermal insulation are in special demand in construction, they are the ones that are able to ensure the correct and reliable fixation of the insulation, so that your home will get rid of the cold forever.

Modern fasteners differ significantly from each other. Before proceeding with installation work, we recommend that you learn about the features and rules for handling dish-shaped dowels and others.

1 Purpose of fixing dowels

Dish-shaped dowels are very much in demand in construction, they are often used to attach insulation to the facade of buildings. These elements are able to equally effectively hold both hard and soft plates of heat-insulating material on the wall, and also provide reliable fixation of a loose and fragile coating.

The dowels are strong and "hardy", they can be used for mounting insulation on surfaces made of concrete, brick, aerated concrete, foam concrete or building stone. This versatility makes fasteners more and more popular among buyers.

1.1 Structure and material of production

1.2 Types of dish-shaped dowels

There are several types of plate-shaped dowels, depending on the scope of use, the differences between them lies in their design.

The following types of fasteners are available on the modern market:

• dowels with a metal core;
• dowels with a plastic rod;
• dowels with a thermal head.

Dowels with a metal core are used to attach a layer of insulation to concrete masonry, solid brick, as well as when installing a thermal insulation system for ventilated facades (creating, for example).

The metal rod is able to withstand enormous loads, due to which such dowels are often used when assembling heavy structures. In addition, such fasteners are indispensable when working with hollow and thin-walled surfaces.

Dowels with a plastic shaft are ideal for fixing a thermal insulation layer (foam, polyurethane, glass wool) to foam concrete, concrete, wood or foundation slabs. Fasteners with a plastic core are less durable than those with a metal base, which explains their affordable price.

Dowels with a thermal head are used to fix the insulation board to the plaster facade. A special tip prevents sweating of the anchor part of the fastener through the decorative or reinforcing surface layer.

2 Application of fasteners (video)

2.1 Installing the plate dowels

Working with dish-shaped dowels, as well as with it, is quite simple. It consists of the following steps:

1. Marking the area for mounting the insulation layer.
2. Drilling holes through thermal insulation material.
3. Installing the dowel in the landing socket until the hat is sunk into the wall.
4. Installing a nail to spread the insulation layer and hammering it to the required level.
5. Nail head attachment.

Adhering to the sequence of all operations, you can quickly insulate the facade of the building.