The brick has high level water absorption. Therefore, when facing a house with brickwork, ventilation gaps are made for weathering. excess moisture. Thermal insulation properties brick walls not high enough, and in order to create comfortable conditions for living, insulation is prerequisite when constructing houses from this building material. When using the method of three-layer masonry of load-bearing structures with internal insulation They also leave gaps for ventilation.
What are clearances and why are they needed?
By gaps we mean the distances between the walls, which promote ventilation and prevent the accumulation of condensation inside the structure. In such gaps you can place thermal insulation material for insulation. With this method brickwork outer wall the house consists of three layers:
- Load-bearing structure.
- Insulation.
- Facing.
It is used to increase the thermal insulation of a home and to save energy resources. Thermal insulation material inside the structure it protects the load-bearing wall from freezing. In addition, it itself is reliably protected from damage. And the existing air gap between the insulation layer and the facing masonry promotes ventilation and evaporation of excess moisture.
Process technology and gap sizes
The width of the hole should not be more than 2 cm.
Masonry begins with the construction of a supporting structure. Then they lay out the wall facing bricks, leaving a gap between them for air circulation and, if necessary, for insulation. The distance should be 1.5-2 cm or within 5-15 cm in the case of thermal insulation and depending on the thickness of the material layer. An air cushion is made in order to exclude deviations from the norm in the vapor barrier indicator.
The vapor permeability of all layers must be combined. This will help prevent moisture from accumulating on the internal sides brick structures, which will prevent the formation of mold and mildew, as well as preserve the heat-shielding properties of the insulating material and extend its service life.
Regardless of the presence of insulation inside the wall, for air circulation between load-bearing structure and make special gaps in the form of embroidered vertical seams in the facing masonry. They are located at the top at the eaves and at the bottom at the plinths of the building. The number of such holes depends on the size of the walls, and their width is 2-4 cm.
Gaps when insulating brickwork
The choice of insulation depends on the material of the external structure of the house, since the vapor permeability coefficient of elements of all layers should be taken into account. As insulation you can choose:
You can insulate the wall using polystyrene foam.
- mineral wool;
- expanded polystyrene;
- bulk insulation.
When using insulation in the form of slabs, all structural elements are fastened together using flexible connections that are installed on a load-bearing wall. Afterwards, the facing masonry is laid out to their level and heat-insulating material is placed on them. Waterproofing is attached to the insulating layer and a gap is left for ventilation. To create it, use connections that have a plastic washer with a latch. It presses the insulation against the wall and prevents it from slipping and deformation. The width of the air cushion varies within 4-6 cm. Bulk insulation simply fills the void formed between the walls without creating air gaps, after the height of the walls being built reaches a meter.
Why are these air gaps between the brick and the brick really needed? load-bearing wall?
First, we need to emphasize that the facade of the house can be either ventilated or non-ventilated. Now let's take a look at the picture, and then I'll explain everything:
Now I'll move on to the explanations. Ventilation façade is a wall structure in which it is possible for air flows to circulate freely between front part walls and load-bearing, from the base, which stands on the foundation and ends with an unobstructed exit into the atmosphere, as shown by the arrows in the figure.
Since we are considering a wall with brick cladding, in our case for normal air circulation it is necessary to leave unfilled seams in the first row as shown in the figure above. This helps fresh air flow inside the wall. The distance between each hollow joint should be 1 meter. The following sequence is obtained: having penetrated through the cracks of the first row of brickwork, the air blows out moist or heated air in the air gap through the top onto the roof and then onto the street. Their list includes wood, foam blocks, aerated concrete blocks, mineral wool, fibrous and other materials
Let's note one big mistake all builders. The air gap should not overlap, that is, nothing should interfere with its free air circulation, right up to the very top row of bricks of the building under construction. And all the air should freely go outside. Some, approaching the end of construction, make a wet screed, blocking the air gap. This is not right!
During the cold season, in any heated room there is an increased concentration of moisture, which goes out into the street through the walls of the house and, accordingly, through the insulation, which leads to the formation of condensation on their surfaces. This leads to the destruction of the building material. Plus, when wet, the wall material retains heat less well, which leads to unnecessary heat loss. In this case, the air gap plays the role of a temperature and moisture concentration regulator. It turns out that the load-bearing wall with insulation evaporates water and nothing prevents it; moisture enters the air gap and escapes into the atmosphere through the upper gap. It turns out that our wall remains dry and unharmed, and this prevents rapid rotting and decomposition of the building material.
But every reasonable person will say that this is excess heat loss in winter period! What to do?
You know. On many forums they write that external facade masonry still does not provide anything in terms of heat conservation. I just want to shout in their faces. This is not true. Many people write this out of a lack of understanding of the matter. I'll ask you a counter question. What can you say about the brick walls in residential buildings? Don't they conserve heat either? Tomorrow I will begin to dismantle my house and dig a dugout for myself. Of course, I’m exaggerating this, but brick walls are excellent heat-saving structures. Judging by the school grading scale, a 50 cm wall saves heat for a grade of 5+, a 25 cm wall for a grade of 4, and a 12 cm wall saves heat with a C minus. But again, we came to the conclusion that it still keeps warm. And this does not give us any right to say that lining a wall with brick will not retain heat.
So here are my recommendations. If you are building a house in which the load-bearing wall will be made of wood or from a material that, when wet, does not retain heat well or begins to lose its strength and fall apart, such as wood, gas blocks and mineral wool, then of course make an air gap between the cladding and load-bearing wall, and also do not forget to leave empty seams in the first row for admission fresh air. But then, in this case, you will need to make the main wall wider or better insulated, so that you no longer have to think about the fact that you will have to burn excess fuel for heating, because the heat will also erode from the air layer with moisture.
If you are building a house from a material that is not affected by moisture in any way, then you shouldn’t even worry about ventilated facades. Do it without air gaps! And if you do, you don’t have to leave any empty seams in the first row, this way you will better retain heat.
In addition, I want to highlight several features and useful points:
1. The size of the air gap between the load-bearing wall and the facade structure according to SNIPs and GOSTs should be 1.5-2 cm. I think that they took into account ideally flat wall without possible deviations, which is precisely designed for the layout of bricks or wall panels and their material was simply the most ideal. But this is nonsense, I want to tell you, comrades! In practice, it is very difficult to calculate everything and the air gap is usually left depending on the situation, about 3-5 cm.
2. In construction, an air gap helps hide all sorts of flaws in the wall. A wall that is surrounded by brick does not require any intervention. That is, all the defects and irregularities that exist will remain in this air gap. They will not need to be leveled, cut down, cleaned, and if they are needed, then only the slightest intervention. I think this is such a big plus.
3. The following advantages are related to weather events. In the heat of summer, the brick in the sun heats up to enormous temperatures (can reach up to 90 degrees Celsius), at this time the air gap acts as a temperature regulator, because the heated facing brick shares its heat not with the load-bearing wall, which transfers all the heat inside living space, but with an air gap, which subsequently carries away all hot air into the atmosphere. This helps keep your home cozy and cool in the summer and you won’t need extra costs for air conditioners and fans. This means that a material that releases gases when heated and is capable of destruction will be protected. An example is concrete blocks and a tree.
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When finishing or reconstructing a facade, as a rule, its insulation is done along the way. In pursuit of the best thermal insulation, the customer often forgets or ignores the most important indicator insulation - vapor permeability. This is fraught with big problems: getting wet, freezing and premature destruction of the load-bearing wall.
Ventilation holes in the facing masonry are necessary to maintain an optimum temperature and eliminate the “greenhouse effect”, which significantly accelerates the destruction of walls. Therefore, every 3-4th vertical seam in each row facing masonry should not be filled with solution. These will be the ventilation ducts.
The principle of condensation formation explains how this happens: at the point of contact different temperatures(cold and heat) moisture accumulates on hard surfaces. This often becomes the cause of “ice walls” or damaged interior decoration. The only way out is to provide moisture with the opportunity to freely evaporate into the atmosphere, i.e. outside the building.
It is also necessary to leave air vents at the top and bottom of the cladding.
In this regard, when constructing facades using the “wet” method (applying mortar finishing layers), vapor-permeable compounds are used. In another case, a ventilated facade system is used.
Wall ventilation, which is placed under the brick - this is a very important part of the work process. If the cladding is carried out by professional masons, then this process will not take much time, but if you want to do everything yourself, then you need to take into account several important points:
- All rows of stones are laid using mortar, but the 34th row is installed without it, this will help ensure natural ventilation walls. Sometimes this type of masonry is not suitable and you can leave an air cushion between the roof and the wall;
- The ventilation gap should be at least 25 mm, but this is for a wall that is completely flat. When facing wooden house from the timber you need to maintain a gap of 30 mm;
- If the gap is under the beam, then it can be closed using a special strip, without laying a row of bricks.
If there is an air gap in the walls of your house, then there must be ventilation boxes!
The main advantages of ventilation boxes:
- Ventilate the air gap
- Protect the wall from rodents and other pests
- Protects from precipitation (especially during intense side rain)
- Discharge condensate outside
- Matched to the color of the masonry, they are almost invisible, which does not spoil the impression of the facade
Ventilation and drainage boxes
Ventilation and drainage boxes used in ventilation system facade. They come in two types: and a ventilation and drainage element for a 10 mm seam
Facade ventilation system it is quite simple to create and consists of only two elements: an air gap 10 cm wide with a distance between the heat-insulating layer and the façade layer of 4 cm and ventilation holes - vertical seams between the bricks that are not filled with mortar, into which the ventilated elements of the facade are mounted.
Before startingsoundedand I the first row of masonry must be laid with waterproofing (an apron made of bitumen mass), along which condensate will flow freely through ventilation holes out. Similarly, waterproofing should be laid over each opening of the building.
Ventilation holes located in the first and last rows of brickwork. If the wall height is more than six meters, another row of ventilation holes is additionally located in the middle of the wall. At the same time, the distance from the corners of walls and openings to the first ventilation hole should not be less than 25 centimeters.
Horizontal holes placed at a distance of 1 meter from each other (every 4 bricks). At the same distance, ventilation holes are located under and above the openings, but at least two holes for each opening. Vertically, the holes are placed directly above each other, and in no case in a checkerboard pattern.
Proper placement and installation of fans guarantees them effective application, which means long-term preservation of reliability, strength and ideal appearance your facade.
Location of ventilation boxes
Advantages of ventilation boxes:
- Drying inner surface facade, which ensures its durability.
- Salt stains do not appear on the ventilated façade and mold does not form.
- The insulation is drying out. Only dry insulation meets all thermal insulation requirements.
- According to studies conducted in Germany, thermal resistance walls with a ventilated air gap are 6% higher than a similar wall without an air gap.
Distribution of ventilation boxes:
- Ventilation boxes are installed in the vertical joints of the facing masonry with a frequency of: 1 ventilation box - 2-3 bricks
- In buildings up to two floors - 2 rows of ventilation boxes (at the bottom - in the first row of masonry, and at the top - in the last) If the wall insulation turns into insulation pitched roof- in this case there is only one row of boxes - in the first row.
- In multi-storey buildings - an additional row of boxes every two floors.
- Additional ventilation boxes are installed above and below the openings
- The ventilated air gap should be within 30-50 mm.
- At the junction of the foundation and the walls, not only horizontal, but also vertical waterproofing to a height of at least 150 mm must be provided. (according to DIN 1053 T1).
Is the ventilation box a cold bridge?
The ventilation box cannot be a cold bridge. The ventilation box is mounted in the body of the facing brickwork and does not in any way disrupt the continuity of thermal insulation (the facing brickwork in multi-layer walls freezes and does not perform a heat-insulating function). As a rule, in three-layer or two-layer walls, where the façade is faced with facing or clinker bricks cold bridge are galvanized anchors or masonry mesh, acting as horizontal connections.
Why is a ventilated air gap needed in two-layer or three-layer walls?
For walls made of vapor-permeable materials (such as ordinary brick, aerated concrete, foam block, ceramic block and shell rock) ventilation gap is a mandatory element of façade ventilation.
The ventilation gap in the wall performs following functions: - removes condensation from thermal insulation (three-layer walls) or load-bearing wall (two-layer walls), thanks to this the materials retain their original thermal insulation properties; - prevents the appearance of efflorescence on the facing brickwork; - creates favorable microclimate indoors.