- What requirements do we put forward for the perfect facade finish
- What is a ventilated facade
- Advantages of hinged ventilated facades
- Disadvantages of curtain walls
Until recently, for some reason, the concept of “ventilated facade” remained outside the scope of my attention. No, I, of course, constantly came across this phrase, but somehow I did not ask myself the question of what is a ventilated or, as it is also called, a curtain facade.
I think it’s time to fix this omission. If you enter the word “facade” into a search engine, almost all the sites shown will contain an offer of these very ventilated facades. Since there are so many offers, we must take! But why? Why is a ventilated facade good and is it good at all? We will find out.
What requirements do we put forward for the perfect facade finish
- Mechanical protection
- Thermal insulation
- Moisture protection
- Aesthetic appeal
- Simplicity of the device
- Affordable price (well, since we’re talking about ideal)
So let’s see, based on these requirements, how ventilated facades are close to ideal. But first, let’s figure out what this modern technology of exterior decoration of buildings is..
What is a ventilated facade
The ventilated curtain wall is a complex structure consisting of several layers:
- outer screen made of cladding material
- sub-facing supporting structure (lathing)
- ventilation (air) gap
- thermal insulation layer
Air gap – the main condition for a correct ventilated facade.
An air spacer is required between the cladding screen and the thermal insulation. This is the main feature of the ventilated facade. It is thanks to this air gap that condensation and atmospheric moisture are removed from the facade surface. In addition, such an air gap can significantly reduce heat loss, because the air temperature inside the structure is three to four degrees higher than outside.
The distance between the thermal insulation and the protective screen must be at least 20 millimeters. Compliance with this condition is extremely important. With a smaller width of the air gap, moisture will not be removed as it should, and this, in turn, will lead to wetting of the thermal insulation, an increase in heat loss, an increase in humidity in the room, an increase in the weight of the thermal insulation material and, as a result, even its collapse..
When installing a curtain wall, it is necessary to ensure free movement of air flows between the thermal insulation and protective layers. There should be no obstacles to the air, neither above nor below the facade. In order for the air to circulate freely, special perforated metal elements are used, installed in the upper and lower parts of the structure..
A variety of cladding materials can be used for the protective screen of a ventilated facade:
- fiber cement boards
- volumetric panels or cassettes made of metal for each project individually
- a natural stone
- fake diamond
What material you choose depends not only on the appearance of the building, but also on the quality of the entire structure, because the function of the external screen of the ventilated facade is to protect the thermal insulation layer from mechanical damage, wind, moisture, ultraviolet radiation. We will not consider the performance of each of the facing materials, this has already been done in sufficient detail in another article. We only note that each material has its own parameters, which determine both the appearance and performance of the facade, and the features of installation.
The elements of the outer cladding are attached to the batten (supporting substructure) in two ways – by visible and invisible fastening. In the second case, the cladding elements are fastened using special grooves on the inside, so that the fasteners remain invisible. The invisible method of fastening the cladding allows for greater aesthetic appeal, but it is more expensive than the visible one. But the visible method also has its pitfalls. With a more attractive price of this method, it should be borne in mind that if it becomes necessary to replace one facing fragment, the entire row will have to be removed. Often, these two methods are combined: on the lower floors – at a height of 4-5 meters – they use the invisible fastening method, and above they use a simpler option – visible fastening of the facing elements. In order to close the structure from the ends and at the corners, various inserts and corners are used, which allow you to achieve the external completeness of the ventilated facade.
The supporting structure or lathing is perhaps the most technologically complex element of the curtain wall system. The fact is that it is not enough to fix the brackets on the wall and attach metal profiles to them, on which the cladding elements will then be hung. It is important to properly design the batten and calculate its bearing capacity – the substructure must withstand its own weight, the weight of the protective screen and insulation. At the same time, it must have sufficient anti-corrosion resistance, be durable and not too difficult to install. Conventionally, all possible options for supporting structures of hinged facades can be divided into two groups:
- lathing for cladding, which has a relatively low weight (siding, cement fiber sheets, corrugated board, etc.)
- lathing that allows the use of heavy materials (natural or artificial stone) as cladding.
Insulation used in curtain wall systems must also meet a number of requirements. It must have a sufficient density – from 80 to 100 kg / m3. Otherwise, over time, the wind will begin to tear off pieces of material, which will lead to a decrease in the thermal insulation capacity of the facade. In addition, the insulation must be fire-resistant, durable, and have good soundproofing qualities. Most often, mineral wool is used for these purposes..
Now, knowing what a ventilated facade is, you can consider its advantages and disadvantages.
Advantages of hinged ventilated facades
The scope of application of curtain walls is more than extensive. Today they are used on buildings of almost any purpose: administrative, residential, industrial. In addition, the installation of curtain facades is justified both in the construction of new buildings and in the restoration of old buildings. The only caveat is that curtain walls usually don’t look good on low houses. Therefore, from the point of view of aesthetic feasibility, their arrangement is justified on buildings with more than three floors..
Installation of hinged ventilated facades is relatively simple and, most importantly, it can be performed at any time of the year, unlike the implementation of wet facades.
The installation of curtain walls does not require special preparation of the outer surface of the wall, as is the case with plaster, painting or fixing the cladding with glue or cement mortar. On the contrary, curtain facades will hide various defects of the enclosing structures and will even be able to compensate for the disturbed geometry of the building within certain limits..
Due to the presence of an air gap, the heat-insulating qualities of the exterior finish are significantly increased, and the resulting “exhaust” effect allows you to remove excess moisture and avoid its accumulation in the insulation layer and in the wall itself.
The materials used for external cladding of curtain walls are resistant to aggressive mechanical and atmospheric influences and protect walls, insulation and supporting structure from them, thereby prolonging their service life. In addition, the very design of curtain walls allows you to absorb thermal deformations that invariably arise due to daily and seasonal temperature fluctuations. This prevents material stress and, as a result, cracks and other damage to the cladding and the supporting structure..
Curtain facades have a special aesthetic appeal. They are able to decorate a building, besides, their appearance is very diverse, which allows you to implement various design ideas.
Disadvantages of curtain walls
Against the background of such an impressive list of advantages of hinged facades, their shortcomings look somehow unconvincing, but they are still there. First of all, the fact that ventilated facades are quite expensive today should be canceled. In addition, all the advantages of a ventilated facade can come to naught if mistakes were made in its design. Therefore, all stages of the project should be entrusted exclusively to professionals – it will not work to save money on performers. I would include another drawback here – not long enough service life. Yes, the projected lifespan of ventilated facades is 30-50 years. I would like to stay longer. You do not find?
As you can see, there is nothing super complicated in the curtain wall system. She, like everything ingenious, is simple. Of course, the ideal was still not achieved, but the one who invented the curtain wall system managed to get very close to it. It remains to wait for a decrease in prices for this type of facade decoration.