What could be more complicated than repairs, not even current ones, but capital ones? That's right, building a house. There are much more problems here, but there are no options to consider, and when you have to choose one thing, there are no different solutions and forks. So you will have to work hard to ensure that the house has stood for a long time, and during the entire period of its operation does not leak, the windows are not blown, and the foundation does not collapse under the weight of the building. But today there will be a conversation about something else - about one of the final stages, in fact, of the building. That is about the roof. And more precisely, on how to lay a vapor barrier on the roof.
What is vapor barrier?
As a matter of fact, the production and use technology is simple to impossibility - another additional layer of material is put into the roof, which does not allow moisture to pass through. A vapor barrier layer is usually a film made from several types of materials, which will be discussed a bit later. So, as you can see for yourself, there is nothing super complicated about this.
Why do you need vapor barrier?
A little higher was said a few words about the long operation of the house.
So, in order for the roof to serve for a long time, you should think about its vapor barrier. This is not done so that moisture does not get into the house from the outside, as you might think, no, here it is all about water vapor that rises up from the inside. Modern materials that are used for roofs are quite capable of retaining heat well and not let water inside the house, but nothing protects them from getting wet from the inside. For these purposes, you need to use an additional layer of material that does not allow water vapor to the upper layers of the structure and prevents them from deteriorating. That's why vapor barrier for the roof is needed.
Roof seat
In the construction "jargon" you can find such a thing as a roofing cake. This is because the roof is just something like a pie. That is, many layers of different materials overlap each other - they all play different roles, and therefore none of them should be excluded. It can cost you anything, up to an early complete replacement of the roof, but you certainly do not need it. There is no pleasure in such works, especially since they are completely meaningless.
The vapor barrier for the roof of the house is installed as the lowest layer of the roof. From top to bottom, the diagram will look like this:
- roofing;
- crate;
- waterproofing;
- insulation;
- rafters;
- vapor barrier.
That is, this layer is vital to protect everyone else - if it is not in place, mold will form inside the roof, materials will begin to deform and collapse. All this can even lead to the collapse of the erected structure.
Vapor barrier of the roof. Materials
Today, the construction market is extremely developed, and therefore it is almost impossible to find the right material for anything. Moreover, it does not require anything too special. The same materials that are used for waterproofing are quite suitable. So you can just buy more plastic film and use it not only in the middle of the “pie”, but also below. This method is much simpler than the rest. In addition, you can also buy a polypropylene film or even a membrane. About these three species a little lower and separately. In addition to them, there are others, but not so common, for example, isospan, although it is quite promising.
Polyethylene films as vapor barrier material
This is the most easily accessible component of all that can be used as a vapor barrier for the roof. Moreover, as has already been said, it is universal. However, for greater structural strength due to the lack of special properties of rigidity and density, it will be necessary to use films with a reinforced fabric or mesh.
Such films are produced in two different types - perforated and non-perforated. The former are used only for waterproofing the roof, but the latter are for your current purpose. The fact is that perforated films are made with holes, which makes them unsuitable for vapor barrier. At least theoretically. In practice, such a film can also be used as an insulator.
Polyethylene films are produced in rolls, and so you will stack them - for this reason, you should pre-attend to the purchase of sealant. This is absolutely necessary to create a vapor-proof curtain, the role of which this film will take on.
Polypropylene films
This type is mainly used for waterproofing works. Nevertheless, it is sometimes used for vapor barrier, but only when nothing else is at hand. Otherwise, it is better to get a different look.
By design, they consist of two layers. One of them is a combination of viscose and cellulose, which is used to absorb excess moisture and then dry.
Membranes Characteristic
This material is quite expensive, but it is understandable - it is much more modern. In fact, membranes are closest to perfection, that is, to complete vapor barrier of the roof and protect it from external influences. However, using them for this purpose will be quite unreasonable - waterproofing is much more suitable for them, especially for two-layer specimens. These models (not only two-layer, but to a greater extent) are interesting in that they do not allow water to pass through, but allow steam to pass through, which then lingers in the upper layer and evaporates.
Do-it-yourself vapor barrier for the roof
Of course, it is always much easier to call specialists and let them do everything. This provides a sufficient guarantee of quality, and also does not have to work hard for the invisible after the result. But if you still want to make a house from top to bottom yourself, then the tips given here should be useful to you.
It is best to disassemble it using the example of isospan - it is quite easy to lay films, and instructions can be found almost everywhere. In addition, the technology for laying the vapor barrier is almost the same here, the differences are only in small details.
Necessary tools
Of the tools that are needed to install a vapor barrier, you only need a construction stapler. If he is not at hand, do not worry. It is possible to do with a hammer and a certain amount of nails. The latter, by the way, are best taken galvanized.
Materials
In addition to isospan, whose properties are described above, you will need the following materials:
- Adhesive tape - for sealing joints and various joints.
- Sheathing - is used as a decorative element so that the vapor barrier layer of the material is not visible. You can make such a covering from OSB boards, drywall, lining, MDF, etc.
Installation process. Scheme
The vapor barrier for the roof is laid in a certain pattern. As you remember from the previously submitted information, it is located at the very bottom and is attached to the rafters. For this first step, a construction stapler or nails will be used.
Izospan is produced in the form of rolls, therefore, in the corners, as well as at vertical and horizontal joints, it is necessary to overlap. This will help to prevent steam leakage into the insulating layer.
The last installation step is to fix the resulting layer with the previously mentioned adhesive tape. All joints, corners, places of abutment of the material to the walls should be carefully glued with such a tape. Such a thorough approach is needed to seal any possible passages.
In addition, if you sheathe the vapor barrier from above with decorative material, you must leave a gap of about five centimeters. This will allow ventilation.
Ceilings: Do you need a vapor barrier film?
In fact, vapor barrier of ceilings is the same necessary process as vapor barrier of a roof, especially if your structure is assembled from wood. Here humidity becomes generally a critical indicator. In addition, this is necessary if there are bathrooms and bathrooms below - there will always be more moisture there than in the rest of the house. This also applies in part to kitchens. Also, the floors between the basement and the first floor are often equipped with a vapor barrier - especially if the rooms are heated. The accumulation and evaporation of condensate in this case is inevitable, which makes the installation of vapor barrier mandatory.
Vapor barrier: to do or not to do?
Here the answer is clear - to do. The second option is fraught with serious consequences. In fact, there is nothing particularly complicated in this process, and therefore it is not worth neglecting it, as well as not paying attention to small details that can subsequently become decisive.
It should also be noted that vapor barrier for the roof, the price of which is not so high, especially compared to other matters and materials necessary during construction, is accessible to many. So, films will cost you about one and a half thousand, but these are the cheapest (from 660 rubles per roll). The better the material, the higher the price. For example, the most expensive membranes cost about seven thousand rubles.
The price indicated here corresponds to 75 m
2 of film, which is quite enough for one average house.