Roof membrane - which is better? Review + Video

Roof membrane - which is better? Review + Video Characteristics of the under-roof waterproofing membrane. In this article, we will talk about the main properties of materials present on the construction market that will protect the roof from moisture, namely, roofing films and a membrane.

In order not to be mistaken with the choice, you should consider the features of choosing different types of membrane, depending on what type of roof and roofing will be used.

Recommendations for choosing a membrane

Vapor barrier films

This type of film is used in houses where the roof is insulated, to isolate the insulation from vapors that begin to rise from inside the house. It is very important during installation that all joints of the vapor barrier are tight.

In the joints of a non-hermetic type, moist air from the room will enter the heat-insulating material and worsen its properties. When choosing a material, you should pay attention to such an indicator as the vapor permeability of the material. It will indicate how many mg of water vapor will pass through a film with an area of ​​1 m 2 in 1 hour (taking into account that the air temperature is the same on both sides of the film, and the vapor pressure difference is 1 Pa). The lower the vapor permeability number, the better the vapor barrier is considered.

Perforated waterproofing films

This material can be used for any kind of roofing.

Please note that waterproofing perforated films have lower vapor permeability, therefore, during installation, be sure to make 2 gaps for ventilation.

The material has a number of advantages:

  1. Roof membrane - which is better? Review + Video Reasonable price. But it is still worth checking whether the roof structure will actually be cheaper using this film than roofing using a membrane. As indicated, such films can only be successfully used if there is a ventilation gap. The bottom gap will be designed as an additional sheathing to be installed over the rafters.

    It turns out that more wood will need to be used. In addition, you will need more consumables - fire retardant, antiseptic, fasteners, as well as additional installation time.

  2. Savings. Such a film is the most profitable (except for the under-roof membrane) option for arranging the waterproofing of a pitched roof, as it will protect the thermal insulation layer from moisture. If the membrane is laid, then part of its functions will not be used, and the perforated mesh is the best option for such a roof in terms of price-quality ratio.

The disadvantages include the following:

  1. If the roof has a complex shape, for example, transitions, skylights, several valleys, then sometimes it is not easy provide a free ventilation passage for air flow. In this case, there is a threat that the moist air will not be able to completely disappear from the insulation, and remaining in it, moisture will lead to the appearance of mold and mildew.
  2. Such films are more difficult to install than a membrane, since it will require the arrangement of an additional sheathing for insulation.

Hydrofilms with anti-condensation coating

Such films are used for metal roofs - with metal tiles and folded roofing. Now about the installation.

The film has a fleecy side, which perfectly absorbs moisture and prevents it from getting on the inner surface. For this reason, good ventilation of the roof space is required. This will require making a lower ventilation gap.

Please note that such films help to protect the inner surface from moisture, but will not be able to protect against condensation in summer, when moisture begins to penetrate under the roof from the outside during hot times of the day and cool at night.

Diffuse under-roofing membranes

Membranes MUST NOT be used with roofing materials that have a high thermal conductivity.

The only exception is special volumetric membranes. It is installed on the roof of complex shapes, since it is extremely difficult for them to make the lower ventilation gap using another crate. One top ventilation gap required (this saves materials as no additional lathing is required).

How to choose shingles

Soft (bituminous) shingles

As insulation, you can use a diffuse under-roof membrane with one ventilation gap or PP / PE waterproofing film when making two ventilation gaps. The rafters are also installed, and then the waterproofing, control lathing, simple lathing, flooring, tiles, thermal insulation material and vapor barrier are laid.

Metal tiles (without acrylic coating from the inside)

Roof membrane - which is better? Review + Video For waterproofing, an anti-condensation film is advised, since the metal has a high thermal conductivity and condensation begins to form on the lower surface of the metal coating with a daily temperature drop. Ordinary waterproofing films can also be used. Only special volumetric diffuse separating membranes can be used.

To remove moisture between the waterproofing and the metal tile, create an upper ventilation gap with a height of 4 cm using a crate. We make a lower ventilation gap between the waterproofing and thermal insulation.

The bottom of the material for thermal insulation should be protected with a vapor barrier film. It is installed on the inner surface of the rafters using a conventional or construction stapler, everything must be overlapped and connected with adhesive tape.

Composite metal tile (with acrylic coating)

It is recommended to use a superdiffuse membrane as a material for waterproofing, but in this case only the upper ventilation gap is required. The bottom of the thermal insulation must be protected with a vapor barrier film.It can also be used for waterproofing films, while two ventilation gaps must be provided.

Natural roof tiles

We recommend using a diffuse and superdiffuse membrane as waterproofing, and you will need to make at least one, and preferably two ventilation gaps. You can also use a waterproofing film. For a vapor barrier, which will protect the bottom of the insulation, vapor barrier film. When using a waterproofing sheeting, two ventilation spaces are required, a lower and an upper.


When using asbestos-cement slabs, it is possible to use both diffuse and superadiffuse waterproofing membranes with a single ventilation gap from above between the roof and the membrane.

You can also use polypropylene or polyethylene waterproofing sheets, and then you will need to install two ventilation gaps, an upper and a lower one. Use vapor barrier tape to protect against steam.


The Euroslate has high thermal conductivity, therefore, even from the daily temperature difference, condensation may appear on the lower surface. For this reason, anti-condensation films and other waterproofing materials can be used as protection, and diffusion membranes are rarely used. Two ventilation gaps are required, and use a vapor barrier film as thermal protection against steam inside.

Seamed roof

It is recommended to use a vapor-tight and anti-condensation film with two ventilation gaps. It is also permissible to use waterproofing films (both perforated and non-perforated) made of polypropylene or polyethylene with two gaps. Diffusion membranes must not be used, only some special membranes for metal seam roofs.

Slate roofing

It is advised to use a diffusion and superdiffusion membrane, but with one (upper) ventilation gap. It is also permissible to use polypropylene or polyethylene waterproofing films and a vapor barrier film with two ventilation gaps.

In houses with a cold attic that is not heated, and in houses without heating, in general, it is not necessary to install a vapor barrier, there is also enough waterproofing. For this we recommend using a perforated film for waterproofing polypropylene or polyethylene.