Laying the vapor barrier: where does the vapor barrier have to go?

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Vapor barrier and vapor barrier are important elements when building or expanding rooms. You can find out how far they are to be relocated here.

Vapor barrier or vapor barrier?

Although the terms are often used interchangeably, they are different materials. A vapor barrier is used when the sd value is between 0.6 and 1,500 meters. The vapor barrier is used from 1,500 meters.

The sd value stands for "water vapor diffusion equivalent air layer thickness" and indicates the resistance the material has to water vapor.
Before laying, it must be clear what value is given in order to make the right decision.

function

Whether it is a barrier or a brake: it is a material that prevents water vapor or humidity from penetrating into the insulation of the walls. It should therefore be installed in every room that is exposed to increased humidity. This includes:

  • bath
  • roof
  • kitchen
  • Laundry room

Rooms with lots of leafy plants, indoor fountains or aquariums can also be part of it.
The roof should be equipped with it, as warm and thus potentially more humid air rises and spreads there in the building fabric. The possible consequences of this are:

  • Building materials get rotten
  • Putrefaction
  • Mould

On the one hand, this can lead to the creation of substances that are hazardous to health and spread through the air in the room. On the other hand, the building fabric suffers. This can generate high costs and also entail immense effort.

Possible materials

Various materials can be used for the locks and brakes. These include, for example:

  • aluminum
  • Plastics such as polyethylene or PVC
  • OSB3 and OSB4
  • paper

Often these are foils, but in the case of aluminum and OSB, panels can also be used. Both variants have advantages and disadvantages.

Loft conversion

foil

The advantages of the vapor barriers in film form are:

  • easy cropping
  • lower weight
  • easier attachment

Another advantage is that the film can be attached more flexibly. In the case of difficult sloping ceilings, bay windows or other structural features, this makes work easier and can significantly reduce the effort. The disadvantage, however, is that foils can be damaged more quickly than plates and may therefore need to be replaced more frequently

have to.

Note: The seams are also comparatively easy to close. In addition, the structure is space-saving and thus reduces the space taken up.

plates

Fixed panels have the following advantages:

  • provides a good base for the cladding to be attached
  • durable
  • stable

On the other hand, they are heavier in weight and less flexible when it comes to attaching them. Trimming is also more difficult.

Note: Slabs can only be laid by two people. So organize at least one helper for this task.

Laying foil

In order to create an effective barrier against steam and humidity, a few factors must be taken into account when installing. First of all, however, the right utensils are required. These are:

  • Scribing pen
  • Craft knife
  • foil
  • staple gun if necessary
  • duct tape
  • Glue
  • Measuring tools such as folding rule and scaled angle
  • spatula

Once the equipment is ready, the following steps are required:

Roof extension, vapor barrier and insulation

1. cleaning

The surface is swept before laying. It should be smooth and swept clean.

2. Lay out the foil

The film is rolled out so that it extends from one rafter to the next and protrudes from both the walls and the rafters.

3. Measure and cut

The vapor barrier should protrude at least two centimeters from walls. There must be ten centimeters on the rafters. Also take into account any necessary cut-outs, such as for load-bearing beams.

4. Laying out

After cutting, the film is laid out and aligned again. In addition, it should be smoothed out well with the spatula

will.

5. Attach

You can staple the vapor barriers to the rafters at regular intervals. On the other hand, they are glued to walls and other vertical surfaces. To do this, fold two centimeters of the edge upwards as a fold. The adhesive is applied between the wall and the film and smoothed out with a spatula. There should be no air bubbles underneath.

Tip: Select the adhesive and tape that match the film. In some cases complete systems are found. These make the selection easier.

Seams

The seams of the vapor barrier must overlap ten centimeters. In addition, they must also be glued together. However, only adhesive tape is required for this. Make sure that the edges are sealed tightly and evenly.

Lay the panels

If you are laying slabs, the process is similar. After measuring, cut these accordingly. In contrast to the foil, however, a saw and not a cutter knife is required for this. They can also be screwed to the rafters to provide more stability.

Roof insulation in cross section - vapor barrier

Put

In the case of panels as a vapor barrier, it is of course not possible for the individual elements to overlap. Otherwise there would be bumps. You must therefore be aligned so that the resulting joints are as small as possible.

It is also necessary to glue the joints between the panels and the distances to the walls. Otherwise, water vapor could still penetrate the insulation. Parquet floor adhesives and assembly adhesives are suitable for this.

Tip: A cartridge gun helps to pour the glue into narrower joints. It also helps if the side edges are already provided with glue before aligning and after screwing.

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