Why is felt used under roof tiles

Can I insulate the roof myself?

Step 2: attaching the clamping felts

The clamping felt cut with allowance can now be clamped into the space between two rafters with slight pressure. The clamping allowance ensures that the insulation material is firmly in place and does not fall out. This process is repeated between all rafters until the roof space is completely lined. Leftovers, for example from the roll ends of the insulation material, can be put together without any problems.


It is important that every corner and every small space between the rafters is filled with insulation. This prevents thermal bridges.

Step 3: installing the airtight layer (vapor barrier)

So that the construction cannot be damaged later by penetrating moisture, it must be sealed with a vapor barrier. This special film is applied horizontally over the entire insulated area. It is attached to the rafter every 10 cm with a hand tacker. The vapor barrier should overlap approx. 10 cm at all connections as well as in the overlap area of ​​two sheets of film.


When connecting to adjacent components using sealant, think of a relief loop, because the roof is a movable component - the next storm is sure to come.

Step 4: sealing the vapor barrier film

Finally, the vapor barrier is sealed airtight at the overlapping points. For this purpose, a special one-sided adhesive tape is stuck to the entire overlap area of ​​the film webs. After the airtight layer has been completed, it must be mechanically secured using transverse battens.

Step 5: clad the roof walls

Before the roof walls can be wallpapered or painted, a suitable substrate and its "carrier" are required. For this purpose, counter battens (battens across the existing rafters) are attached over the vapor barrier film. This is required because the rafter spacing is too large and usually too uneven to attach interior cladding, e.g. plasterboard, directly to it. The desired inner lining can then be screwed to this battens. Then nothing stands in the way of the decorative design of the fully insulated attic space


It is particularly recommended that these lath gaps are also dammed with an under-rafter clamping felt. In this way, the efficiency of the between-rafter insulation can be improved by up to 30% in a simple way.

Image source: ISOVER