Roof
roof pitch
Drempel
Flat roof
Upper floor slab
Solid ceiling
timber-beamed ceiling
Nail binder
Attic conversion
External wall
Façade
Partition joint in a house
cellar wall
Ground floor
cellar ceiling
Stairway to the cellar
Solid ceiling
Cap ceiling
Timber joist floor/cavity
Special components
When carrying out external refurbishment, the existing insulation between the rafters can remain in place if it is still effective. By adding new insulation on top of the rafters from the outside, an insulation standard eligible for financial support can be achieved without any problems. The load-bearing structure is protected against cold and damp. No thermal bridges are created.
In the case of old roofs, the airtightness required by the Building Energy Act (GEG) is generally not achieved, even if the loft has already been converted. During renovation, a membrane is laid beneath the above-rafter insulation, which acts both as an airtight layer and a vapour barrier. Permanent airtight connections at the eaves and roof edge are particularly important for the roof to function properly.
Important: The installation must be airtight, particularly where it joins adjacent building elements, chimneys, roof windows, etc.
The required insulation thickness depends on whether there is already insulation in the cavity, as well as on the type of insulation material used for the above-rafter insulation. For most types of insulation material, a layer of at least 10 cm is recommended. In the case of above-rafter insulation using polyurethane panels, in combination with between-rafter insulation, insulation thicknesses of 8 cm are often sufficient to achieve U-values of ≤ 0.14 W/(m²·K) and thus meet the renovation requirements under the GEG, BEG EM or the ESanMV (Energy Renovation Measures Ordinance).
All the benefits at a glance:
- Existing installations remain unchanged. The interior of the house is hardly affected by construction noise and dirt during the roof renovation.
- There is no need to double up the rafters, as would be required for a renovation using only between-rafter insulation.
- On-rafter insulation serves as a replacement for the usual solid timber cladding, acts as a roof underlay (for enhanced protection against rainwater) and improves thermal insulation.
- The load-bearing timber structure is located in the warm zone and is therefore protected from condensation and moisture penetration.
- Where structural reserves are limited, lightweight insulation boards, e.g. made of polyurethane, are advantageous
- CO₂ emissions are reduced
- Energy costs can be significantly reduced
- Draughts and mould disappear. Furthermore, comfort in winter is enhanced due to higher temperatures on the inside of the roof slopes. Summer heat protection is also significantly improved.
Funding:
All costs associated with this measure are eligible for tax relief at 20 per cent or, under the BEG (Federal Funding Scheme for Energy-Efficient Buildings), for a grant of up to 20 per cent (as part of an individual refurbishment roadmap, iSFP) of the total costs in the form of an investment grant.
The BEG funding scheme is administered by the Federal Office for Economic Affairs and Export Control (BAFA). Some towns or local authorities offer additional funding. You can obtain assistance with funding applications from qualified energy efficiency experts.
Can I install insulation myself?
No. You can, however, carry out supporting tasks. Please contact a specialist contractor for this.