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
Basement access points usually consist of wooden frames with fitted wooden doors and are not insulated. There are gaps between the wooden planks and between the treads and risers, through which warm air can enter the cellar entrance and cold air can enter the living area. Thermal insulation is virtually non-existent. Heat loss is enormous.
Draughts enter the living area through gaps and missing seals, which exacerbate heat loss and impair living comfort.
To reduce heat loss and improve living comfort, the stairwell leading to the cellar should be effectively insulated. :
Firstly, the condition of the stairwell should be checked and any damage or leaks repaired. The insulation materials are then installed on the ‘cold side’ of the stairwell (i.e. inside the stairwell itself). Insulation boards made of phenolic resin (WLS 021) or polyurethane (PU) (WLS 023) are suitable for this purpose and can be either glued or screwed into place.
Alternatively, PU spray insulation can be applied.
The wooden stair treads should also be insulated. Care must be taken to ensure the installation is as airtight as possible.
In the next step, the insulation is covered with suitable materials, such as plasterboard or gypsum board. This protects the insulation from damage and ensures a neat finish.
Plasterboard or gypsum fibre boards can also be installed beneath the stair treads, and the resulting cavities can then be blown out with fibre insulation or filled seamlessly with mat or loose-fill insulation.
In addition, the doors at the bottom of the stairs should be checked for airtightness. If necessary, new seals can be fitted to prevent cold air from entering. Wooden doors should also be fitted with insulation boards on the cold side.
The insulation boards should be as thick as possible. It is essential to ensure an airtight installation. This can be achieved using adhesive tape and suitable sealing materials such as acrylic or silicone sealant. As space is limited, very high-quality and highly insulating materials such as polyurethane (aluminium-laminated) WLS 023 or phenolic resin WLS 021 should be used.
With blow-in insulation, the thickness depends on the resulting cavity.
All the benefits at a glance
Lower heating costs: Heating costs can be reduced by up to 5 per cent.
Further benefits:
- Energy savings
- Improved living comfort and a pleasant room temperature in the cellar
- Protection against damp and improved indoor air quality
- Extended service life of the building structure
- Environmentally friendly and helps maintain the building’s value
- Prevention of draughts and thermal bridges.
Funding: unfortunately, this measure is not eligible for funding as a stand-alone measure, but it does improve overall performance as part of a KfW renovation (to the KfW-x standard)
Can I install the insulation myself? Yes. Insulation boards can be installed by yourself. You can also fill the cavity between plasterboard panels and stair treads yourself. However, blowing in fibre insulation into this cavity can only be carried out by a specialist blow-in insulation contractor. You can fit the plasterboard yourself, but you will need a specialist contractor for the blow-in insulation.
For PU spray insulation, a specialist contractor such as Pluimers or Grozema is required.
Insulation materials: Board insulation: Phenolic resin WLS 021, polyurethane WLS 023 (aluminium-laminated),
Blow-in insulation materials: mineral wool, hemp,
Blown-in insulation materials: cellulose, glass
wool, PU spray foam
