Kerabit 4000 Base

Kerabit 4000 Base is a  torch-on underlay membrane in multi-layer membrane system. This product is used for the waterproofing and radon insulation of foundation walls.

The carrier consists of polyester. The underside of the product is coated with torch-on bitumen and the top side with sand granules.

We have improved the Kerabit 4000 Base underlay membrane

The thinner and more easily melting protective plastic film and the grooves on the bottom surface allow for a faster and more secure installation.

The protective plastic film is only partially attached to the torch-on bitumen, thanks to the grooves. Therefore, it melts faster and more reliably than traditional plastic films fully connected to the bitumen, reducing the heat and gas required in the installation. The product’s adhesive properties have also been improved.


Manufacturer / Manufactured for Kerabit Oy, Lohja plant
Country of origin Finland
Conformity marking CE mark
Reaction to fire Manufacturer’s fire testing certificate
Fire Classification


Manufacturer’s declaration of conformity Kerabit modified bitumen roofing materials
Quality control Quality control agreement between the Plant and Eurofins Expert Services Oy
Nominal thickness approx. 3,5 mm
Nominal weight 4000 g/m²
Weight of the supportive layer 170 g/m² (+/- 10 g/m²)
Supportive layer Polyester
Rolls size 1 x 10 m / 10 m²
Packages / pallet 24 rolls
Weight / package 40 kg
Weight / pallet 985 kg

Handling and storage 
Modified bitumen membranes are to be stored on pallets in a dry and cool place. Use a plastic hood or tarpaulin for protection. When the outdoor temperature exceeds +40°C, the rolls must be protected from sunlight.


This product is used as an underlay and intermediate membrane of multi-layer membrane system and as a tanking membrane. This product is also highly suited for the radon insulation of basements. The interior and exterior surfaces of basement walls made of lightweight aggregate concrete blocks are sealed throughout, from the top down to the footing, by applying thin-coat plaster and by welding a Kerabit 4000 Base modified bitumen membrane onto the exterior.