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Sisalkraft Building Papers - Sisalkraft 420

Insulation Products: Insulation Products for Floors > Accessories for Flooring Insulation Products

Product Code: 62012

BSK Building Papers 2
BSK Selection Table

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Sisalkraft 420.pdf

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Sisalkraft 420.pdf

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Product Description:

Product Description:

Sisalkraft 420 Vapour Check has a Waterproof underlay / separation layer & vapour check
Condensation resistant non slip surface
Accreditation : BS 1521 A1F

Sisalkraft 420 is a waterproof Building paper meeting the requirements of BS 1521 A1F. It is used as a waterproofing/weatherproofing layer in Building construction as a vapour check membrane and for temporary protection and separation where a tough water resistant material is needed.


Sisalkraft 420 is a traditional waterproof building paper with two piles of wet-strength pure kraft paper laminated together with bitumen reinforced with glass fibre yarn.

Technical Data

Basis Weight g/m2


Tensile Strength
-along roll
19.0 kN/m

-across roll
9.0 kN/m


3.0 g/m2/d

Vapour Resistance

68 MNs/g


Store rolls before use on end on a clean dry surface protected from the weather. Material should not be unrolled if the temperature is below 5°C as the adhesive will become brittle and may crack. Depending on application Sisalkraft 420 is laid over flat surfaces or fixed to studwork formwork or similar. It may be stapled nailed or fixed with self-adhesive tapes.

Sisalkraft 420 can be folded and cut easily using a knife or scissors. The bitumen adhesive will tend to seal around nails or other fixings to maintain a water and water vapour tight construction. Edges should be overlapped by at least 100mm and if the installation is intended to be waterproof or water vapour-tight the seams should be welted or taped using a durable self-adhesive polymer tape.

Sisalkraft 420 is not intended as a primary weatherproofing layer and should be covered by other materials if wet or windy weather is expected.


Standard Roll Size
1000mm x 25m
1000mm x 50m
1250mm x 50m
1500mm x 50m

Roll Weight
7.6 kg
15.1 kg
19 kg
23 kg

All information given in good faith and is believed to be accurate. Technical data is based on laboratory testing and represents average values. Specific lots may vary above or below these values.

Click on the Sub Code for more details.

Sub Code
25000 mm
1000 mm
25m x 1000mm Roll
50000 mm
1000 mm
50m x 1000mm Roll
50000 mm
1500 mm
50m x 1500mm Roll

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