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.

Construction

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)		313g
Tensile Strength	-along roll	19.0 kN/m
	-across roll	9.0 kN/m
MVTR		3.0 g/m2/d
Vapour Resistance		68 MNs/g

Fixing/Sitework

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.

Availability

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.