BIWA multifunctional tape 3C plus 30 mm beneath window sill, parapet junction

The BIWA Multifunction Tape 3C plus 30 mm is the narrow version of the pre-compressed multifunction tape made of impregnated flexible polyurethane foam – for the parapet connection under the window sill. Like the wide tape, it seals according to the principle “tighter inside than outside”: airtight on the room side to DIN 18542 BG R, driving-rain-tight and vapour-permeable on the outside to DIN 18542 BG 1. It comes in black, self-adhesive on one side, on the roll in four joint ranges from 4 to 30 mm.

Benefits at a glance

• Matching the 3C-plus system: same impregnation and same test classes as the multifunction tape in 55 to 84 mm width.
• Tight against driving rain: over 600 Pa to DIN 18542 BG 1, joint permeability coefficient a below 0.1 m³/[h·m·(daPa)ⁿ].
• Vapour-permeable to the outside: sd value below 0.5 m, moisture in the joint can dry out.
• Fire protection: flame-retardant, building material class B1 to DIN 4102-1.
• Quick to install: the self-adhesive side holds the tape on the component during installation.

Areas of application

• Parapet connection under the window sill during window installation
• Connection joints of 4 to 30 mm width, depending on the tape size
• New build and refurbishment, on the inside and outside of the joint

Limits & notes

The sealing effect depends on the degree of compression: once installed, the joint width must lie within the range of use of the chosen size. The tape cannot compensate for standing water or permanent water exposure – this applies especially under the window sill.

Application & tips

Free the joint flanks of dust, grease, old sealant and mortar residues. Allow 1 to 2 cm extra per metre, cut off the over-compressed start and end piece, peel off the cover of the self-adhesive film and stick the tape, slightly compressed and not stretched, onto the clean, dry component – at least 2 mm behind the front edge of the joint. In cold conditions store it at about 20 °C for 24 hours beforehand; a hot air gun speeds up the expansion. Store dry and in the original packaging below 20 °C, shelf life 1 year.

Frequently asked questions

Which size do I need?
The number after the slash is the joint range in mm. The measured joint width must lie within this range.

How long is a roll?
8 m for 4–9 and 7–15 mm, 6 m for 10–20 mm, 4 m for 15–30 mm.

Which side faces inwards?
The side marked “inside” always faces the room side.