Airtightness – Got it Taped

NBT’s range of Siga airtightness tapes and membranes offers a simple way of achieving remarkable levels of building airtightness, using products that are completely free from toxins, solvents, plasticisers and formaldehyde. The tapes and adhesives have incredibly high adhesive strength and will maintain their peak performance for over 60 years; showing no signs of ageing.

Designed for every specific cause of air leakage through the building envelope, NBT Siga tapes and membranes include highly flexible tapes for sealing circular pipework or ductwork penetrations; specialist tapes to seal adjoining sheets of vapour barrier and adhesive paste to seal the vapour barrier to masonry gable walls; pre-folded tapes that fit neatly into corners to seal window and door frames; and tapes to seal the joints between abutting OSB boards or woodfibre insulation boards.

The tapes and adhesives are designed to allow for building movement, without compromising their performance.

Achieving airtightness is crucial in optimising the thermal performance of the building envelope; it has been shown that a 1mm wide by 1m long gap in the building fabric will reduce the thermal insulation level by 35-65% (depending on wind strength).

Too many buildings whose theoretical airtightenss is predicted to be very high are simply not achieving it in practice. Often this comes down to the fact that on-site workmanship just doesn’t accommodate the levels of accuracy and care required to deliver the airtightness for top level energy performance, such as that required for Passivhaus, the AECB silver and gold standards, and the higher levels of the Code for Sustainable Homes.

In addition, junctions, doorways and window openings, and penetrations (pipework, ducting, wiring) through the building fabric mean that it is virtually impossible to achieve optimum airtightness without the use of purpose-designed tapes.

To ensure windtightness and thereby prevent cold outside air form cooling a building’s insulation, thereby reducing its effectiveness, NBT’s Siga range includes Wigluv, the only tape on the market for external application that is permeable to internal moisture and at the same time waterproof. The moisture from inside the building can diffuse, but outside dampness cannot penetrate.