Gapotape – Perfect Insulation with PIR Board

Gapotape is a multi-award-winning, unique yet simple combination of foil and foam tape, specifically designed for use in conjunction with rigid insulation board. It is the first product proven by the BBA (British Board of Agrément) to eradicate air leakage and thermal bridging where rigid boards are fitted between rafters in roof, walls and floors.

Up until now, rigid insulation has been impossible to install between rafters, studs and joists without airgaps as even the most meticulous installations suffer from inevitable shrinkage, warping and movement of timber elements.

This means that the ‘as built’ U-value of rigid insulation is much less than its ‘as specified’ U-value. This ‘performance gap’ is one of the biggest issues in the construction sector and is a problem for almost all insulation types, most of which have no remedy.

Gapotape over EcoTherm PIR rigid board

BBA testing illustrates that with Gapotape, rigid insulation’s ‘as-built’ performance can be up to 5 times better as it will constantly expand to fill any space around the board. No other rigid product is capable of expanding on all sides in this manner making rigid insulation fitted with Gapotape truly unique in this application.

Gapotape offers the first holistic non-permeable insulation solution. For the consumer this will ultimately result in a more comfortable living environment, not to mention £1,000’s of fuel savings throughout the lifetime of the build.

Gapotape installation

When Gapotape is installed around the perimeter of PIR ridged insulation boards, with no air gaps and a tight fit on all four sides the correction level 0 for air voids can be used when calculating U-values to BS EN ISO 6946. Without Gapotape installed a correction for air voids level of 1 or 2 may need to be added to the U-value calculation giving a poorer result.

  British Board Agrément Assessment report – April 2015

🛒 Use discount code SB2020 at


Perfect Gapotape Partners

EcoTherm polyisocyanurate (PIR) rigid thermal insulation board

Kingspan Kooltherm K-range fibre-free rigid phenolic core

Part L amendments are on the way, so get ahead of the issue by eliminating the ‘as specified’ vs ‘as built’ performance gap for insulation.

🔗 Conservation of fuel and power Approved Document L

🔗 The Performance Gap at Wikipedia

Robin loves the Festool ISC 240 cordless insulating-material saw.

Buy the Festool ISC 240
  • Voltage: 18 V.
  • Stroke length: 26 mm.
  • Stroke rate: 3000 min-1.

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About Dylan Garton

Dylan Garton
Dylan Garton is a freelance video producer, camera operator, animator and editor. He also writes scripts, articles and develops websites. Cofounder of Skill Builder.

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