ISO-Chemie’s high performance expanding foam sealing tape has been specified for an innovative low carbon technology college in Bath.


The ISO-BLOCO ONE tape has been specified to provide a high performance airtight, acoustic and thermal interior and exterior seal between the ModCell® straw-filled, cassette-style prefabricated panels used in the construction of the new two storey 1,200 sq m Nucleus building teaching block at the Hayesfield Girls’ School.
The Nucleus building incorporates a layout of labs and classrooms arranged around a super lab and double-height learning resource centre to allow the school to extend its provision of science teaching.

Sustainability was a key driver of the project, which demonstrates the benefits of the straw bale cladding system to eliminate the need for a separate structural frame and increase the speed of build on site through off-site pre-fabrication methods. ModCell® has been used to build the super-insulated structure to the highest ecological standards using thermally efficient, 48cm thick, prefabricated straw bale wall panels. These utilise the excellent thermal insulation qualities of straw bale and hemp based prefabricated panels to allow super-insulated, high-performance, low energy ‘passive’ buildings to be constructed using renewable, locally sourced, carbon sequestering materials.


The ISO-BLOCO ONE tape has been used to fill the 10mm expansion joints between the ModCell® panels. This will significantly help to achieve an excellent target of <2.0 m³/hour/m² measured at 50 Pascals air tight seal for the complete building – a good standard for the construction industry is anything between 3 – 5 m³/hour/m². Finlay White, business development director at Bristol-based ModCell®, said: “ISO-BLOCO ONE is an excellent product, meeting the requirements for an easy-to-install, cost effective and very reliable all round sealing solution.” Peter Thompson, ISO-Chemie’s UK general manager, said: “Systems like ModCell® are increasingly being specified as low cost, practical and very sustainable building products for ground breaking projects like the one at the Hayesfield Girls’ School. So for us to be involved in this ground breaking initiative not only reinforces our strong environmental credentials but is also a strong endorsement for the airtight, acoustic and thermal benefits provided by our foam tape solutions.”

ISO-BLOCO ONE offers a single product ‘fit and forget’ solution for fast and effective sealing based around the European RAL principles of three level sealing - the inside seal area is more airtight than the external one, allowing any trapped moisture inside the joint, or within the wall, to escape outwards rather than into the building. The external seal area provides weather resistance and breathability with a minimum resistance of 1000 Pascals (hurricane forces), while the intermediate seal area provides extra thermal and acoustic properties, with a U-value between 0.55 and 0.8 subject to tape size, and the internal one air tightness and humidity regulation, the tape installation itself gives less than 0.01 m³ air loss when tested at 1,000 Pascals air pressure difference. All three levels are designed to accommodate movement between the adjacent materials.

Once installed, ISO-BLOCO ONE ensures a building is better protected from elemental factors like wind, dust and moisture ingress by accommodating the changes in structural movement caused by environmental, cyclical and settlement factors.
Product has CE marking and complies with energy saving regulations (EnEV) on windows and doors as well as the RAL quality assurance association, has an EC1 rating for very low emissions and a B1 fire resistant rating. It is able to accommodate extremes of temperature changes – from -30°C to + 80°C and is available with a 10 year performance warranty.

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