An expanding foam tape will provide a high-performance, airtight, acoustic and thermal seal between straw-filled, cassette-style building blocks.

ISO-Chemie’s expanding foam tape (ISO-BLOCO One) has been specified for a major research project at the University of Bath that will investigate the feasibility of constructing buildings from straw bales. ISO-BLOCO One will provide a high-performance, airtight, acoustic and thermal seal between the straw-filled, cassette-style building blocks used to construct the two-story BaleHaus at Bath.

The BaleHaus is a research building constructed using the ModCell® system in order to assess the use of straw as an efficient, effective and long-term building material. The system uses the excellent thermal insulation qualities of straw bale and hemp construction to form prefabricated panels. These panels allow super-insulated, high-performance and low-energy “passive” buildings to be constructed with renewable, locally sourced, carbon-sequestering materials. These buildings are constructed to meet the demanding PassivHaus specification with resultant zero heat requirements, which will save money and CO2 emissions.

Project Details

Strips of ISO-BLOCO One have been installed in the 10-mm expansion joints between the 3 m² bale blocks to form a 0.86 m³/hour/m² measured at 50 pascals airtight seal. (The construction industry norm ranges from 3-5 m³/hour/m².) ModCell, which has a number of other research buildings around the UK, is three years into an extensive four-year development program supported by funding from dBERR (formerly the DTi), Carbon Connections and the Technology Strategy Board. The program has already confirmed that ModCell and buildings like the BaleHaus can meet and exceed the standards required in mainstream construction.

“ISO-BLOCO One is an excellent product; it meets the requirements for an easy-to-install, cost-effective and very reliable all-around sealing solution,” said Finlay White, Marketing and Operations director for ModCell.

According to Peter Thompson, ISO Chemie’s UK general manager, “Increasingly, systems like ModCell are considered to be low-cost, practical and very sustainable building products for construction projects. So, for us to be involved is a major coup and an endorsement of the high-performance and multi-purpose solution offered by ISO-BLOCO One.”

Multiple Benefits

ISO-BLOCO One offers a single-product, fit-and-forget solution for fast and effective sealing. It is based on the European RAL principles of three-level sealing, where the inside seal area is more airtight than the external one; this enables any trapped moisture inside the joint or within the wall to escape outward rather than into the building. The external seal area provides weather resistance and breathability, while the intermediate seal area gives extra thermal and acoustic properties and the internal seal maintains air tightness and humidity regulation. All three levels are designed to accommodate movement between the adjacent materials.

Quick and easy to apply, the self-adhesive ISO-BLOCO One provides a high-performance seal for window and door joints up to 30 mm wide, and it is impermeable to driving rain at a minimum of 1000 Pa, a 66% improvement in reliability over most conventional joint-sealing tapes. The internal airtight seal has been tested at 1000 Pa pressure difference (20 times higher than UK building regulations), and it was found to give less than 0.1 m³ of air loss. At the same time, depending on the tape width, it can also supply a U-value of 0.55 and reduce sound by 45 dB.

Once installed, ISO-BLOCO One ensures that a building is better protected from elemental difficulties such as wind, dust and moisture ingress by accommodating the changes in structural movement caused by environmental, cyclical, and settlement factors. The product complies with energy-saving regulations (EnEV) on windows and doors, as well as the RAL quality assurance association, and is able to accommodate extreme temperature changes from -30°C to over 80°C.

About ISO-Chemie

ISO-Chemie is one of Europe’s main producers of impregnated foam sealants, specializing in the manufacture of foam products from polyethylene (EPE), polypropylene (EPP) and polyurethane (PUR). The company’s UK technical and distribution operation is based in northeast England and is supported by a dedicated logistics service.

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