Open-cell, breathable & acoustic
Sucraseal is a lower-density, vapour-open open-cell foam. That makes it well suited to internal walls, ceilings and partitions where a breathable build-up and acoustic damping are wanted — a different role from the rigid, low-permeability, structural performance of closed-cell Nexseal LE. The two are specified for different jobs, not as direct substitutes.
Fire performance & AC377
Classified Class 1 to BS476 Part 7 when left uncoated, and Class A to ASTM E-84 (UL723) with a Flame Spread Index below 25 and Smoke Developed Index below 450 at 4". Sucraseal meets the ICC-ES AC377 Appendix X life-safety benchmark for foam in attics and crawlspaces without a separate ignition barrier or coating. A thermal barrier may still be required in habitable spaces under building regulations.
Vapour control & environment
Meets one perm or less for a Class III vapour retarder when installed at 50.8 mm, with a declared water vapour resistance factor of μ 8.8 (BS EN ISO 13788:2012); design to BS 5250:2021, AVCL where required. Low-VOC (CDPH 01350), rapidly renewable content 17% (ASTM D-6886), service range -40°C to 82°C. Self-bonds to the substrate as it cures.
