Alpine Automation’s twin-I beam composite joists have been successfully tested for 60min fire resistance at the Chiltern International Fire Ltd test centre.
The 12-3-3 configuration joists were constructed with 72x47mm TR26 graded timber for top and bottom chords, jointed with 1mm thick galvanised steel twin-I webs to give an overall depth of 304mm, and were spaced at 600mm centres.
The test was conducted with loads to simulate a floating floor construction using resilient battens, 18mm T&G chipboard flooring, 19mm plasterboard and 33kg/m2 sound deadening insulation with 15mm OSB base layer.
To help reduce airborne and impact noise, the two-layer plasterboard ceiling was supported by resilient bars at 400mm centres and a 100mm general purpose insulation was placed between the joists.
The structure complied with Part E sound regulations for separating floors, but alternative acoustic floating floor details can be used, provided they have similar noise reduction properties.
A 30min fire resistance test on 9-3-3 twin-I beams was also sucessful, exceeding the requirements of BS 476 Part 21 by more than 20%. The test was carried out with 18mm T&G chipboard flooring and 15mm standard plasterboard ceiling directly fixed to the 219mm deep joists.
Twin-I beams, which are suitable for traditional or timber frame construction, are fabricated by Alpine licensees.
