Rockwool floor type 3.1A guidance specification to meet ADE Section 3 Airborne: Rw 54 dB (Rw 66 - 12 Ctr)
Impact: Lnw 54 dB
Test Report ref. L03 272 & 273
. 18 mm t&g flooring grade chipboard on . 15 mm plasterboard (density 13Kg/m2) . 50 mm Rockwool Rockfloor resilient layer on . 15 mm OSB on . 200 × 50 mm timber joists @ 400 mm ctrs . 100 mm Rockwool Flexi between joists . Resiliant bars fixed at right angles to joists @ 400 mm ctrs. . Ceiling finish, 2 layers of 15 mm plasterboard (density 13Kg/m2 per board) (26 Kg/m2) . Pre-completion site testing is required
Fire A fire test using 100mm Rockwool Flexi between timber joists achieved a one hour fire resistant floor.
We also have improved the system by; a) reducing the joist size to 195 x 46mm (a typical modern timber size), b) increasing the imposed stress to the maximum stated in Building Regulations for this type of floor for use as bedrooms and living rooms; and c) reducing the thickness of the plasterboard ceiling from 12.5mm to 9.5mm .
There are a number of benefits for using this system in preference to double boarding the soffit with fire resisting plasterboard; 1) Reduced weight on the joist structure 2) The ceiling can remain undisturbed, thus protecting any decoration, such as an artexed pattern, and coving already in place 3) The Flexi between the joists will also help to reduce airborne sound.
The assessment also includes the provision for lathe and plaster ceilings as well as plasterboard; square edged and T&G floor boards as well as T&G chipboard. It also includes a method for installing the Flexi insulation from below.
