Suspended ground floor - Timber Joists

Thermal insulation

Rockwool Flexi insulation is laid between the joists and supported by plastic netting or a proprietary support membrane. The top of the insulation should be fitted as close as possible to the underside of the timber flooring deck to avoid any air gaps.

Underfloor ventilation

Approved Document  Section 4 requires the provision of through ventilation to external air under suspended timber ground floors. The ventilated air space must measure at least 75mm from the ground covering to the underside of any wallplates and at least 150 mm to the underside of the suspended timber floor or insulation (whichever is the lower).