Pitched  ventilated roofs– between and over ceiling joist
 
Part L: 2006 edition requires new pitched roofs with loft spaces to achieve a U value between 0.11- 0.16W/m2K. To meet this thermal performance and minimise heat loss through the timbers, Rockwool Roll should be cross-layered between and over the ceiling joists.
 
The first layer (generally of 100 mm thickness) is rolled between the ceiling joists, which are normally spaced at 400 mm or 600 mm centres. The insulation should be tightly fitted between the joists without leaving any air pockets. All material joints must be tightly butted.
 
A second layer of Rockwool Roll (e.g. 170 mm thick) is then cross-layered to cover the first layer of insulation and the ceiling joists. All material joints must be tightly butted.

If upgrading loft insulation, check to see if existing insulation between joists is tightly butt jointed to sides of timber. If not, remove and replace as above. If the existing insulation is in good condition, cross-layer this with a minimum of 150 mm Rockwool Roll.
 
Where possible, all cables should be lifted free of the insulation. If that is not possible The IEE Wiring Regulations, 16th edition, British Standard BS 7671: 1992 and the electricians’ Handbook (latest edition) give guidance on the correction factors to be applied in down-rating cables according to situation, and each case should be separately calculated.

Loft hatches

To preserve continuity of insulation, covers to loft hatches should be insulated with a minimum 100 mm thickness of Rockwool Roll. Double sided adhesive tape may be used to hold the insulation in place.

Dimensions
Rockwool Roll is supplied in a 1200mm width and preforated to allow the user to cut & twist the product for either 2x600mm or 3x400mm widths.

Rockwool Rollbatt is supplied precut in  either 2x600mm or 3x400mm widths.