Advanced options
Boarding directly onto joists squashes 270mm insulation to 100mm and roughly halves its effect: loft legs (or a timber counter-batten frame) lift the deck above it. Board a walkway and a storage zone, not the whole loft; keep clear of downlight housings and don't block eaves ventilation.
What The Loft Boarding Calculator Works Out
- Boards needed: the area divided by the 1220 x 325mm chipboard loft panel (0.4 m2 each) plus 5% for cuts, rounded up and sold in packs of three. The panel standardised at that size because it posts through a standard loft hatch; 10 m2 takes 27 boards, so 9 packs.
- Loft legs and screws: four plastic loft legs per board when raising the deck, each with four screws, or six screws per board when fixing straight to joists. Boarding directly onto 270mm of quilt insulation compresses it to joist depth and roughly halves its value, so legs (or a timber frame) are the standard answer.
- Materials cost: packs at your price plus legs at about GBP 1.20 each. Board a walkway from the hatch plus a storage platform of a few square metres, not the whole loft, and keep books and tiles downstairs: ceiling joists are sized to hold the ceiling, not a library.
- Cutting waste (advanced): edit the 5%: awkward lofts with lots of trimming around trusses and downlight housings justify 10%.
- Leg price and legs per board (advanced): loft legs run GBP 1 to GBP 1.50 each in bulk; some systems use three per board on narrow joist spacings, and taller 300mm legs cost more.
- Screw boxes (advanced): the screw count rounded up to boxes of 200 at your price, and the full materials total including them.
- DIY cost per m2 (advanced): the complete materials bill divided by the area, typically GBP 25 to GBP 35 per m2 raised on legs.
- Professional installation (advanced): supply-and-fit quotes commonly run GBP 45 to GBP 70 per m2 for raised boarding, often with a minimum charge; the card shows the premium over doing it yourself.
- Timber frame alternative (advanced): the traditional counter-batten approach, about 2.75 m of 47 x 50mm timber per m2 at 400mm centres, costed at your price per metre. It is stiffer than legs but adds weight and needs cross-battening to clear deep insulation. Stop short of the eaves to keep the airflow that dries the roof timbers, and leave cables visible rather than buried under the deck.