What size are standard loft boards?

Standard loft boards in the UK are 2400 × 600 × 18mm chipboard panels, giving a coverage of 1.44 m² per board. They are tongue-and-groove for a secure fit. Smaller boards (1220 × 320mm) are available for tighter access through small loft hatches but are less efficient for large areas.

Do I need to raise loft boards above insulation?

Yes. You should never compress loft insulation by laying boards directly on top of it. Compressed insulation loses its thermal performance and can cause condensation problems. Use loft legs (adjustable stilts), timber battens on top of the joists, or purpose-made loft boarding kits to raise the boards at least 170mm above the joists, allowing full-depth insulation underneath.

How much wastage should I allow for loft boarding?

Allow 10% wastage for loft boarding. Lofts are rarely perfectly rectangular — you will need to cut boards around pipework, cables, water tanks, and irregular edges. The tongue-and-groove joints also mean some material is lost at the perimeter. If your loft has many obstructions, consider allowing 15%.

What screws should I use for loft boards?

Use 4 × 30mm or 4 × 40mm coarse-thread chipboard screws (sometimes called drywall screws). You need approximately 8 screws per standard board — two at each short end and two at intermediate joist positions. Pre-drilling is recommended to prevent the chipboard from splitting near edges.

Can I board my loft myself?

Yes, loft boarding is a popular DIY project. The main considerations are: ensuring you walk only on joists (not between them), raising boards above insulation, leaving ventilation gaps at the eaves, avoiding compressing or displacing insulation, and not overloading the ceiling joists. Check joist capacity before storing heavy items — most ceiling joists are only rated for 0.25 kN/m² (about 25 kg per m²).

Loft Boarding Calculator — How Many Loft Boards Do I Need?

Calculate the number of loft boards, battens and screws needed for your loft storage floor. Includes 10% wastage and UK standard board sizes.

Loft Length

Internal length of loft area to board

Loft Width

Internal width of loft area to board

Board Size

Standard 2400 × 600mm is most common and efficient

Joist Spacing

Measure centre-to-centre between joists

Include battens (to raise above insulation)

75 × 50mm timber battens at each joist position

Include screws

8 screws per board, boxes of 200

Price Per Board (optional)

Enter price per board for a cost estimate

How We Calculate This

This calculator determines the number of loft boards needed by dividing the total loft area (including a 10% wastage allowance) by the coverage area of each board.

The formula

Boards = (Loft length × Loft width × 1.10) ÷ Board area

Board sizes

Standard board: 2400 × 600 × 18mm = 1.44 m² coverage
Small board: 1220 × 320 × 18mm = 0.39 m² coverage

Battens

Battens (75 × 50mm / 3" × 2" timber) are needed to raise the boarding above the insulation. One batten runs across the loft width at each joist position. The number of joist positions depends on your joist spacing (400mm or 600mm centres). Battens are supplied in 2.4m lengths.

Screws

Eight screws per standard board is the recommended fixing rate — two at each short end and two at each intermediate joist crossing. This gives a secure fix without over-fixing. Use 4 × 30mm coarse-thread chipboard screws.

Important notes

Always raise boards above insulation using battens or loft legs. The current UK recommendation is 270mm of loft insulation (Approved Document L), so boards should sit at least 270mm above the ceiling. Maintain ventilation gaps at the eaves — do not push boards right to the eaves edge.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.