How Many Loft Stilts Do I Need? A Simple Guide to Calculating Quantities
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One of the most common questions we receive at The DIYer is: "How many loft stilts do I actually need?" Order too few and you will be waiting for a second delivery. Order too many and you have wasted money. This guide gives you a simple, reliable formula for calculating the right quantities for any loft.
The Simple Formula
For standard UK joists spaced at 400mm centres, you need approximately 9 to 10 loft stilts per square metre. For joists at 600mm centres, you need approximately 6 to 7 stilts per square metre.
| Loft Area | Stilts (400mm spacing) | Stilts (600mm spacing) | Recommended Pack |
|---|---|---|---|
| 4 m² | 36–40 | 24–28 | Box of 64 |
| 7 m² | 63–70 | 42–49 | Box of 96 |
| 10 m² | 90–100 | 60–70 | Box of 128 |
| 15 m² | 135–150 | 90–105 | Box of 256 |
| 20 m² | 180–200 | 120–140 | Box of 256 |
Step 1: Measure Your Loft Area
Measure the length and width of the area you want to board and multiply them together to get square metres. For irregular shapes, divide into rectangles and add them up.
Step 2: Check Your Joist Spacing
Measure the distance between the centre of one joist and the centre of the next. Most UK homes built before 1990 have joists at 400mm centres. Homes built after 1990 often have joists at 600mm centres.
How Many OSB Boards Do You Need?
Each OSB loft board measures 1220mm x 300mm, covering approximately 0.366 m² per board. A pack of 18 boards covers approximately 6.5 m². Always add 10–15% for cuts and waste.
| Loft Area | Boards Needed | Recommended Pack |
|---|---|---|
| 4 m² | 11 boards | Pack of 12 |
| 7 m² | 20 boards | Pack of 18 + Pack of 6 |
| 10 m² | 28 boards | Pack of 18 + Pack of 12 |
| 15 m² | 41 boards | 3 x Pack of 18 |
How Many Screws Do You Need?
Allow for approximately 2 screws per stilt fixing point. Our 4.0 x 30mm screws are available in packs of 200, 400, and 1000 — for most loft projects, a pack of 200 or 400 is sufficient.
Still Not Sure? We Will Calculate It For You
Send us your loft dimensions and we will tell you exactly what to order. Email us at info@thediyer.co.uk or call 07555 429129.
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