How to screw down floorboards without missing the joist
Updated: 21 October 2026
The board moves when you step beside the doorway, or the nails you inherited are already proud. How to screw down floorboards is the order of work: find the joist, see what else is in the void, pilot where the timber is dense, then drive a headed screw until the head is flush. The boxes are the [floorboard screws comparison](/hub/flooring/floorboard-screws). If you buy through our links, we may earn a commission at no extra cost to you. We used UK fixing notes and the cable guidance NICEIC publishes for BS 7671.
The board moves when you step beside the doorway, or the nails you inherited are already proud.
The board moves when you step beside the doorway, or the nails you inherited are already proud. How to screw down floorboards is the order of work: find the joist, see what else is in the void, pilot where the timber is dense, then drive a headed screw until the head is flush. The boxes are the floorboard screws comparison. If you buy through our links, we may earn a commission at no extra cost to you. We used UK fixing notes and the cable guidance NICEIC publishes for BS 7671.
Our top picks
| Badge | Product | Thread | Drive | Size | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  fischer fischer Power-Fast II chipboard screws, 4.0 x 40 mm | Full | Phillips | 4.0 x 40 mm | 5.7 | about £19.85 | View offer |
 Ulti-Mate Ulti-Mate floorboard screws, 4.2 x 50 mm | Partial | Phillips and square | 4.2 x 50 mm | 8.6 | about £9.99 | View offer | |
| Alternative |  Ulti-Mate Ulti-Mate tongue-and-groove screws, 3.5 x 45 mm | Partial | Torx (T10) | 3.5 x 45 mm | 5.9 | about £8.99 | View offer |
On this page
Find the joist and the void
A screw fixes a board only when it enters a joist. Between the joists it spins in air and it can meet a cable or a pipe. On an existing softwood floor the nail heads are the map, often 400 mm or 600 mm apart. A magnet, a stud finder, or filler over old nails can confirm the line. Mark the centre on the board you are keeping, not in the gap. If you cannot see the void, lift one board and mark pipes and cables on the board you will put back. A cable through a joist should be at least 50 mm from the top or the bottom, or mechanically protected, which is how NICEIC explains BS 7671. If you smell gas, strike metal, or see water, you stop. A snap-off kit under carpet has no view of that void, and it stays on the squeaky floorboards page.
Pilot, clearance and length
Old pine wants a pilot even when a packet says the point is sharp. Reviews on the Ulti-Mate floorboard screws say dense boards needed one, and the bullets do not require it. A pilot slightly narrower than the screw, only as deep as the joist bite, matters more within about 50 mm of a board end. No pilot on a chipboard-screw bullet is not a promise for a Victorian floorboard. A partial thread, as on the named 4.2 x 50 mm floorboard screw, lets the shank slip through the board. A fully threaded chipboard screw, such as the 4.0 x 40 mm box, needs a clearance hole or firm pressure, or the threads can leave the sheet proud. Which screw that is belongs on the chipboard or tongue-and-groove page. Countersink only enough for the head to sit flush.
Drive the screw and stop
Use a drill-driver with a clutch before an impact driver. On the tongue-screw reviews, one long-term user preferred the drill-driver, and sheared heads were the complaint when the drive was too fierce. Phillips, Pozidriv, Torx and square do not share a bit. A cam-out in the last two turns is how a head shears on the Ulti-Mate boxes. Seat the head flush. A proud head telegraphs through underlay, and a head driven far below the face is harder to back out. Space screws at no more than 300 mm along the joist, and keep them out of the bay. Drive beside a loose nail, into the same joist, if the old hole is already split.
When to stop and call someone
Stop when the floor bounces between the lines you marked. A screw cannot repair a cut, rotten or over-spanned joist. Flats with a fire or sound barrier in the floor are not a screw-chart job. If the only access is through a fitted carpet, leave this sequence.
Common questions
How do you find the joist without lifting every board?
Follow the existing nail lines or a magnet along the boards, then mark the centre. You do not need every board up if one lifted board, or a hatch, has already shown you pipes and cables and the lines repeat at a steady spacing. If the lines are irregular, or the floor has been patched, lift a board at the squeak before you drive a row of screws into a guess.
Do you need a pilot hole in old pine?
Yes, as a working rule on dense old pine, even when the screw packet does not ask for one. Reviews of the Ulti-Mate floorboard screws say old boards wanted a pilot. Drill a hole slightly narrower than the screw, on the joist line, and countersink only for the head. Chipboard is less likely to split, and a clearance hole still helps a fully threaded screw pull the sheet down.
How long should the screw be if the board is bare?
Match it to the thickness you measure. For bare 18 mm chipboard the practical length on UK guides is 45–50 mm, against an NHBC minimum of 36 mm. For bare 22 mm board the practical length is 55–60 mm, against a 44 mm minimum. A 40–50 mm screw is the range some repair guides use for boards about 18–25 mm thick. The point must enter the joist, and the spare length should stay short of any service.
How do you avoid cables and pipes?
Look in the void before you drill. A cable through a joist should be at least 50 mm from the top or bottom, or protected, under the BS 7671 guidance NICEIC explains. Many older joists were notched anyway. Mark what you see, keep screws on the joist centre you have checked, and stop if you smell gas, strike metal, or see water. A screw longer than the board plus a short bite is the usual way a fixing reaches a service.
When should you stop and call someone?
Call a joiner if joists are cut, rotten, over-spanned, or the deck has to be rebuilt, or if the floor bounces after the boards are tight. Call an electrician or a Gas Safe engineer if you cannot see the void and you suspect a cable or a pipe. A flat with a fire or acoustic barrier in the floor is not a job for a box of screws and a Saturday afternoon.
Related pages
Sources
Public UK sources and amazon.co.uk listings, checked on 19 October 2026. Shelf prices and star lines are the figures in the display file. Aisle prices outside amazon.co.uk are context, not these shelf prices.
- NHBC Standards 6.4.19 Floor decking (retrieved 19 October 2026)
- NHBC Standards 2025 Chapter 6.4 (retrieved 19 October 2026)
- NICEIC on Voltimum: cables installed in walls and floors (retrieved 19 October 2026)
- UK Construction Blog: screws for chipboard flooring (retrieved 19 October 2026)
- Southern Timber: chipboard sheet materials (retrieved 19 October 2026)
- Wickes: flooring screws (retrieved 19 October 2026)
- BSI BS EN 14592:2022 timber fasteners (retrieved 19 October 2026)
- ToolStore UK: how to fix squeaky floorboards (retrieved 19 October 2026)