Fix a loose or bouncy deck board

Find why a deck board bounces, then re-fix it firmly with the right screws so it stops moving.

DK-01Find the cause of the bounceWalk the deck and press down along the board to find exactly where it moves. Look underneath if you can get access, or lift the board slightly at the loose point. It's usually one of three things: the screws have pulled loose, the joist underneath has sagged, or the joist has started to rot.

DK-02Gather your tools and materialsYou'll need a cordless drill/driver, a pozidriv or square bit to match your screws, new decking screws, and a scrap of treated timber for a packer if the joist has dropped. Have some wood preservative on hand for any bare timber you expose.

1 each · Cordless drill/driver

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10 each · Decking screws 5mm x 60mm

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1 each · Treated timber packer offcut

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1 tin · Wood preservative/end-grain sealant

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DK-03Check for cables and pipes before you drillMost decking jobs are just timber into timber, but garden lighting cables and pipework for an outdoor tap sometimes run through or near joists. If your deck has any lighting, sockets or a tap nearby, isolate that circuit at the consumer unit before drilling near it, and know where your stopcock is (usually under the kitchen sink) in case you hit a pipe. If in doubt, have a quick look underneath before you drill anywhere new.

DK-04Remove the old fixingsUnscrew the failed screws with your driver. If they're rusted or the heads are stripped, use pliers or a claw to lever them out rather than forcing the driver and rounding the head further. Keep the board itself — you'll almost always reuse it.

DK-05Check the joist underneathPush a screwdriver point into the top of the joist where the board sat. If it's firm, you're fine to refix straight into it. If the screwdriver sinks in easily or the wood feels spongy, the joist is rotten and needs proper repair or replacement — that's a bigger job than this guide covers, so don't just screw back into rotten timber.

DK-06Pack out a sagged joist if neededIf the joist itself is sound but has dropped slightly from its support, slide a treated timber packer underneath to bring it back level with its neighbours. Screw down through the joist into the packer and the support below to lock it in place.

4 each · Decking screws 5mm x 100mm

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DK-07Re-fix the boardDrill a pilot hole first if the board is hardwood or close to the end, to stop it splitting. Fix with two decking screws per joist, driven straight down about 5mm in from the edge of the board, so the heads sit flush or very slightly below the surface.

DK-08Check the boards either sidePress down on the neighbouring boards too — if one board's fixings have failed, others nearby are often close behind. It's quicker to sort them now than to be back out here again next month.

DK-09Treat any bare timber and tidy upDab wood preservative onto any cut ends or exposed bare timber to stop water getting in. Sweep up sawdust and old screws, and dispose of the rusted fixings safely rather than leaving them in the garden.

1 tin · Wood preservative/end-grain sealant

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