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What to Do With Old Deck Boards: Sort Before You Skip

Sound boards make raised beds, compost bays and fencing. But treated timber rules out some uses entirely, and that is the first thing to establish.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
A stack of sawn timber lengths with the cut ends facing the camera
Photo: freestocks-photos, Pixabay Content License, via Pixabay
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Establish what the timber is treated with first. That one question decides which of these uses are open to you — and it rules out two of them completely.

Sort the pile first

This table answers the question on its own
ConditionTestUse
SoundScrewdriver will not penetrateAny project
Split at the endsSplits run inward from endsCut back a foot, use the rest
CuppedVisible curve across the widthCut into shorter straight pieces
Soft patchesPoint sinks in at spotsShort offcuts only
Soft right throughCrumblesDisposal

Short lengths are more useful than they sound

Raised bed sides, compost bay slats, path edging and shelving all want short straight pieces. A board with wrecked ends and a sound middle is still worth keeping.

What the treatment rules out

Burning. Always.

Never burn treated decking

Preservative compounds go into the smoke and concentrate in the ash. That is harmful to breathe and harmful spread on a garden, and it is illegal in many places. This applies to a fire pit, a wood burner and a bonfire alike. Untreated hardwood decking can be burned — establish that it really is untreated first.

Food-growing beds, if the timber is old. Decking treated with chromated copper arsenate was widely used until it was phased out of residential use in the mid-2000s, and it contains arsenic.

If you do not know the age or treatment:

  • Use the boards for ornamental beds rather than vegetables, or
  • Line the inside of the bed with heavy plastic so soil does not sit against the timber

Good uses for sound boards

  • Raised bed frames — already the right thickness, already weathered
  • Compost bays — slatted sides from offcuts
  • Cold frames — a low box and an old window
  • Path edging — short lengths, pegged
  • Fence repairs — gravel boards, replacement rails
  • Shed shelving and a potting bench
  • Planter boxes

Boards with a grooved face can be laid groove-down so the flat side shows.

Disposing of what is left

  • Household waste or construction waste facility that accepts treated timber — most do
  • Not garden waste collection, which gets composted
  • Not burned
  • Call ahead for large quantities — some sites cap household construction waste per visit

Common questions

What can you do with old deck boards?

Sound boards have plenty of uses: raised bed frames, compost bays, cold frames, path edging, fence repairs, shed shelving, planters and garden furniture. The first thing to establish is what the timber is treated with, because that rules out some uses. Boards that are cupped, split or soft at the ends are only good for short pieces, and anything that crumbles or is soft right through has rotted and belongs in disposal rather than a project.

Is treated decking safe for raised beds?

Modern treatments are generally considered acceptable for garden use, but older timber is a different question. Decking treated with chromated copper arsenate, widely used until it was phased out of residential use in the mid-2000s, contains arsenic and is not something to put around food crops. If you do not know the age or treatment of the boards, the cautious approach is to use them for ornamental beds rather than vegetables, or to line the inside of the bed with heavy plastic so soil does not sit against the timber.

Can you burn old deck boards?

No, not treated ones, and most decking is treated. Burning preservative-treated timber releases the preservative compounds into the smoke and concentrates them in the ash, which is genuinely harmful to breathe and to spread on a garden. It is also illegal in many places. This applies to a fire pit, a wood burner and a bonfire alike. Untreated hardwood decking can be burned, but establish that it really is untreated first.

How do you dispose of old treated decking?

Through a household waste or construction waste facility that accepts treated timber, which most do as general or hazardous waste depending on the treatment and the jurisdiction. It should not go in garden waste collections, which are composted, and it should not be burned. Call ahead if the quantity is large, since some sites limit how much construction waste they take from households at one time.

What are the best garden uses for old decking?

Raised bed frames and compost bays are the most popular because deck boards are already the right thickness and have survived years outdoors. Beyond those, cold frames, path edging, a potting bench, shed shelving, planter boxes and repairs to existing fencing all use short lengths well, which suits boards with damaged ends. Boards with a grooved face can be laid groove-down so the flat side shows.

How do you tell if old deck boards are worth keeping?

Press a screwdriver into the board, particularly at the ends and anywhere that stayed wet. Sound timber resists; wood that takes the point easily has rotted and is not worth working with. Then look along the length for cupping and splits — a cupped board can often be cut into shorter straight pieces, and splits usually run from the ends inward, so cutting back a foot frequently recovers the rest.

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