Can I use reclaimed timber, and what should I check first?

Old timber is frequently denser, straighter and more stable than new, because it was slower grown and it finished moving decades ago. It is also full of surprises, and every one of the checks below exists because somebody skipped it and paid for a blade, a planer knife or worse.

Safety

What you'll need

• A strong magnet or a metal detector
• A nail puller, pincers and a hammer
• A screwdriver for probing
• A moisture meter
• A wire brush and a scraper
• Gloves, eye protection and a mask

Step by step

1. Find the metal before anything else.Run a strong magnet or a cheap metal detector over every face and both edges, slowly, and mark every hit. Old nails snap off below the surface and leave no visible head. This step protects your blades, your planer knives and your face.
2. Pull, punch or cut out every fixing you find.Pull nails from the back where you can so the face is not damaged. Punch broken shanks right through if they will go. Where a snapped nail will not move, either cut that section out or mark it clearly and route your cuts round it.
3. Probe for decay.Push a screwdriver firmly into the ends, into any dark or discoloured area, and into anywhere that was in contact with masonry or the ground. Sound timber resists; decayed timber gives and lifts in soft strings. Cut back well past anything soft.
4. Look for active insect attack.Round flight holes are evidence that beetles were once there; fresh, pale bore dust below them and clean sharp-edged holes suggest they still are. Old holes with grey dust and no fresh frass are historic damage. If in doubt about activity, keep the timber isolated and out of the house until you have decided.
5. Identify the coatings.Paint on anything from before about 1992 may contain lead. Old exterior timber may be creosoted, which has a distinctive smell, is a skin and respiratory irritant and is restricted for consumer use. Both are reasons to reject a piece for indoor use rather than to attempt to strip it.
6. Check the moisture content and the condition.Timber salvaged from a roof is bone dry; timber from a demolition site that has been stacked outside for a year is not. Anything going into a heated house needs stacking indoors to acclimatise as if it were new.
7. Assess it as timber, finally.Sight for bow, spring and twist as you would at a merchant, allow for losing several millimetres of thickness to cleaning up, and expect the finished section to be smaller than what you started with.
8. Clean it up with tools you do not mind blunting.Even after magnet checking, reclaimed timber has grit driven into the surface that dulls edges fast. Use an old blade or a cheap electric planer for the first pass and save your good irons for after the surface is clean.
9. Never use it structurally without a proper assessment.Reclaimed timber has no strength grade, its history is unknown and its section may have been reduced by decay or notching. For anything holding weight, use graded new timber or get a structural engineer to assess the specific pieces.

Tips

• Old floorboards, roof joists and church or school furniture are the best sources of usable reclaimed softwood; scaffold boards, railway sleepers and pallets all carry treatments or contamination and want more thought.
• Buy more than you need. Losses to metal, splits and decay on reclaimed stock routinely run to a quarter or more of what you started with.
• The reason old pine looks so much better than new is growth ring density — a slow-grown board has many narrow rings and a fine even texture. Hold a board up and count the rings across an inch to judge it.

Common mistakes

• Putting reclaimed timber through a thicknesser or a planer without checking it — A snapped nail meeting a planer knife at speed destroys the knife, can crack the cutter block, and throws fragments. It is the single most expensive mistake in this whole area and it is entirely preventable with a magnet.
• Sanding old paint to clean a board up — Pre-1992 paint may be lead-based and dry sanding it produces a fine dust that is genuinely dangerous, especially to children. If you cannot identify the paint, do not sand it — plane the surface off with the waste captured, or use the piece somewhere the paint can stay.
• Bringing timber with active woodworm into the house — Adult beetles emerge and can reinfest other timber. Isolate it, deal with the infestation, or do not use it. Historic holes with no activity are a different matter and are usually just character.

Questions people ask