What is the difference between redwood and whitewood timber?

These are trade names for the two softwoods that make up the great majority of a UK merchant's stock, and almost nobody explains them at the counter. You will see them on price lists as "redwood PAR" and "whitewood carcassing", and knowing which is which prevents both overpaying for a hidden noggin and finishing a windowsill in the wrong timber.

Step by step

1. Recognise redwood.Scots pine, sold as redwood, red deal or European redwood. Warmer honey to pinkish colour, clear difference between the pale sapwood and the darker heartwood, resinous, generally fewer and larger knots. This is what "pine" usually means when a joinery shop says it.
2. Recognise whitewood.Norway spruce, sold as whitewood, white deal or European whitewood. Pale, almost uniform cream colour with no visible heartwood distinction, less resinous, and covered in small tight knots. Most CLS and most cheap PAR is whitewood.
3. Use redwood for joinery and anything that gets a finish.It machines more cleanly, sands better, takes stain and varnish more evenly and looks like something when it is finished. Skirting, architrave, window boards, shelving, furniture and anything that will be seen.
4. Use whitewood for structure and hidden work.Studs, noggins, battens, joists, framing, formwork. It is cheaper, lighter for the same section and structurally graded to the same classes, and none of its cosmetic disadvantages matter once it is behind plasterboard.
5. Understand the preservative difference, because it decides outdoor use.Redwood sapwood absorbs preservative readily. Spruce is much harder to treat and often needs to be incised — pierced with small slits — before pressure treatment will penetrate at all. For anything outdoors, check what the timber actually is and that it has been treated to a use class suited to the exposure.
6. Expect to be sold whichever is in stock.Many merchants list "softwood" without distinguishing, and stock varies. If it matters, say which you want when ordering and check what turns up — the colour difference is obvious in daylight.

Tips

• "Deal" is an old word for a sawn softwood plank, so red deal and white deal are the same two timbers under older names. Some yards still use them.
• Whitewood's small hard knots blunt blades faster than redwood's larger softer ones, and they are more likely to blow out when you plane across them.
• If you are painting rather than staining, the difference matters much less — both need knotting solution over resinous knots first or the resin bleeds through.

Common mistakes

• Buying whitewood for a stained or varnished finish — The colour is flat and the many small knots show as a rash of dark dots under a clear finish. Redwood stains far better, and even it needs care to avoid blotching.
• Assuming untreated whitewood is fine outdoors because it is a softwood like redwood — Spruce is both perishable and hard to treat. Untreated whitewood outdoors has a very short life, and "treated" spruce that has not been incised may have very shallow penetration.

Questions people ask