Which hardwood should I use — oak, ash, beech, iroko or poplar?

Hardwood is bought differently from softwood: by the piece or the cubic metre rather than the length, often from a specialist rather than a general merchant, and usually in random widths. Choosing well is mostly a matter of matching three properties to the job — hardness for wear, durability for damp, and stability for width.

Step by step

1. Choose oak where appearance and longevity both matter.European oak is hard, strong, dimensionally reasonable and genuinely durable outdoors in its heartwood. Worktops, tables, stair parts, thresholds, gates, garden furniture, exposed structural frames. It is heavy, hard on tools, and it reacts with iron and with some finishes.
2. Choose ash for toughness and pale colour.Ash is springy and very tough — the traditional timber for tool handles and bentwood chairs — with a bold open grain and a light, almost white colour. Excellent for furniture and interior joinery. It has no useful outdoor durability at all.
3. Choose beech for wear surfaces indoors.Even, close, almost featureless grain, very hard, turns and machines beautifully, and takes a fine edge on a moulding. It is the classic chopping block and workbench timber. It moves a lot with humidity and rots quickly in damp, so keep it dry.
4. Choose iroko or sapele for outdoor joinery.Iroko is durable, stable and used for external doors, windows, sills and garden furniture — often described as a substitute for teak. Sapele is a mahogany-like timber widely used for windows and doors. Both are dearer than oak in some sections and both dull tools.
5. Choose poplar or tulipwood for painted work.American tulipwood, often sold loosely as poplar, is a light, cheap, stable hardwood with a bland greenish-grey colour. Under paint it is excellent: it machines cleanly, holds a crisp moulding, dents less than softwood and moves less than pine. It is useless outdoors.
6. Buy birch as plywood rather than as boards.Solid birch boards are uncommon in UK merchants, but birch plywood is everywhere and is the best general-purpose sheet material there is for visible work. If a job calls for birch, it usually means the ply.
7. Check the moisture content for indoor work.Hardwood for interior joinery should be kiln dried and then acclimatised in the room it will live in. A wide oak board fitted straight from a cold store into a heated house will shrink noticeably and can split at its fixings.
8. Buy hardwood in person if you can.Widths, colour and figure vary enormously piece to piece, and a rack of oak contains boards that will and will not look right next to each other. Where the job is visible, pick the boards yourself and buy them all at once.

Tips

• Ask for the timber "through and through" or from one board if you want colour and figure to match across a project — different trees give visibly different colour, especially in oak.
• Hardwood is often sold rough sawn and oversize, so a nominal 25mm board finishes at around 20mm once you have planed it. Buy a size up from the finished thickness you want.
• Most hardwoods dull blades and cutters faster than softwood, and iroko and some tropical species are notably abrasive. Budget for sharpening, and do not use your best plane iron on reclaimed hardwood.
• Some tropical hardwood dust — iroko particularly — causes respiratory and skin irritation in a proportion of people. Extraction and a mask are worth it even for small quantities.

Common mistakes

• Using beech or ash for anything outdoors — Both are classed as perishable. An ash gate or a beech garden bench will show decay within a couple of seasons, no matter what finish is applied, because the finish is not what keeps water out of a joint.
• Fixing oak with ordinary steel screws or nails — Oak's tannin reacts with iron in the presence of moisture and produces a black stain that spreads into the timber round every fixing. Use stainless steel, or a coated fixing specifically rated for oak.
• Buying wide hardwood boards for a panel and fixing them rigidly — A wide board moves substantially across its width with the seasons. Fixed at both edges, it either splits or pushes its frame apart. Panels need to float or be made narrow and glued up.

Alternatives

• Hardwood-faced plywood: Oak, ash or walnut veneered ply gives you the appearance of the timber with none of the movement, at a fraction of the cost, on any job where you can hide or lip the edges.
• Hardwood lipping on a cheaper core: A solid hardwood edge glued to an MDF or ply panel gives a real wearing edge, a real profile and a stable board. This is how almost all commercial furniture is built.
• Softwood, painted: If the finish is opaque, a well-chosen redwood or a poplar costs far less and, for anything not taking heavy wear, is entirely adequate.

Questions people ask