Which wood species are best for exterior doors?
The Wood Guide · Choosing and comparing
Buying guideWood for exterior doors
A door that no longer closes is worse than a door that looks weathered. That is why one property counts above all others for exterior doors.
- Stability first
- Only then durability
- Afzelia and meranti dominate
The choice at a glance
With almost any outdoor wood you look first at the durability class. With a door, that is the second question.
An exterior door is caught between two worlds. On the outside thirty degrees of sun and driving rain, on the inside a heated house with a humidity of thirty per cent. That difference pulls at the wood, every day, for years.
A door made of a species that moves a lot sticks in August and leaves a three-millimetre gap in January. A door made of a stable species does exactly the same in both cases: it closes. That is why, for door timber, dimensional stability comes first, and durability second.
A cladding board is allowed to move — it overlaps its neighbour and nobody notices a millimetre. A door sits in a frame with a tolerance of a few millimetres on all sides. The same movement that is invisible on a façade makes a door unusable.
- First requirement
- dimensional stability — does the wood move little?
- Second requirement
- durability class 1 to 3
- Third requirement
- weight — the hinges carry it for years
- Classic
- oak, meranti, afzelia (doussié)
- Modern
- Accoya and thermally modified wood
- Essential
- all six sides treated, including top and bottom
To be fair: the most beautiful door in the most durable wood will fail if the top and bottom edges are left untreated. Those are the two surfaces nobody sees and that absorb the most moisture — and they are the most common cause of a door that warps after five years.
Your door
Wood species
All six sides treated?
The five usual species
| Oak | good | class 2 | average |
| Afzelia | excellent | class 1–2 | low |
| Meranti (dark red) | good | class 2–3 | average |
| Accoya | excellent | class 1 | very low |
| Thermally modified wood | very good | class 2–3 | low |
What a wooden exterior door asks of you
- Check every year — especially the bottom, south and west
- Readjust the hinges — half a turn a year
- Measure the gap — summer and winter; more than 2 mm difference = moisture problem
- Keep the drip edge clear — leaves and dirt hold moisture
The five usual species
| Wood species | Dimensional stability | Durability | Appearance | Maintenance |
|---|---|---|---|---|
| Oak | Good | Class 2 | Classic and timeless | Average |
| Afzelia (doussié) | Excellent | Class 1–2 | Warm reddish brown | Low |
| Meranti (dark red) | Good | Class 2–3 | Calm reddish brown | Average |
| Accoya | Excellent | Class 1 | Light, usually painted | Very low |
| Thermally modified wood | Very good | Class 2–3 | Deep brown right through | Low |
Acetylated softwood moves so little that a coat of paint stays on it much longer — paint cracks because the substrate moves, not because of the paint itself. For a painted door that means repainting every ten years instead of every four. See Accoya.
Which species for which door
Classic front door on show
Oak. Timeless, hard, class 2 and it ages with dignity. Use stainless steel — the tannins turn ordinary steel black.
A door that will be painted
Accoya. The paint lasts considerably longer because the substrate hardly moves.
A door facing south or west
Afzelia or thermally modified wood. That is where the load is greatest and stability counts double.
Keeping an eye on the budget
Dark red meranti. Ask explicitly for the dark red group — light red and white meranti belong indoors.
Front, back, two sides, top and bottom. The top and bottom are end-grain surfaces that absorb moisture ten to fifteen times faster than the faces. Untreated, they soak up water while the rest stays dry — and that imbalance is exactly what makes a door warp.
What a wooden exterior door asks of you
- Check every yearGo over the finish, especially at the bottom and on the south and west sides. Touching up small cracks takes minutes; a coat that has failed costs a door.
- Readjust the hingesA door drops over the years. Half a turn a year keeps the gap even and prevents wear at one point.
- Check the gapMeasure in summer and in winter. If the gap stays the same, the wood is performing well. If it varies by more than two millimetres, there is a moisture problem.
- Keep the drip edge clearThe threshold must be able to drain water. Leaves and dirt hold moisture at exactly the most vulnerable point.
Frequently asked questions about wood for exterior doors
Which wood is best for an exterior door?
Afzelia (doussié) and Accoya for maximum stability, oak for the classic look. With a door, dimensional stability counts for more than durability class.
Why does my wooden door stick in summer?
The wood absorbs moisture from the humid summer air and swells. With species that move a lot that is a few millimetres — enough to stick. See how wood moves.
Do I need to treat the top and bottom of a door?
Absolutely. They are end-grain surfaces that absorb moisture much faster than the sides. Leaving them untreated is the most common cause of a warped door.
Is meranti suitable for an exterior door?
Dark red meranti is — class 2 to 3 and good dimensional stability. Light red and white meranti belong indoors. Always ask about the colour group.
Door timber in perspective
A door isn't judged on how it looks, but on whether it closes.
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Photos via Wikimedia Commons: Alkmaar — Dqfn13, CC BY-SA 4.0 · Ghent — Ferdinand Stöhr, CC0