External timber doors take a beating from the British weather — sun, rain and frost all work away at the wood, and without protection an oak or hardwood door can fade, swell or crack. The best way to look after one is to oil it: the oil soaks into the timber, guards against moisture and UV, and lets the natural grain show through. Here's how to treat an external wood door properly — whether it's oak or hardwood — and how often to top it up. One thing matters from the very start, though: an external timber door must be fitted under a porch or canopy to shield it from the worst of the weather — without one, no finish will last.
What you'll need to oil an external door
| What you'll need | Why |
|---|---|
| Impranol Oil | Our recommended finish for external doors — soaks in and protects |
| Lint-free cloth or brush | For thin, even coats |
| Fine-grit sandpaper | Smooths the surface and keys it between coats |
| Clean, dry, ventilated space | Lets each coat cure properly |
| Gloves and safety goggles | Basic protection while you work |
| Masking tape and dust sheets | Protects glazing, hardware and floors |
How to treat an external wood door, step by step
- Prepare the space. Lay the door flat somewhere clean, dry and well-ventilated, and cover nearby surfaces. Make sure the door is clean, dry and dust-free, and sand any trimmed edges before you start.
- Sand the door. Lightly sand the whole surface with fine-grit paper so it's smooth and ready to take the oil, then wipe away the dust.
- Apply the first coat. Test the oil on an offcut or hidden area first. With a lint-free cloth or brush, work a thin, even coat over every face and edge, wipe off any excess, and leave it 24 hours to dry.
- Sand between coats. Once dry, lightly sand again to knock back any raised grain, and wipe clean.
- Build up the coats. Apply a second thin coat, and a third for exposed doors, letting each dry for 24 hours. Three coats gives the best protection.
How often to re-treat and maintain it
Oiling isn't a one-off. A quick wipe-down keeps the door looking its best, and a fresh coat every so often keeps the protection topped up. Just as important is shelter: a porch or canopy is essential, not optional — direct rain and sun are what break a finish down, so every external timber door should sit under one, especially on a south or south-west facing entrance.
| Task | How often |
|---|---|
| Wipe clean with a damp cloth and mild soap | As needed |
| Check seals, hardware and glazing | Every few months |
| Re-apply Impranol Oil | Yearly, or as the door needs it |
Frequently asked questions
How often should you oil an external door?
Once a year suits most doors; exposed, south-facing doors may need it more often. Re-oil whenever the finish starts to look dry or dull.
What's the best oil for an external oak door?
We recommend Impranol Oil — it soaks into the timber, protects against moisture and UV, and keeps the grain looking natural.
Do you need to treat both sides and all the edges?
Yes — seal every face and edge, including the top and bottom, before the door is hung. Bare edges let moisture in and cause swelling.
Can you paint over an oiled door?
Not directly; paint won't bond over oil. You'd need to strip and sand back to bare timber first, so if you want a painted colour, choose a suitable exterior finish from the outset.
Does an external wood door need a canopy?
It's strongly recommended. A porch or canopy shields the door from direct rain and sun and significantly extends the life of the finish.
Keep your door protected for years
Treated well, a solid timber door will look after your home for decades. Whether you're finishing an oak external door or a hard-wearing hardwood external door, a few coats of oil and the odd top-up are all it takes. Not sure which finish suits your door? Our team is always happy to help.
Related reads
| How to Weatherproof Your Doors | Seal out draughts and rain |
| Maintaining Your Internal & External Doors | Keep every door in good order |
| How Energy Efficient Are Your Doors? | Cut heat loss through your doors |
