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Rotten Door Frame At The Bottom
The bottom few inches of an external door frame have gone soft, spongy or crumbly.
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What's happening?
The foot of an external door frame is the wettest piece of joinery in a house. Rain runs down the jamb, splashes back off the threshold, and the end grain at the bottom of the post soaks it up like a wick. The Property Care Association notes that wet rot is typically found where posts and beam ends meet wet walls or the ground — exactly this detail. The paint often looks intact while the timber behind it has gone, because the decay works from the hidden end grain outwards. Press a screwdriver into the post 50mm above the threshold: if it sinks, the frame is no longer doing structural work there, and the door's hinge or keep fixings are relying on soft wood.
What usually causes it?
- End grain at the foot of the jamb sitting on a wet threshold or straight onto concrete with no damp-proof separation
- Ground or paving built up so the frame foot sits at or below outside level, against Approved Document C's expectation that a damp-proof course sits at least 150mm above adjoining ground
- Threshold weatherbar or drip missing, so water blows back under the door and stands in the rebate
- Blocked or missing drainage at the door — a step or porch floor falling towards the frame instead of away
- Failed paint or sealant at the frame-to-brickwork joint, letting water in behind the timber
- Downpipe or gully discharging next to the door and splashing the jamb every time it rains
- Previous repair filled rather than cut out, sealing moisture into the post
Is it dangerous?
Medium, and higher than people expect. The frame foot anchors the door: soft timber there means hinge screws and lock keeps have nothing to hold, which is a security failure as much as a joinery one. Decay that reaches the wall plate, joist ends or the sole plate of a timber-framed wall becomes a structural repair. Rot beside a door is also a moisture route into the floor void, and standing damp in a void invites further decay in timbers you cannot see. If it is a fire door between a garage and the house, a decayed frame no longer holds it in place.
Can I fix it myself?
Limited. Clearing away built-up soil, moving a planter, unblocking a gully and reinstating a weatherbar are all worth doing yourself and may stop the decay spreading. Do not fill a soft post: hardening resins and fillers have a place in the hands of someone who has already cut back to sound timber, but used over decay they hold water in. Cutting out and scarfing in a new frame foot involves supporting the frame and the head above it, and getting the new timber sitting on something that will not wet it again.
When should you call a carpenter?
Call a carpenter as soon as the post is soft to a probe, the door has started to move in the frame, or hinge or lock screws have lost their grip. Call urgently if the decay extends into the threshold or the wall beside it, if there is a musty smell from the floor void, or if you can see fungal growth spreading beyond the timber onto the masonry — that last one needs a specialist look before any joinery is done.
What will the carpenter actually do?
- Probe the frame, threshold and adjacent floor timbers to find the true extent before quoting the cut
- Identify and fix what is wetting the frame — the drip detail, the ground level, the splashing gully
- Support the frame and head, cut the decayed section out to sound timber and scarf in a new treated foot
- Rebuild the threshold with a proper weatherbar, drip and damp-proof separation under the end grain
- Prime and seal all exposed end grain, then reinstate the frame-to-masonry joint
- Rehang the door into sound timber and reset the hinges, keeps and seals so it closes and locks properly
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