Drying out after a water leak typically takes two to six weeks, and longer for a saturated concrete screed or thick solid walls. Dehumidifiers and air movers run until moisture readings return to a dry standard, not until the surface looks dry. Insurers insist on it because reinstating over wet materials leads to mould, lifted floors and a second claim.
The leak has been found and fixed. The plumber has gone. And now there are two large machines humming in your living room, a damage management firm is visiting every week with a meter, and nobody will tell you when the floor can go back down. It is frustrating, especially with the disruption of a leak already behind you. This guide explains what the drying stage is doing, why it takes as long as it does, and why trying to hurry it nearly always backfires.
The leak has to be fixed first
It sounds obvious, but it is the most common reason drying stalls. If water is still arriving, no amount of equipment will bring the readings down, and the drying contractor’s weekly report will show a flat line instead of a downward one. That flat line is also what makes an insurer start asking whether the damage is gradual rather than sudden.
If a plumber has repaired the visible fault but the readings refuse to move, the original leak may not have been the only one, or may not have been the leak at all. This is where a non-invasive trace and access survey earns its place: it confirms the source is closed before weeks of drying are wasted. Our piece on when a plumber could not find the leak covers that situation.
Surface dry is not dry
Water from a leak does not sit on top of things. It soaks into plaster, screed, timber joists, chipboard flooring, insulation and the block or stone behind the plaster. The surface of a wall can feel dry to the hand within a few days because air is moving over it, while the material a few centimetres in is still saturated. Paint over that and the moisture pushes out through the new finish, blistering it. Lay a new floor over it and the boards cup and lift.
Drying is therefore measured, not judged by eye. The contractor takes readings with a moisture meter, and often a deeper probe, at fixed points on each visit, and compares them with a reading from an unaffected part of the same building. When the wet areas match the dry reference, the material is dry. Until then, it is not.
How long each material takes
These are typical ranges under managed drying with equipment running continuously. Real times depend on how long the leak ran, how warm the building is and how well it is sealed.
| Material | Typical drying time | Why |
|---|---|---|
| Plasterboard and skim | 1 to 3 weeks | Thin and porous, dries fastest, but often replaced if saturated |
| Timber joists and floorboards | 3 to 6 weeks | Dense, holds water deep in the grain, must dry slowly to avoid warping |
| Chipboard flooring | Usually replaced | Swells and loses strength once wet, rarely recovers |
| Concrete screed | 4 to 12 weeks or more | Holds a large volume of water, releases it slowly through one face |
| Solid stone or cob walls | Many weeks to months | Thick, dense and often lime-plastered, very slow to give up moisture |
| Insulation in floors and walls | Usually replaced | Mineral wool slumps, foam traps water, drying is impractical |
The last two rows are why leaks in Cornwall’s older housing stock take longer than a modern house in a new estate at Newquay. A granite cottage with metre-thick walls and a slate floor laid on earth holds a great deal of water, and forcing it out too fast with heat can crack lime plaster and lift limewash. Drying here is a gentler, longer job.
What the equipment is doing
- Dehumidifiers pull water vapour out of the air. As the air dries, moisture in the walls and floor evaporates into it to restore the balance, and the dehumidifier removes that too. Refrigerant units suit warm rooms; desiccant units keep working in cold ones, which matters in an unheated holiday let in January.
- Air movers keep air flowing across wet surfaces so evaporation does not stall in a still layer next to the wall.
- Heat mats and injection drying are used on screeds and under floating floors: warm, dry air is pushed into the void so the slab dries from both faces instead of one.
- Containment, usually sheeting off the affected room, stops the machines trying to dry the whole house and the damp Cornish air outside it.
The equipment needs to run all the time. Switching it off overnight to save electricity, or opening windows on a wet day, can add a week. Most insurers reimburse the electricity cost on a claim, so keep the meter readings from start to finish and ask.
Why the insurer insists on it
From the insurer’s side, the drying certificate is the line between one claim and two. If the reinstatement goes ahead over materials that are still wet, the new floor lifts, the new plaster blows, mould appears behind the new kitchen units, and the whole job has to be done again. The drying contractor’s final report, showing readings at the dry standard on every monitored point, is what releases the reinstatement stage.
It also protects you. Damage that appears after a rushed reinstatement is very hard to attribute, and an insurer may argue it is a new event, or gradual, or a workmanship issue. A documented drying phase removes that argument. The loss adjuster will normally want to see the drying log alongside the leak detection report.
What goes wrong when people rush it
- New laminate or engineered flooring cups within weeks because the screed beneath was still releasing moisture. We see this often after a leak that was fixed by a plumber and redecorated by the homeowner without any drying at all.
- Paint blisters and plaster crumbles as trapped water pushes out through the new finish.
- Black mould appears behind furniture and inside cupboards on the affected wall.
- The smell never goes. A musty, earthy smell after a leak is the sign that something is still wet behind the surface.
- The insurer declines the second claim. Reinstating before the drying was signed off can be treated as a failure to mitigate.
Living with it
A few practical points for the weeks the machines are running. Keep doors to the affected area closed and the windows shut, however tempting it is to air the room. Empty the dehumidifier if it is not plumbed to a drain, and note how much water comes out; a falling volume each day is a good sign. Do not move the units or the monitoring points, because the readings need to be taken in the same places every visit. Ask the contractor for a copy of each visit’s readings so you can see the trend yourself. If the readings are not falling after two visits, say so, and ask whether the source has been properly confirmed.
If you have had to move out, or a holiday let is losing bookings, check the policy for alternative accommodation and loss of rent cover. Both are common, both have limits, and both need the insurer to have agreed them in advance.
Frequently asked questions
How long does it take to dry out a house after a water leak?
Typically two to six weeks with dehumidifiers and air movers running continuously. Plasterboard is fastest, timber joists take longer, and a concrete screed or thick stone wall can take two or three months. The drying ends when moisture readings match a dry reference point, not when the surface looks dry.
Can I switch the dehumidifiers off at night?
It is better not to. Drying works by keeping the air consistently dry so moisture keeps moving out of the structure. Switching off overnight lets it stall and adds time. Most insurers cover the electricity used on a claim, so keep a note of the meter readings and ask.
Why is the floor still wet after the leak was fixed?
Either the screed or joists are holding water deep in the material, which is normal and takes weeks, or the leak has not fully stopped. If readings are not falling over two weekly visits, have the source confirmed with a non-invasive survey before any more drying time is spent.
Can I redecorate before the drying is finished?
No. Paint and new flooring trap moisture in the wall or floor, then fail as it tries to escape. Wait for the drying contractor’s final report showing dry-standard readings, then reinstate. Doing it early can also give the insurer grounds to decline any later damage.
Who arranges the drying, me or the insurer?
Usually the insurer appoints a damage management company once the claim is accepted, and pays them directly. If you arrange your own contractor, agree it with the insurer first and keep every report and invoice. Either way, the leak must be located and repaired before drying starts.
Make sure the leak has stopped
If the readings are not falling, the source may not be closed. We confirm exactly where the water came from, and that it has stopped, with a report the drying contractor and insurer can work from. We provide leak detection across Cornwall.
