Damp after a flood: drying out your Doncaster home properly

Doncaster knows what flooding does to a home. In November 2019, flooding directly affected 897 properties across the borough, according to the City of Doncaster Council flood recovery report. The independent Section 19 investigation found it primarily affected Bentley, Scawthorpe, Fishlake, Conisbrough and Tickhill (RAB Consultants, Doncaster Section 19 flood investigation). We have local guides for Bentley, Fishlake, Thorne and Hatfield, Conisbrough and Mexborough and Tickhill and Rossington. Long after the water has gone, walls, floors and the space under them can stay wet, and that is where lasting damp and mould begin. This guide covers the first steps, drying out properly and how to tell when the house is ready to put back together. It is general information, not a diagnosis.

First steps after the water goes down

• Check with the emergency services that it is safe to go back in.
• Do not turn on water, gas or electricity until your utility company or a qualified engineer says they are safe.
• Take photos of the damage and the flood water line before you clear up, and speak to your insurer about what you can move and throw away.
• If you rent, your landlord is responsible for repairs to flood damage.
• Floodline (0345 988 1188, 24 hours) can give information and advice.

Source: GOV.UK: what to do after a flood.

Cleaning up safely

Flood water can carry sewage and other contaminants. UKHSA advises rubber boots, waterproof gloves and a plastic apron or overalls while cleaning, and washing your hands with warm water and soap after each session. See UKHSA: flooding and health, advice for the public.

Drying out: what actually works

• Heat, dehumidifiers and ventilation together. UKHSA says all three help. Have gas or oil central heating checked by a qualified engineer first, then keep the thermostat between 20°C and 22°C for steady drying.
• Never run petrol or diesel generators or dryers indoors. Their exhaust contains carbon monoxide. Keep any heater or dryer well ventilated.
• Open up under the floor. Unblock air bricks to underfloor spaces so air can cross the void. With timber floors, check underneath, as dirty water trapped in the void may need pumping out.
• Keep on top of dust and silt as floors and walls dry, and vacuum regularly.

Why walls stay damp after a flood

Brick, plaster, screed and timber soak up water and give it back slowly. Surfaces can feel dry while the core of a wall is still wet. Soaked plaster and plasterboard often have to come off so the masonry behind can dry. Flood water also leaves silt and salts in walls, and salts can keep drawing moisture from the air, so a tide mark can linger long after the flood. In houses with a timber ground floor, a wet void and blocked air bricks can lead to damp joists and a musty smell. Our guide to cellar damp, floor voids and air bricks covers that in more detail.

Check before you replaster or redecorate

The most common mistake after a flood is putting a house back together too soon. New plaster, paint or flooring over wet masonry traps the moisture, and mould or blown plaster follows. Before reinstatement, ask for:

1. Moisture readings on the affected walls and floors, repeated over time so you can see them falling.
2. A written note of which materials were removed, which were kept and why.
3. A check that air bricks are clear and that the ground outside is not built up against the wall.
4. Advice on whether any remaining damp is from the flood or from another cause; see condensation vs rising damp and penetrating damp.

Preparing for next time

You can GOV.UK: check your long term flood risk, GOV.UK: get flood warnings by text, phone or email, and make a personal flood plan using GOV.UK: protect yourself from future flooding. If you rent, keep copies of anything you report to your landlord, and see our guide to damp and mould in rented homes.

Need a second opinion?

If walls are still damp weeks after a flood, or mould keeps coming back, tell us what you can see through the enquiry form. With your consent, we will pass your enquiry to a local damp and mould professional who can check readings, talk it through and, if needed, arrange a survey and written quote.

Sources and further reading

City of Doncaster Council flood recovery report; RAB Consultants, Doncaster Section 19 flood investigation; GOV.UK: what to do after a flood; UKHSA: flooding and health, advice for the public; GOV.UK: check your long term flood risk; GOV.UK: get flood warnings; GOV.UK: protect yourself from future flooding.

Related guides

• Damp proofing in Bentley, Doncaster
• Damp proofing in Thorne and Hatfield
• Damp proofing in Conisbrough and Mexborough
• Damp proofing in Rossington, Bawtry and Tickhill
• Rising damp and damp proof courses
• Doncaster areas and DN postcodes
• Cellar damp and tanking in Doncaster
• Black mould removal and causes
• Damp survey cost in Doncaster
• Damp and mould in rented homes

Frequently asked questions

How long does a house take to dry out after a flood?

It depends on how deep the water was, how long it stood, what the walls and floors are made of and the time of year. Thick masonry and solid floors can take a long time. Moisture readings taken over several weeks are a better guide than how a wall looks or feels.

Can I use my central heating to dry the house?

UKHSA advice is to have gas or oil central heating checked by a qualified engineer before turning it on, then keep the thermostat between 20°C and 22°C for steady drying, alongside dehumidifiers and good ventilation.

Who pays for flood repairs if I rent?

GOV.UK says your landlord is responsible for repairs to your home if you have flood damage. Tell them in writing, take photos and keep copies.

Will mould go away once the house has dried?

UKHSA advice is that mould should disappear as the home dries out, and that if it persists you should contact a specialist. Mould that keeps returning after drying often means moisture is still in the wall or floor.