The Ten-Minute Damp Check, Room by Room

This is a look, not a survey. Ten minutes, no instruments, no lifting carpet. The aim is to catch the boring early signals while they are still cheap.

Work in this order, because it runs wettest-room-first and you will get most of your findings in the first three stops.

Bathroom — two minutes

Look at the ceiling above the shower, the silicone where the bath meets the wall, and the underside of the window frame. Black speckling in silicone is the earliest and most common finding in any home. Check the fan is actually moving air: hold a square of toilet paper to the grille and let go.

Kitchen — two minutes

Under the sink, at the back, with a torch. Then the wall behind the kettle and the hob, and the seal around the washing machine door. Under-sink leaks are slow and quiet and sit in a cupboard nobody looks in.

Bedrooms — three minutes

Pull the bed and any wardrobe away from the coldest exterior wall and look at the wall itself, low down and in the corners. Then the window reveals. Condensation collects where warm air meets the coldest surface, and behind furniture is where it is least disturbed.

Storage and utility — three minutes

Closets on exterior walls, the back of the airing cupboard, the loft hatch if you can reach it, and wherever the boiler or the dryer lives. Smell counts here. An earthy smell in a closed space with no visible growth usually means it is behind something rather than absent.

What to do with what you find

Small and on a hard surface — clean it, dry it, and then work out where the water came from. Cleaning without answering that second question just schedules the same job again.

Size is the honest dividing line. EPA puts the do-it-yourself limit at about ten square feet, roughly a three-foot by three-foot patch; larger than that and the recommendation is to bring in help. Absorbent materials that stay wet — carpet, ceiling tile, plasterboard — usually have to be replaced rather than cleaned, because you cannot get all of it out of the material (EPA, A Brief Guide to Mold, Moisture and Your Home).

Two things not to do: do not paint or caulk over it, and do not treat a smell as nothing because you cannot see anything.

Read the sources

• EPA — A Brief Guide to Mold, Moisture and Your Home — reproduced here; original at https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
• EPA — Ten Things You Should Know about Mold — reproduced here; original at https://www.epa.gov/mold/ten-things-you-should-know-about-mold