Condensation or rising damp in a London flat?

Condensation in flats

Flats concentrate moisture: a household cooking, washing and drying clothes in a small space, often with a bathroom that has no window and an extract fan that runs into a void rather than outside. External walls of converted houses and post war blocks can be cold, especially at concrete lintels and slab edges, and that is where the moisture settles.

• Mould in corners, behind furniture and around windows
• Streaming windows and wet sills in the morning
• Worse in winter and in rooms that are cooler
• No sharp edge or tide mark; follows cold surfaces

Rising damp in lower ground and ground floor flats

True rising damp needs a wall in contact with damp ground and no working damp proof course. In London lower ground flats it is diagnosed often and found rarely. Front area drains, pavement vaults, raised rear patios, decking against the wall and leaking soil stacks produce the same tide mark, and none of them is fixed by injection.

Penetrating damp and leaks from elsewhere

Water from a parapet gutter, a valley, a cracked render, a window head or a flat above can travel a long way inside a building before it shows. The damp appears in your flat; the defect is somewhere else. Damp that follows rain, appears on upper floors or on ceilings, or sits under a specific feature outside is almost always this kind.

Why it matters who is responsible

Under most leases, the structure, roof, external walls and shared services are the freeholder's to repair, and the inside of the flat is the leaseholder's. A leaseholder who pays for damp proofing inside the flat for a problem that starts in the structure has paid for the wrong thing, and the water keeps coming. A tenant whose landlord blames condensation without investigating may be living with a building defect.

An independent report that records the source, the route and the evidence is what moves these situations on. Because ATi does no remedial work, the report has no interest in which answer it reaches.

What you can check yourself

Noting these with dates and photos helps any surveyor, and is useful evidence in its own right.

• Does the damp follow the rain, the cold, or neither?
• Is it on an outside wall, a party wall, a ceiling, or under a window?
• Do the kitchen and bathroom fans run and extract to outside?
• Is there anything outside at the same spot: a downpipe, a hopper, a raised patio, a front area drain?
• Does the flat above or next door have a bathroom or kitchen in the same position?

Questions

Related

• Condensation and Mould
• Rising Damp
• Penetrating Damp
• Awaab's Law: damp and mould in rented homes
• Buying in London: when to get a damp survey
• What does a damp survey cost in London?
• Woodworm and rot: what a treatment quote should look like