Damp proofing in Croydon: an independent survey first

Why the survey comes before damp proofing in Croydon

A great deal of the damp proofing sold in Croydon is sold to a wall that is wet for another reason: a lightwell or patio above the old course, a defective gutter on a party parapet, a bathroom extract ducted into a void, or condensation in a flat that has lost its air changes. We do not sell damp proofing or any other remedial work, so the survey has one job, which is to say which of those it is.

The quote we see most in Croydon is chemical injection along the front and side walls of a 1930s semi, often with a metre of replastering. In most cases the original course is intact and has been bridged: by a block paved drive laid across the front garden, a patio at the back, a rendered plinth, or rubble in the cavity at the base. Injection leaves the bridge where it is.

In Croydon, a large share of homes are flats, and damp proofing quotes are often given to a leaseholder for a problem that belongs to the building. Before paying, check whether the water is coming through the roof, the external walls, the front area or a shared drain, because under most leases those are the freeholder's to repair. Our report states the source and the route, with the evidence a managing agent needs.

Damp proofing methods, briefly

A chemical damp proof course, a physical course, a waterproof render, a drained membrane, a breathable plaster: each is sold as damp proofing, and each answers a different question. The survey's job is to establish which question the Croydon wall is actually asking.

In converted buildings the answer is often outside the flat altogether: a communal gutter, a front area drain, a parapet or a neighbour's raised garden. A damp proofing system inside the flat cannot fix any of those.

Croydon walls, and what they actually need

Croydon's interwar houses have cavity walls with a course two or three bricks above the original ground, and suspended timber floors ventilated by airbricks. They need the ground kept below the course, the airbricks open, the cavity clear at the base and the rainwater working. In the Victorian streets of Thornton Heath and South Norwood the walls are solid, with similar needs.

• Lowering drives and patios, or cutting a drained channel along the wall, where they bridge the course
• Reopening and adding airbricks to ventilate suspended timber floors
• Clearing rubble and mortar snots from the base of the cavity where they bridge to the inner leaf
• Improving extraction and dealing with cold spots for mould in bedrooms and bathrooms

Driveways and the 1930s damp proof course

Paving front gardens for parking is one of the most common changes to Croydon houses, and it is the most common cause of damp in them. The paving is usually laid to suit the pavement and the drop kerb, not the house, and it often ends up level with or above the original course. Rain splashes onto the wall and the paving holds water against the brick, and the damp appears inside at the base of the front wall.

The fix is a channel or a strip of gravel along the wall with the paving cut back to at least two courses below the damp proof course, and a drainage outlet where needed. That is groundwork, not damp proofing.

What proper damp proofing involves in a London building

• A diagnosis in writing, with readings, before any specification
• External and communal faults identified and assigned: parapets, gutters, lightwells, shared drains
• A new damp proof course only on a Croydon wall that genuinely lacks a working one at low level
• Breathable or salt resistant replastering chosen for the wall, not a default system
• Consent considered where the building is listed or in a conservation area
• A record of what was done and why, which a future buyer's surveyor will ask for

Warning signs in a damp proofing quote

• Rising damp diagnosed on an upper floor, or on a party wall with no ground contact
• No inspection of the lightwell, front area, rear yard or parapet
• A blanket timber treatment added to a damp quote
• A guarantee that does not say which walls, or what happens if the cause was elsewhere
• A price for a Croydon terrace with no reference to its solid walls or its lime plaster
• Pressure to agree before a buyer's or lender's deadline

When a damp proof course is the right answer

We are not opposed to damp proofing, only to it being sold as the answer before the question has been asked. Where the readings, the pattern and the building all point to a missing or failed course in a Croydon property, the report recommends one and says how it should be done.

The survey fee is published and fixed before the visit. In Croydon, where replastering and making good in a period flat is expensive and disruptive, establishing whether the work is needed before it starts is the economical step.

The report gives you the cause, the responsibility and a specification. In Croydon that often means a letter to a freeholder or managing agent with the evidence attached, before any work inside the flat is considered.

For the full picture of what a survey here involves, see damp surveys in Croydon.

Around Croydon

Purley, Coulsdon and Selsdon

Interwar and post war houses on larger plots, many on slopes. Drives, retaining walls and garden run off cause most of the damp we see.

Thornton Heath, Norbury and South Norwood

Victorian and Edwardian terraces alongside interwar streets. Raised yards, rear additions and bays are the usual sources.

Damp proofing questions in Croydon

Nearby

• Damp proofing in Bromley

Book a survey before you pay for damp proofing

Get the cause, and who is responsible for it, in writing before you pay for damp proofing in Croydon.

Request a Survey or call 020 3355 4944