Why Damp Repair Costs Vary So Widely in London
Damp is one of the most common issues in London homes — and one of the most misunderstood when it comes to cost. Whether you're dealing with peeling paint, black mould, or crumbling plaster, the price to fix it can vary from £500 to well over £5,000, depending on the cause and severity.
The biggest mistake homeowners and landlords make is guessing what type of damp they have and jumping straight to treatment. In reality, each type of damp requires a different approach — and choosing the wrong fix not only wastes money but can actually make the problem worse.
That’s why the first step is always a professional damp survey.
The Three Types of Damp — and Their Repair Costs
Every damp issue falls into one of three categories. Here’s a breakdown of what each one typically costs to fix in London.
1. Rising Damp: £1,000 – £4,000+
What it is: Rising damp occurs when moisture from the ground rises up through the walls. This is particularly common in older homes across London where the original damp-proof course (DPC) has failed — especially in Victorian terraces in areas like Camden, Peckham, or Islington.
Signs:
Tide marks on walls
Crumbling plaster near skirting boards
White salt deposits on wall surfaces
Typical Repair Costs:
Installing a chemical DPC: £1,000 – £2,500
Replastering internal walls: £500 – £1,500
Skirting board and timber replacement: £500+
Key note: These prices can rise significantly if large wall areas are affected or if multiple rooms are involved.
2. Penetrating Damp: £500 – £3,000+
What it is: Penetrating damp is caused by water getting in from the outside — usually due to faulty brickwork, damaged render, leaking roofs, or blocked gutters. This type of damp can affect any level of the property.
Signs:
Damp patches that worsen after rain
Localised mould growth
Peeling paint or staining on ceilings and upper walls
Typical Repair Costs:
External brick repointing: £750 – £2,000
Gutter/roof repair: £500 – £1,200
Internal plaster and decoration: £500 – £1,000
Important: Treating penetrating damp without fixing the source (e.g. cracked brickwork) will only offer temporary relief.
3. Condensation Damp: £250 – £1,000+
What it is: Condensation is caused by warm, humid air hitting cold surfaces — typically due to poor ventilation or insufficient heating. It’s the most common form of damp in modern flats and poorly ventilated homes across London.
Signs:
Black mould in corners or around windows
Condensation on glass and walls
Musty smells
Typical Repair Costs:
Installing an extractor fan: £250 – £500
Improving insulation or ventilation systems: £500 – £1,000+
Mould treatment and redecoration: £250 – £750
Note: Without proper diagnosis, some homeowners mistake rising or penetrating damp for condensation — which can lead to ineffective solutions.
Why You Need a Damp Survey Before Spending a Penny
At first glance, it can be hard to tell one type of damp from another. But misdiagnosis leads to wasted money and recurring issues.
That’s why the only reliable way to budget for damp repairs is to start with a professional damp survey.
Our damp survey includes:
Moisture meter readings and humidity checks
Thermal imaging to identify hidden damp zones
Assessment of walls, ventilation, insulation, and brickwork
Diagnosis of rising, penetrating or condensation damp
A written report with expert findings and recommended actions
We charge for our damp surveys because they require on-site investigation, equipment, and a thorough written report that takes three hours on average to prepare. Our surveys have uncovered issues missed by even £3,000 HomeBuyers Reports — saving clients from costly surprises later.
Why London Damp Repairs Cost More Than You Think
Repair costs in London tend to be higher due to:
Older building stock (many without modern damp-proofing)
Labour and access costs in central locations
Difficulty diagnosing complex structural damp in converted or extended homes
The need for coordinated internal and external repair work
For example, fixing rising damp in a basement flat in Hackney may involve structural tanking and ventilation upgrades, whereas resolving penetrating damp in a Southwark terrace might require scaffold access and brick repair.
Get a Clear, Accurate Damp Diagnosis — Book Your Survey Today
Whether you’re budgeting for property repairs or trying to resolve a tenant complaint, don’t guess the cost — know the cause.
We offer expert damp surveys across London, helping homeowners, landlords, and property managers avoid unnecessary work and focus only on what’s needed.