Rising Damp Treatment Costs by Scope
Costs below are for chemical DPC injection plus replastering. They assume standard brick construction and do not include redecoration.
| Scope | What Is Included | Typical Cost Range |
|---|---|---|
| Single wall — DPC injection only | Chemical injection to one external wall (up to 5m) | £300-£600 |
| Single wall — DPC injection + replaster | Injection plus salt-retardant replastering of internal face | £700-£1,600 |
| Mid-terrace/semi — ground floor walls | All ground floor external walls, injection + replaster | £2,500-£5,000 |
| Detached house — full ground floor | All external walls + internal party wall (if affected) | £4,000-£8,000 |
| DPC injection only (whole house, no replaster) | Injection works only — replaster quoted separately | £1,500-£3,500 |
| Rising damp survey (PCA-member specialist) | Full diagnosis report with moisture readings | £150-£350 |
| Independent RICS damp survey | Second-opinion survey from RICS surveyor | £200-£400 |
2026 UK averages. London and South East 15-25% higher. Always get three quotes from PCA-member companies.
What Causes Rising Damp?
Rising damp occurs when groundwater is drawn upward through the porous structure of a wall by capillary action — the same force that draws water up a paper towel. It is held in check in most buildings by a damp-proof course (DPC): a horizontal impermeable layer installed at the base of a wall, typically at least 150mm above external ground level.
The most common causes of genuine rising damp are: a failed or absent DPC (common in pre-1920 properties built before DPCs were standard); a bridged DPC, where soil, render, paving or an extension has been built up above the DPC level; or a DPC that has been physically breached during building work.
Critically, many cases diagnosed as rising damp are actually penetrating damp (water ingress through walls, roof or windows) or condensation (moisture in warm air depositing on cold surfaces). A 2013 RICS report estimated that genuine rising damp is significantly over-diagnosed — often because the surveyor has a commercial interest in selling treatment. An independent moisture analysis is strongly recommended before spending money on treatment.
How Rising Damp Is Treated
A proper remediation follows a defined sequence — chemical injection alone, without replastering, will not resolve the visible damage.
Independent diagnosis
A PCA-accredited surveyor uses a calibrated moisture meter, hygrometer and, ideally, carbide bomb testing or lab analysis of wall samples to confirm genuine rising damp rather than condensation or penetrating damp. Cost: £150-£350.
Identify and resolve bridging
Before injecting a new DPC, any bridging (render, soil, paving or planting beds built up above the existing DPC) must be removed. If bridging is the sole cause, removing it may resolve the problem without injection.
DPC injection
Holes are drilled at regular intervals (typically every 120mm) along the mortar course at the base of the wall. A low-pressure silicone or cream-based chemical is injected into each hole, where it diffuses through the masonry to form a new water-repellent barrier. The holes are then pointed.
Salt-retardant replastering
The existing plaster is removed to a minimum height of 1m (or higher if damp has risen further). A salt-retardant backing render — typically containing hydraulic lime or a proprietary renovation plaster — is applied. This is essential because the existing plaster will be saturated with hygroscopic salts that will cause ongoing visible damp patches even after the DPC is installed.
Allow to dry and redecorate
New plaster must be allowed to dry fully — a minimum of 4-6 weeks is typical — before final decoration. Breathable paint should be used on treated walls to allow any residual moisture to continue evaporating.
What Affects the Cost of Rising Damp Treatment?
The final bill depends on several variables beyond simple wall length:
- Wall thickness: Solid brick walls (9 inches / 215mm+) require more chemical and longer injection times than modern cavity walls.
- Height of damp: If moisture has risen more than 1m up a wall, a larger area of plaster must be replaced, increasing materials and labour cost significantly.
- Number of walls affected: Treatment is priced per wall run. A full four-wall ground floor on a detached house costs considerably more than two walls of a terrace.
- Internal vs external access: Furniture removal, floor covering protection and access to the wall base all add time to the job.
- Salt contamination level: Heavily contaminated walls may need two coats of salt-retardant render, increasing materials cost.
- Guarantee requirements: Reputable companies offer 20-30 year guarantees on injection work. These guarantees are tied to the contractor — check they are backed by an insurance-backed guarantee (IBG) in case the company ceases trading.
- Location: London and South East rates run 15-25% above the national average.
Pitfall: Conflicting Surveys from Contractors
Be extremely cautious of a free survey offered by a remediation company — they have a commercial incentive to diagnose rising damp. The Property Care Association (PCA) recommends obtaining an independent survey from a RICS-accredited surveyor or a PCA-member surveyor who charges for the diagnosis separately from any treatment. The cost of a proper survey (£150-£400) is money well spent before committing to thousands of pounds of remediation work.
Flag It Before You Buy
Our planner helps you set a realistic refurbishment reserve before you buy — if a pre-purchase survey flags possible rising damp, use our tool to model the remediation cost alongside your other planned works so you can make an informed offer.