Mould Removal: Costs, Causes and Fixes
Black mould shows up in a lot of UK homes once the weather turns cold. Cleaning it off is the easy part. To stop it coming back you need to know where the moisture is coming from, and whether the fix is a better fan, a bit of heating or a repair to the building.
Quick answer
How much does mould removal cost?
Professional treatment for one room usually costs £200 to £500, with £300 typical in October 2026. A whole three-bedroom house costs £750 to £1,500. A replacement extractor fan costs £100 to £250 fitted and a loft PIV unit £500 to £1,000.
Read the full mould removal cost guide →Where the moisture comes from
Condensation
The most common cause. Steam from cooking, showers and drying clothes settles on cold walls and windows, and black spots appear in corners, around window frames and behind furniture. It gets worse from October onwards, when windows stay shut and the heating goes on and off.
Fans, PIV units and dehumidifiers: prices →Leaks and penetrating damp
Water getting in from outside through blocked gutters, failed pointing, cracked render or a damaged roof. The patches spread after heavy rain and the wall feels wet, not just steamy.
Guttering costs →Rising damp
Ground moisture creeping up a wall, leaving a tide mark up to about a metre high and crumbling plaster near the skirting. It is diagnosed far more often than it really happens, so get an independent opinion before paying for treatment.
Rising damp treatment costs →Clean it yourself or call someone?
A few spots on a window reveal or sealant line are fine to tackle with a mould spray, gloves and eye protection. Call a specialist if the mould covers large areas, is in the loft or behind fitted furniture, comes back within weeks, or someone at home has asthma, a lung condition or a weak immune system. Government health guidance on damp and mould explains who is most at risk.
Renting?
Damp and mould caused by the building are your landlord's responsibility. Council and housing association landlords in England have had fixed deadlines to investigate and fix damp and mould since Awaab's Law came in on 27 October 2025. The government is consulting on extending it to private renting. Our cost guide sets out what landlords must do and how to report it.
Mould and damp guides
Mould removal cost guide
Prices by room and for a whole house, condensation fixes, surveys and landlord rules.
Damp proofing cost guide
Injection DPCs, tanking and penetrating damp repairs.
Damp proofing guide
How to tell rising damp, penetrating damp and condensation apart.
Cavity wall insulation cost
Warmer walls attract less condensation.
Get at least three quotes
Prices for the same room can vary by a couple of hundred pounds, and firms don't all include the same things. Ask three to quote for the same job, check whether redecoration and a survey are included, and ask each one to explain in writing what is causing the mould. Members of the Property Care Association work to the trade body's standards.
Free, with no obligation to book.
Written by Chris Kervin, Co-Founder, Less.co.uk
Last updated: · Methodology