Rising Damp Treatment in an End Terrace House, Desborough NN14
A basement that had never been waterproofed was quietly feeding moisture straight up into the ground floor walls of this Union Street terrace. Here’s how the survey traced it back to source, and what it took to put it right.
Project at a Glance
The Brief
The client got in touch about a Victorian-era end terrace on Union Street, Desborough, wanting a full picture of what was going on with damp in the property before deciding on next steps. Our surveyor, Matt Ashdown, went out to carry out a complete inspection, working through the external elevations, the roof void, the living spaces and the basement, using moisture meter readings and thermal imaging alongside the usual visual checks.
It’s a good example of why we always survey a property as a whole rather than just the room someone’s worried about. The damp showing on the living room wall here wasn’t really a living room problem at all.
What the Survey Found
The basement was the standout issue. Moisture readings were high throughout, including within the floor itself, and there was visible damage to the plasterboard and mould growth. It hadn’t been effectively waterproofed at any point.
In the gas meter cupboard, someone had fitted insulation directly against damp brickwork with nothing more than a thin sheet of plastic between the two before boarding it over, which had unsurprisingly done nothing to stop moisture getting through.
When a small section of the basement floor was lifted for testing, the readings underneath were just as high, with no sign of any damp-proof membrane. Humidity in the space was recorded at 79% on the day.
Directly above, the living and dining rooms were showing high moisture readings and damaged plaster at low level. Given what was happening in the basement below, this had all the hallmarks of moisture travelling upward through the masonry by capillary action rather than a separate, unrelated problem. The thermal imaging supported that read, picking up cold banding at low level in exactly the spots where the meter readings were highest.
A handful of other things were noted while Matt was there, worth flagging even though they weren’t the main event. Staining and raised timber moisture around the chimney stack pointed to tired flashing. An extractor fan was not installed in the bathroom, and there were no trickle vents in the upstairs rooms at all, leaving the north-facing front room vulnerable to condensation and peeling wallpaper. The exterior had an old damp-proof course injection that seemed to be decades old; the side wall had missing brickwork; the downpipe from the porch was letting the water drain directly to the ground; the gutters were overgrown with vegetation; the basement’s coal chute was practically without any ventilation at all.
The Treatment Plan
Because the basement was clearly the source, the plan focused on the ground floor walls rather than just skimming over the surface damage. The affected plaster in the living and dining rooms was to come off up to 1.2m, matched to the areas marked on Matt’s floor plan, followed by a new chemical damp-proof course injected along the wall base. From there, the walls would be finished in a waterproof render and re-plastered, giving the residual salts somewhere to sit without ruining the new decoration.
Longer term, a cavity drain system with a sump pump was recommended for the basement itself, since re-plastering the rooms above only deals with the damage already done, not the wet basement causing it. The external items, brickwork repairs, re-routing the downpipe, clearing the gutters, a roofer looking at the flashing and improving ventilation to the coal chute, were left as separate recommendations for the client to arrange in her own time.
The Work Carried Out
Carl Shoreman spent 5 days on site carrying out the rising damp treatment hacking off the affected plaster, injecting the new chemical DPC, and re-rendering and setting the walls ready for redecorating. Nothing unexpected came up during the works, and the job stuck to the agreed scope without any variations.
The Result
The job was completed and signed off on 27th March 2026. The client was on site for the handover, was walked around by Carl to see the finished work, confirmed everything matched what had been agreed, and signed off happily, saying she’d recommend us.
Rising damp like this rarely has just one cause worth treating. Sorting the plaster and DPC on the ground floor deals with the moisture that’s already worked its way into the wall, but the basement recommendation is the part that stops it coming back. Do one without the other, and you’re really just buying time.
Rising Damp FAQs
What causes rising damp in a house like this?
Rising damp is moisture drawn upward through masonry by capillary action, usually because the damp-proof course has failed, was never fitted properly, or because moisture is getting in from below, such as from a wet, unwaterproofed basement or void.
What does a chemical damp-proof course injection involve?
Holes are drilled along the base of the affected wall and injected with a water-repellent chemical DPC, forming a barrier within the brickwork. The wall is then usually re-plastered with a waterproof render so any salts left in the masonry can dry out without spoiling the new finish.
Why remove plaster up to 1.2m rather than just at skirting height?
Rising damp and the salts that come with it can sit well above the visible tide mark on a wall. Taking the plaster off to a set height, rather than patching the worst-looking bit, gives a result that’s far more likely to last.
Does rising damp originate from a basement?
Yes. Dampness originating from a basement or cellar that lacks waterproofing measures will find its way to the upper floors through the masonry structure, causing rising damp at ground level, although it originated underground.
Do you offer your services for Northamptonshire in regards to damp surveys and rising damp treatments?
Yes. We undertake damp surveys, rising damp treatment and basement waterproofing throughout Northamptonshire and the rest of the Midlands.
Damp proofing or basement dampness problem?
Our qualified surveyors diagnose the real cause and give you a fixed-price quote. The survey fee is deducted from the cost of work if you go ahead.
Survey carried out by Michael Young, waterproofing surveyor at Advanced Damp. Project completed in Fulham, SW6.
Sam Fitzgerald is the founder of Advanced Damp and a working damp and structural waterproofing surveyor with over 12 years of experience diagnosing and treating moisture problems in residential and commercial properties across London and the South East. He is FODCS certified (a Federation of Damp Certified Surveyor) and a member of the Federation of Damp. His hands-on work covers rising damp, penetrating damp, condensation, basement waterproofing to BS 8102, and thermal imaging surveys, and he has personally completed over 400 damp surveys across properties of every type and age. Everything he writes draws directly from jobs he has carried out. He does not write about treatments, products or causes he has not dealt with first-hand in the field.
