Damp by a Lower Ground Stairwell on Bromfield Street, Islington N1
Advanced Damp had already treated part of this house on Bromfield Street in Islington. The owner called us back when a new damp patch appeared in a separate area around the stairwell leading from the lower ground floor.
Project at a Glance
The Brief
The damp patch was in an area that had been dry at the time of the original survey, so it had not needed treatment then. The owner wanted to know what had changed.
The Survey
Inside, the wall around the lower ground stairwell showed low level damp staining, surface breakdown and a tide mark pattern, with elevated moisture readings at low level. The plaster also appeared soft and lightweight, which may have been adding to the breakdown.
Outside, the surveyor recorded high ground levels, hardstanding and restricted drainage at the rear close to the affected wall. These were likely to be holding moisture against the lower ground walls. As the report notes, moisture can move and conditions can change over time, especially in lower ground and basement areas.
The Solution
A localised repair, clearly scoped:
- Treat the areas marked on the floor plan with a damp proof membrane system and new finishes.
- Set out the external drainage and ground level issues for the owner to address.
- Make clear which areas the new work covers, so retained areas such as the stairs and cupboard are understood.
The Work
The membrane work was completed in a day on 8 July 2026.
The Result
The owner had a clear explanation of why damp had appeared in a new place, and a repair matched to it. Lower ground floors in Islington and Barnsbury often sit against high ground and paving at the rear. Read more about basement waterproofing in London or see our north London damp proofing page.
Frequently Asked Questions
Why has damp appeared somewhere new after treatment?
Moisture can move to untreated areas over time, especially in lower ground floors. Changes outside, like raised paving or blocked drainage, can also shift where water collects.
What is a damp proof membrane?
It is a studded or sheet membrane fixed to the wall that keeps moisture in the masonry away from the new finish, often used below ground.
Does high ground outside cause basement damp?
It can. Ground and paving above internal floor level hold moisture against the wall, and poor drainage makes it worse.
Damp in a lower ground floor?
Our CSSW and CSRT trained surveyors find the real cause before recommending any work. Non-invasive survey with a clear written report. No obligation.
Survey carried out by Chris Baxter at Advanced Damp. Project completed in Islington, N1.
Sam Fitzgerald is the founder of Advanced Damp and a working damp and structural waterproofing surveyor 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.
