Damp Proofing Islington

Islington has some of the finest Georgian and early Victorian streets in London. Barnsbury, Canonbury and the area around the Angel are full of terraces and squares built in the late eighteenth and early nineteenth centuries, while Highbury, Holloway and the streets north towards Archway are mostly later Victorian terraces, many now divided into flats.

Most of the borough sits on London Clay, with patches of gravel on higher ground. Clay holds water rather than letting it drain away, so ground moisture tends to sit against basement walls and under floors. The New River, still flowing in open sections through Canonbury, and the Regent's Canal running beneath the Angel in the Islington Tunnel are reminders of how much water moves through the area.

The classic Islington Georgian house has a lower ground floor set below street level behind a front lightwell, with brick vaults running out under the pavement that were once used for coal. These spaces were built to be damp and are now often used as kitchens, bedrooms and storage, which is where most of our basement work in Islington happens.

Pavement vaults are a particular problem. Water from the pavement above, leaking drains and the surrounding ground all find their way in, and the vault walls are usually unprotected brick. Making them dry enough to use normally needs a cavity drain membrane and drainage designed to BS 8102:2022, not a coat of tanking slurry that will blister.

Above ground, the walls are solid brick laid in lime mortar, finished in lime plaster and often stucco at the front. Modern cement render, cement pointing and gypsum plaster added over the years trap moisture in these walls, and much of the damp we see in Islington houses comes from materials that cannot breathe rather than from a failed damp proof course.

Large parts of Islington are conservation areas and many houses are listed. That affects how damp can be treated. We favour approaches that suit historic fabric, such as lime based plasters, repairs to rainwater goods and correcting ground levels, and we can provide the detail needed for listed building consent where work is required.

Parapet gutters and valley roofs hidden behind the front parapet are another common source of damp. When they block or the lining fails, water runs into the top of the walls and shows up as damp on upper floor ceilings and chimney breasts, sometimes a long way from the leak.

Front lightwells need attention as well. A blocked gully at the foot of the lightwell lets water pond against the lower ground floor wall and the door threshold, and it is one of the simplest problems to fix once found.

In the Victorian terraces further north and in converted flats across the borough, condensation and mould are common, particularly in basement flats and rooms with poor ventilation. We check humidity and ventilation as part of every survey so condensation is not mistaken for rising damp.

Because the right fix depends so much on the building, the survey comes first. Our CSSW and CSRT trained surveyors take moisture readings, use thermal imaging where it helps, and check drainage, pointing, ground levels and ventilation before recommending anything. You get a written report with photos that explains the cause in plain language and sets out the fix, with no obligation.

We cover N1, N5 and N7, including the Angel, Barnsbury, Canonbury, Highbury, Holloway and the streets towards Archway and King's Cross. Surveys are arranged from our London office at 45 Fitzroy Street.