Damp proofingin Brentcause first, then cure

Where the survey confirms a failed or missing damp proof course, we inject a new chemical DPC into the mortar bed using an accredited Sovereign or Wykamol system, strip the salt-contaminated plaster and replace it with a salt-retardant render and skim finish.

Both stages are essential. Hygroscopic salts left in the original plaster keep pulling moisture out of the air, so the wall still looks and feels damp even when the rise itself has been stopped.

First, though, we check for bridging, raised paving, render carried past the DPC, rubble in the cavity, because in Brent that is frequently the real cause, and correcting it is usually a much smaller job.

In converted flats and HMOs, black spotted mould in corners, on window reveals and behind furniture is almost always condensation. It appears on cold surfaces, is worst in winter, affects kitchens and bathrooms first, and does not produce the salt bands you see with rising damp.

Treating that with an injected DPC achieves nothing. The answer is managing moisture and improving air movement, effective extraction where moisture is generated, adequate background ventilation, and addressing cold bridging at the worst spots.

We will tell you that at survey, in writing, even though it means a smaller job for us. For landlords and agents that written diagnosis is useful evidence when discussing the issue with tenants.

Damp that worsens with rain is water crossing the external envelope. On Brent's stock the usual sources are eroded mortar joints, cracked or debonded render, defective sills, perished sealant at windows, and gutters or downpipes soaking a narrow band of wall.

We repoint in a mortar compatible with soft London stock brick, repair or renew render, replace spalled bricks, reinstate drip details and correct rainwater goods. Where cracking has opened a route for water, helical brick stitching restores the masonry.

Older Brent terraces often have cellars that are now being used as storage, utilities or habitable rooms. Making one dry means structural waterproofing designed for water under pressure: cementitious tanking bonded to sound masonry, or a cavity drain membrane with perimeter drainage and a sump and pump where required.

Junctions, penetrations and returns are detailed as part of the accredited system, because that is where these installations leak. Waterproof paint will not hold back groundwater.

Alongside Brent we cover Harrow and the Middlesex towns, West London, the wider London boroughs, Watford, Slough, Buckinghamshire, High Wycombe and Surrey.

Calls are taken Monday to Friday 8am to 8pm and Saturday 8am to 1pm, with evening surveys available for people who work full time or need occupant access arranged.