Damp Surveys & Diagnosis
Correctly identifying which of the three damp types is actually present is the single most important step before any treatment starts, since the wrong treatment doesn't just fail to fix the problem, it can actively make it worse — sealing a wall that needs to breathe, for instance, traps moisture rather than releasing it. A proper survey uses a moisture meter alongside a visual inspection, checking the pattern and height of damp, and considering the property's construction and ventilation rather than relying on a single reading in isolation.
Insulation: Cavity Wall & Loft
Cavity wall insulation fills the gap between a property's inner and outer wall layers, improving thermal performance considerably in properties built with a cavity — mostly post-1920s construction, since solid-wall Victorian and Edwardian properties don't have a cavity to fill and need a different insulation approach entirely. Loft insulation is usually the more straightforward and cost-effective upgrade, laid between and over ceiling joists, and it's often installed alongside other loft work — a conversion, or simply topping up thin or degraded existing insulation that's lost much of its effectiveness over decades.
Timber Treatment
Damp and timber decay are closely linked — sustained moisture is what allows wet rot and dry rot to take hold in structural timber, and woodworm infestations are more likely to establish in damp, untreated wood than dry, well-ventilated timber. Treating the underlying damp is usually the first step, since treating timber decay without addressing the moisture causing it means the problem returns. Where genuine structural timber damage has occurred, affected sections need replacing rather than just treating, with the replacement timber itself treated to prevent recurrence.
Ventilation in London Flats
Poorly ventilated flats, particularly conversions where original ventilation paths have been altered or blocked off during previous renovation work, see condensation problems at a higher rate than houses with more natural airflow. Extractor fans in kitchens and bathrooms need to actually vent outside rather than into a loft void or a neighbouring space, and trickle vents in window frames — often taped shut or painted over by a previous occupant trying to reduce draughts — need to stay open to do the job they're designed for. A flat that seems to have a persistent, unexplained mould problem often has a ventilation issue that's easy to miss without specifically checking for it.