Damp façade? Look up before you have it insulated

A dark band on the outer wall, efflorescence or flaking paint: the reflex is to tackle the façade. That may be the right step — but not the first one, and the reason is sharply put.

Dutch consumer authority Milieu Centraal names leaking gutters, rising damp and lack of ventilation among the causes of moisture in an outer wall, and states that the cause must be remedied before you have façade insulation applied, otherwise it can even get worse. Insulation on a wet wall seals the moisture in rather than letting it out.

"Leaking gutters" is not listed first by accident. Water running over a full or tilted gutter, or dropping down the wall behind it at a poor junction, produces exactly the pattern that resembles rising damp: a vertical band, worse after rain, often on one side of the house. A blocked or cracked downpipe and a weathered junction at the roof edge belong in that list too.

So the order is: first establish where the water comes from, then the façade. What sits high up is rarely visible properly from the ground; a roof inspection (€ 150-350) assesses gutter, roof edge and junctions with photographs. If the roof edge or gutter does turn out to be the cause, that work falls under roof renovation (€ 3,500-12,500) or smaller repairs, depending on scope. Every guide rate is in the price index.