Facade renovation and insulation in Brussels, Flanders and Wallonia

Renovate or insulate your facade?

A dirty facade, eroded pointing or cracked render lets moisture into the walls. Cleaning, repointing or a new render is sometimes enough to put them right. But if you need scaffolding anyway, it is often the ideal time to insulate from the outside.

External wall insulation removes most thermal bridges, protects the masonry and does not reduce living space. It is the most effective solution for solid walls, common in Belgian houses built before the 1970s. It also improves summer comfort by limiting overheating of sun-facing walls.

External wall insulation techniques

The most common technique is to bond and fix insulation boards to the wall, then cover them with a reinforced render: this is the ETICS system. Another option is cladding, in timber, fibre cement or metal, fixed to a frame that holds the insulation and a ventilated air gap.

To reach a U-value of around 0.24 W/m²K, you generally need 12 to 16 cm of insulation depending on the material. Cavity walls can also be insulated by injecting insulation into the cavity, a quicker and cheaper technique, but less effective. The contractor first checks the width and condition of the cavity.

Planning permission, neighbours and grants

Changing the appearance of a facade visible from the street often requires planning permission, particularly in Brussels and in protected areas. The added thickness may also encroach on the pavement or affect a party wall: these points must be checked before signing a quote. The adviser flags them from the first conversation.

Grants for wall insulation depend on the region, the technique and your income, and set performance requirements. Your RhinoEnergy adviser calculates them with you and checks the conditions before work starts. They also tell you which documents to prepare, such as an energy audit where required, so you do not lose your entitlement.