Insulate outer walls from the outside where you can
Outer walls are the second-largest source of heat loss; insulating them on the outside is the safer route, while inside insulation carries real risks of damp, mould and frost damage.
Do it yourself
Sources checked on .
Poorly insulated outer walls are the second-largest cause of heat loss in a home. If your walls have a cavity, filling it is a cheap first step, but it is usually not enough on its own to reach the 2050 target, so plan for outside or inside insulation as well. For that target, think of about 10 cm of PUR/PIR or 14 cm of mineral wool, EPS or XPS.
Insulating on the outside, behind new cladding or render, is technically the best option. Insulating on the inside keeps the facade as it is, but the wall stays colder and wetter. That raises the risk of condensation inside the wall, mould at junctions, frost damage to the bricks and rot in the ends of wooden beams.
Inside insulation is not suitable for frost-sensitive bricks, walls with glazed brick or another vapour-tight finish, walls that already show damp, or facades exposed to heavy rain. Never use it to hide a damp problem. Have a specialist choose the method, and fix damp first in every case.
Details
| Impact | Large · The Flemish government names poorly insulated outer walls the second-largest cause of heat loss in a home. How we rate impact |
|---|---|
| Estimated saving | Not quantified; the Flemish government calls poorly insulated outer walls the second-largest cause of heat loss in a home. (confidence: medium) |
| Who acts | You (owner) |
| Needs landlord's agreement | No |
| Type | Action |
| Constant or subject to change | Constant · Good practice that barely changes with new laws, prices or services. |
Do this together with
Sources
- Muurisolatie (in Dutch) · Woningpas (Vlaamse overheid) (official source) · checked on
- Binnenisolatie van buitenmuren (in Dutch) · WTCB and KU Leuven (research) · checked on