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Cavity wall, roof and floor insulation in the Netherlands: which first?

Updated 2026-09-15 · Netzy B.V., Eindhoven

In most Dutch houses built between roughly 1930 and 1990 the biggest, cheapest gains are cavity wall insulation, roof insulation and floor insulation from the crawl space. Insulating the shell first means a smaller, cheaper heat pump later. The ISDE subsidy applies per square metre when you combine at least two insulation measures, or insulation with a heat pump.

Attic floor is not the same as the roof

Insulating the attic floor and insulating the pitched roof are two different measures. One does not prove or replace the other, and the effect on the label differs. We assess them separately.

Glazing comes later

Replacing double glazing is rarely the first step. Per euro, the roof, cavity wall and floor usually save more. Glass makes sense when frames need replacing anyway.

How Netzy tells you in advance what is technically feasible

Before anyone visits, we measure the roof, facade and floor areas of your specific house from the national 3D building model and public registers (BAG, EP-Online). From those areas we calculate the heat demand and, per measure, what it does to the label.

Every assumption gets a certainty percentage and a source. If a key fact is missing (year of construction, floor area or house type), we give no advice rather than filling in an average.

The order is fixed: insulate the building shell first, then install. Ventilation is decided together with the insulation, because once ducts are closed off, heat recovery ventilation is usually no longer possible.

Frequently asked questions

Is ISDE subsidy available to expats?

Yes, ISDE is for owner-occupiers of a house in the Netherlands, regardless of nationality. You apply at RVO after the work, with the invoice stating the registered product codes.

Does insulation cause damp problems?

Insulation changes how moisture moves, so ventilation is decided together with the insulation. That is part of our standard check.

Netzy calculates what is technically feasible and what it costs, and explains the schemes. We do not give mortgage advice and do not broker mortgages. What you personally can borrow, and at what rate, is assessed by a mortgage adviser or lender. Label outcomes are route indications, never a guarantee.
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