Interior & roof insulation

Roof insulation

Roof insulation of the loft, the loft floor and the roof slopes, with a continuous vapour barrier and ventilation kept clear.

Request a quote 0497 74 99 32

The problem

Why it matters

In Belgium, 25 to 30 % of the heat lost from an uninsulated house goes out through the roof. But roof insulation fitted without a continuous vapour barrier and without an air gap simply moves the problem: the vapour condenses in the wool and the roof timbers take in water.

Quote: Priced after a site visit, free of charge and with no obligation.
Duration: 1 to 4 days depending on the surface area and the layout.
Area: 17 municipalities: Walloon Brabant, Brussels, Flemish Brabant and the province of Namur

How it runs

How we go about it

Every step exists for a reason. The ones that get skipped are exactly the ones that bring the problem back.

Site assessment
Available thicknesses, roofing underlay present or not, existing ventilation.
Preliminary treatment
Sound roof timbers before insulating. We never cover over attacked timber.
Fitting the insulation
Mineral wool between and under the rafters, or blown onto the loft floor.
Vapour barrier
Continuous membrane, overlapping strips, tape on every penetration.
Ventilation
Air gap kept under roof covering. That is what prevents condensation.

Included in the price

What the job covers

Survey and calculation of the thicknesses
Mineral wool or cellulose insulation
Continuous vapour barrier and tapes
Treatment of penetrations and openings
Keeping the air gap
Removal of offcuts

Frequently asked questions

Your questions

What thickness should you aim for?

For a roof slope, 22 to 30 cm in total depending on the product’s lambda. Below that, the gain does not pay for itself.

Loft floor or roof pitch?

If the loft is not lived in, insulating the floor costs less and heats less volume. If it is converted, it is the roof pitch.

And without roofing underlay?

There needs to be a ventilated air gap under the roof covering, or you fit an underlay. Without it, the insulation takes on water the first winter.

Are there any grants?

Depending on the Region and the period, yes, often tied to a minimum thickness and a registered installer. We tell you where to check rather than promising you an amount.

Cellulose or wool?

Blown cellulose for an uneven loft floor, board wool for a slope between rafters. Thermal lag is what counts in summer.

Do you lose ceiling height?

On a pitched slope yes, a few centimetres. We measure it beforehand so you can decide knowing the facts.

By municipality