Roof & roof covering

Laying flat-roof waterproofing on a flat roof

Multi-layer bituminous waterproofing on a flat roof: garage, annexe, extension, non-accessible terrace.

The problem

Why it matters

A flat roof almost never leaks in the middle. It leaks at the upstands, at the corners and around the roof outlet — where the old membrane was badly turned up or has ended up shrinking back.

Quote: Priced after a site visit, free of charge and with no obligation.
Duration: 1 to 3 days for a standard surface.
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.

Probing
We check what is under the membrane. Waterlogged insulation gets replaced, not covered over.
Removal or overlay
Depending on the condition, full removal or fitting over the existing layer if the substrate allows.
Vapour barrier and insulation
If the roof is insulated, PIR or wool depending on the configuration.
Undercoat
First layer, self-adhesive or torched, with staggered joints.
Finish
Top membrane torched on, mineral-finished or smooth depending on exposure.
Measurements and waste removal
Upstands round the perimeter, outlet spigot, water test verified.

Included in the price

What the job covers

Survey of what is there
Removal and disposal if needed
Vapour barrier and insulation to suit the configuration
Two-layer torched waterproofing
Upstands, flashings and edge trims
Roof outlet and overflow checked

Frequently asked questions

Your questions

How long does flat-roof waterproofing last?

A two-layer system laid properly lasts 20 to 25 years. A single layer laid in a hurry lasts a lot less.

Can you lay over the old flat-roof waterproofing?

If the surface is dry and sound, yes. If the insulation is waterlogged, no: the problem would come back from underneath.

Can you walk on it afterwards?

Occasionally, for maintenance. For a walk-on terrace you need protection: slabs on pedestals or ballast.

Is the blowtorch a risk to the house?

On upstands and close to timber we work with self-adhesive or hot air. The torch is only used where it is safe.

What if water stands on the roof?

A residual puddle is acceptable. Permanent standing water points to a wrong fall or a badly placed roof outlet: that gets corrected when the roof is redone.

Do you attend leaks as an emergency?

Yes, a temporary repair first to stop the water, then costing the permanent repair calmly.

By municipality