Can you seal an eternit roof?
Eternit is found in many Danish garages, carports, outbuildings and older houses, and at some point the panels start to look tired. So the question arises: must the roof be torn off and replaced, or can it be saved? On most eternit roofs it can be saved, but there is one thing you must have clarified first.
This is how an eternit roof wears down
Eternit is fiber cement, and the surface becomes porous over the years. It happens slowly and for several reasons at once:
- UV breaks down the surface, so the sheets become rough and absorb water instead of directing it away.
- Moss and algae settle in the rough surface and retain moisture throughout the winter.
- Frost expands the water that has penetrated, and hairline cracks become real cracks.
- Joints, overlays and penetrations are where the leak starts, not in the middle of the slab.
An eternit roof rarely breaks with a bang. It just gets progressively more leaky until there is water somewhere you can't see.
Asbestos must be clarified before anything else
Older eternite sheets may contain asbestos and this changes the whole procedure. If you are in doubt about your roof, get it clarified before you touch it.
- The roof must be stable, clean and dry before application.
- If the roof contains asbestos, cleaning and preparation may only be carried out in accordance with applicable regulations.
- If in doubt, contact an authorized asbestos remover.
It is worth noting that a membrane works with and not against the problem here. It is laid on top and encapsulates the surface after proper preparation, instead of the sheets having to be broken up and driven away.
When the roof is ready
The work itself is the same as on roofing felt. The membrane is ready-mixed, applied with a roller or brush in one layer, and does not require a gas burner, welding or primer in several steps.
- Clean the roof thoroughly and let it dry completely, not just on the surface.
- Give overlays, edges and penetrations a go first. This is where the roof leaks.
- Roll the surface in one layer. The consumption is approximately 1.5 kg per m².
- The temperature must be above 5 degrees, and there must be dry weather throughout the drying period.
What you are left with
A seamless surface without joints, and that is the whole point of a roof where the problems were just in the overlays. The membrane is 100% waterproof, resistant from minus 40 to plus 90 degrees and has enhanced UV protection so that it does not become brittle again from the sun that wore down the old roof.
There is a 25-year product guarantee, and with correct application up to 40 years of life. The membrane is fire-classified Broof (t2) according to EN 13501-5 and CE-marked according to EN 1504-2, which is stated on the data sheet together with ETAG 005.
How much do you need?
A 20 kg bucket covers up to 13.3 m² in one layer. A garage roof of 40 m² therefore corresponds to 3 buckets. The membrane can be laid on eternit, roofing felt, concrete, slate, zinc, roofing foil, metal and wood, so it is rarely the substrate that is the problem.
See roof membrane for eternit roof and calculate your consumption
You can also go directly to liquid roof membrane and choose the color and number of buckets.
