Roof membrane: how to choose the best one (5 things to check)
There are now many floating roof membranes on the Danish market, and they look alike on the shelf. The difference only becomes apparent after a few winters. Here are the five things you should look for before choosing, and how Luna Roof stacks up on each of them.
1. Elasticity: can the membrane follow the roof?
A roof works. It expands in summer heat and contracts in frost, and the substrate moves with it. A membrane that cannot stretch will crack instead.
Look for the elasticity in percentage and keep the number up against Luna Roofs up to 300%. The more the membrane can stretch, the better it bridges cracks in the substrate instead of breaking over them.
2. Seamless or with joints?
Almost all leaks start in the same place: in a joint. In the case of roofing felt, it is the overlays, in the case of sheets, it is the screw holes and the coverings.
A liquid membrane is applied as a liquid and hardens into one continuous surface. There are no joins because there are no edges to join. This is the single biggest difference between liquid membrane and traditional roofing felt.
3. Lifetime and warranty are not the same
Many manufacturers state an expected lifespan, but far fewer sign a warranty. Always ask what is actually covered and for how long.
Luna Roof has an expected lifespan of up to 40 years and a 25-year product warranty. The warranty is on the product, not just that the bucket was full when you opened it.
4. Temperature range
A flat roof in Denmark must be able to withstand both frost in winter and a sunny summer day with black coating, without the membrane becoming brittle or sticky.
Luna Roof is tested from -40 °C to +90 °C. That number is the operating temperature, i.e. what the membrane can withstand year after year when it is hardened.
5. Can you apply it yourself?
This is often the real price difference. If the membrane requires a gas burner, multi-step primer or licensed installer, the labor costs end up costing more than the material.
Luna Roof is 1-component and ready-mixed. It is applied by roller or brush, and one coat is enough. 20 kg covers up to 13.3 m², i.e. approx. 1.5 kg per m².
How to calculate the price
Always compare per square meter, not per bucket. The buckets have different sizes and different consumption, so the price per liter means nothing on its own.
The calculation is: price per bucket divided by the number of m² the bucket covers. On our product pages, you can enter the size of the roof and get the number of buckets immediately.
How about a brand new roof?
A full roof replacement costs many times that of a seal, when demolition, disposal and labor costs are included. Sealing with membrane can be done in a few days without tearing anything down.
The prerequisite is that the existing construction is sound. If there is rot in the rafters or water in the insulation, this must be fixed first. Membrane solves the leak, not moisture damage that is already in the construction.
Briefly summarized
- The elasticity is stated as a percentage, and the higher the better
- Seamless surface without overlay
- Written product warranty, not just an expected lifetime
- Temperature range covering Danish winter and summer
- Applying you can manage yourself if you want to save the labor salary
See floating roof membrane from Luna Roof, and calculate how many buckets your roof will need.
