Unfortunately, the roof is already in a worse condition than expected at this time.
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EPDM foil is a very weather resistant, synthetic, recycleable material. It is said to last 20-50 years, depending on quality of work. It needs to be glued on a surface and is normally used for flat roofs. It costs about 15€/m² but maybe we can get it second hand as well. The glue costs another 3€/m² and the polymerisation tape to connect two sides of the foil is 6€/m.
It sounds like theoretically we could just add this as another layer but it is important that the surface underneath is very clean so the glue works. Maybe the current shindles should then be better removed.
Bitumic roof
The roof can be redone similar to how it is done now. "Dachpappe" or "Schweißbahn" is the general term for this. There is the possibility that we just add another layer on top of the existing roof, otherwise we would need to build two layers. A gas burner is used to heat the new bitumen so it connects and seals to the lower layer. The top layer needs to have an UV protective layer as well, schist is used for that.
A good top layer would be PYE PV 200 S 5 for approx. 5-6€/m² that could be put on our existing roof.
Comparison of work
| EPDM | Bitumen | |
|---|---|---|
| removal of current roof | recommended | optional |
| tools | brush for glue, scissors, lots of glue | gas burner, gas, knife/scissors |
| ease of work | available in any size, but connection expensive. Easy to glue on correctly | 5m x 1m, needs some experience burning it correctly |
| cost | ~20-25€/m² in total | ~8€/m² in total |