Repairing the roof

Unfortunately, the roof is already in a worse condition than expected at this time.

Problems

There is water leaking through the existing bitumen shingles at different places. The leaks themselves are not very big but there are a lot of them. Th area in question is approximately 50m² (the lower 5m on the west-side of both buildings) which is maybe just some percent leaky in total.

The wood is mostly intact - there is 5-10 m² where it is hard to tell (above Staircase 20) and there are some pieces of wood that are not very good but don't look like they need exchanging.

Repairwork

Context: Long-term (2-5 years?) We need to redo all the rooftop material as bitumen shindles normally don't last longer than 10-20 years.

Options:

• Redoing all of the roof now
• Redoing the lower half of the west roof completely (50m² + somehow get it watertight with the existing material on the upper half)
• Fixing the leaks partially by putting/glueing/burning bitumen material on them (Material from BaDue or ~5€/m²)

Options 1 and 2 needs thinking about how we want to do it long term already now. Option 3 is just temporary patching. A combination of 2 and 3 would also allow us to gather experience: Redo the worst part, staircase 20, completely, while patching the rest.

Redoing options

EPDM foil

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