Hello!
I have water problems I plan to solve by extending the basement under the porch (instead of raising the house by 20cm).
I am considering how the ceiling (the floor under the porch) can be maximally insulated (preferably no thicker than 30cm with floor/planks or similar). The extension would be about 3m out from the house wall (with the porch on top).
1a) Insulation material (important)
Maybe there is a ready-made "sandwich" construction with good/better insulation value and its own load-bearing capacity?
or is Cellplast still the best?
or...
1b) Thermal conductivity
What U- or λ-value can be expected with the above construction?
2) Load-bearing capacity - load possibly greatest from own weight and possibly snow load.
If the solution is roof trusses/floor joists (which are the same in this case)
What dimension should be sufficient?
What spacing should these be placed at?
3) Roof pitch - for water drainage and material
What slope is recommended (is 1° enough)?
From what I understand, roofing felt can be used with a small roof slope.
EPDM rubber can also be an option.
