References to the dark blue trivialities marketplace are not welcome here - therefore I do not mention its name. But since today there is a group with my name where one can get in touch from builder to builder. Then it doesn’t matter if the PM troubleshooting remains a test of patience.
I have another concern regarding the roof. We want to award the contract soon, and there are differences in the execution variants from 3 providers. The following structure is always the same, from bottom to top:
Tax advisor ceiling: 200 mm
PUR-WLG 023: 160 mm (possibly 2 x 80 mm laid crosswise)
Rafters 8/20 KVH C-24
(Gable walls are masonry)
The roof space is thus designed as a cold roof and ventilated via perforated sheets.
The following variants are offered by 3 roofers with double standing seam technology in titanium zinc or aluminum from the rafters upwards:
Variant 1:
Underlay membrane
Counter battens
Battening
Roof sheathing made of softwood 24 mm
Structured separating layer (Delta Trela)
Metal roofing
Variant 2:
Underlay membrane
Counter battens
Battening
Roof sheathing made of softwood 24 mm
Nonwoven (Rheinzink)
Metal roofing
Variant 3:
Roof sheathing made of softwood 24 mm
Breathable Tyvek membrane with laminated mesh channels
Metal roofing
In variant 3, the underlay membrane and battens are omitted and the sheathing is attached directly to the rafters. However, it is still the most expensive offer. Because the price per square meter for the metal alone is staggering.
So now the question arises who is actually right. Can the underlay membrane be omitted? What do you think about the roof builds? Especially the insulation, which will be installed by ourselves.
In general, in my opinion, it is always a ventilated roof through the structured separating layer with the knobs?