However, this occurs in older buildings. In some cases, bitumen sheets were also used. Simply omitting the ventilation could lead to moisture problems.
Yes okay, I just meant to have read that you should not completely fill the rafter depth in order to avoid direct contact of the insulation with the vapor barrier.
How is that supposed to work? Gravity causes the insulation to rest on the membrane anyway.
How is that supposed to work? Gravity causes the insulation to rest on the membrane.
Valid objection. Surely the underlay above the insulation is meant and not the vapor barrier below. If ventilation of the insulation wool, then between the underlay and the insulation wool as partial rafter insulation or full rafter insulation without an air layer.
No, it was actually the vapor barrier that was meant. So when I think of insulation between rafters, it is clamped between the rafters. It should hold there by itself and not be "held" by the vapor barrier.... And I have not planned an additional layer "behind the insulation" towards the attic.... what would that be good for?
No, it was actually the vapor barrier meant. So when I think of insulation between rafters, it is clamped between the rafters. It should then hold by itself there and not be "held" by the vapor barrier....
And I did not plan another layer "behind the insulation" towards the attic.... what would that be good for?
Well, that is pointless. You are foregoing ventilation of the insulation layer without making full use of it. So either with an air layer between the insulation wool and the underlay membrane or not at all.
Another layer towards the attic is the insulation below the rafters. This is used to insulate the area of the counter-battens for the drywall panels again if the rafter depth is insufficient. This also insulates the rafters themselves. They are often a thermal bridge when they extend all the way to the outside.
Viewed from the inside: 2x counter battens Battens Vapor barrier (climate membrane) Insulation Underlay battens or sheathing if applicable, ventilation via counter battens Roof covering the insulation is responsible for the U-value the membranes for the Sd-value the air space towards the interior can serve as a "pre-wall installation layer".
