p4ingiv3r
2025-06-17 15:58:30
- #1
Hello and good day,
first of all, many thanks for your help in the form of this forum.
The following: old building renovation, complete renovation. Masonry brick or loose/unstable stone masonry. I have already gutted the entire building and now it’s about the new floor/ceiling structure.
From the ground floor to the 1st floor there is no problem, there I will realize the 180mm beams with intermediate ceiling insulation wood fiber 180mm. The problem is the 1st floor to the attic.
The attic remains unheated/cold. The attic is a "cold roof" with ventilation, so between the rafters there is no insulation and air can flow into the attic around the house at the masonry (bearing surface of the rafters on the masonry).
Since I have already bought the OSB boards for all ceilings, tongue and groove/slats as the top ceiling covering in the attic are unfortunately not possible.
The plan now from the 1st floor to the attic (from top to bottom) is
- OSB3 board 25mm EN300/13986:2004
- 180mm high ceiling beam
- 40-80mm air gap
- 140mm or 160mm wood fiber insulation SteicoFlex 036 between the beams
- vapor retarder with wall connection
- drywall
Since the insulation is only 140mm or 160mm thick, there is 40-20mm of air between the insulation and the OSB board so that condensing water can escape or air from outside can flow through.
There is then a circulation of air through the 40-20mm high air gap between OSB and insulation so that condensing water can dry. This gap runs continuously through the entire ceiling and goes outside.
I assume that my structure is correct according to logical thinking, since the top OSB board will probably act as a vapor barrier and thus I can prevent this problem with the vapor retarder below the insulation and the 40-20mm air gap above the insulation or this is the correct way? If I didn’t leave this air gap, then I would have a vapor retarder, the insulation and then the OSB board. The OSB board is in the worst case a vapor barrier and so all the condensate would accumulate there. That is why the 40-20mm air with connection to the outside (see picture).
From the ground floor to the 1st floor the structure will be floor covering with impact sound insulation - underfloor heating - 2x OSB 25mm - 180mm wood fiber insulation - drywall / naturally at the side wall with edge insulation strip:
- floor covering with impact/sound insulation
- underfloor heating
- 2x OSB3 board 25mm EN300/13986:2004 (with edge insulation strip up to floor covering)
- 180mm high ceiling beam
- 180mm wood fiber insulation SteicoFlex 036 between the beams
- drywall
Attached a photo of the structure to illustrate, it should be very clear.
Many thanks for your tips and help!
first of all, many thanks for your help in the form of this forum.
The following: old building renovation, complete renovation. Masonry brick or loose/unstable stone masonry. I have already gutted the entire building and now it’s about the new floor/ceiling structure.
From the ground floor to the 1st floor there is no problem, there I will realize the 180mm beams with intermediate ceiling insulation wood fiber 180mm. The problem is the 1st floor to the attic.
The attic remains unheated/cold. The attic is a "cold roof" with ventilation, so between the rafters there is no insulation and air can flow into the attic around the house at the masonry (bearing surface of the rafters on the masonry).
Since I have already bought the OSB boards for all ceilings, tongue and groove/slats as the top ceiling covering in the attic are unfortunately not possible.
The plan now from the 1st floor to the attic (from top to bottom) is
- OSB3 board 25mm EN300/13986:2004
- 180mm high ceiling beam
- 40-80mm air gap
- 140mm or 160mm wood fiber insulation SteicoFlex 036 between the beams
- vapor retarder with wall connection
- drywall
Since the insulation is only 140mm or 160mm thick, there is 40-20mm of air between the insulation and the OSB board so that condensing water can escape or air from outside can flow through.
There is then a circulation of air through the 40-20mm high air gap between OSB and insulation so that condensing water can dry. This gap runs continuously through the entire ceiling and goes outside.
I assume that my structure is correct according to logical thinking, since the top OSB board will probably act as a vapor barrier and thus I can prevent this problem with the vapor retarder below the insulation and the 40-20mm air gap above the insulation or this is the correct way? If I didn’t leave this air gap, then I would have a vapor retarder, the insulation and then the OSB board. The OSB board is in the worst case a vapor barrier and so all the condensate would accumulate there. That is why the 40-20mm air with connection to the outside (see picture).
From the ground floor to the 1st floor the structure will be floor covering with impact sound insulation - underfloor heating - 2x OSB 25mm - 180mm wood fiber insulation - drywall / naturally at the side wall with edge insulation strip:
- floor covering with impact/sound insulation
- underfloor heating
- 2x OSB3 board 25mm EN300/13986:2004 (with edge insulation strip up to floor covering)
- 180mm high ceiling beam
- 180mm wood fiber insulation SteicoFlex 036 between the beams
- drywall
Attached a photo of the structure to illustrate, it should be very clear.
Many thanks for your tips and help!