Hello everyone,
we have purchased a house from the early 1980s (solid construction, the roof is still in very good condition). We are currently deciding whether to re-insulate the sloping roof areas. We have spoken with an energy consultant, a drywall contractor specializing in insulation, as well as various tradespeople and friends.
To better assess the situation, here are the details:
The double-glazed wooden windows will remain, the masonry includes an air gap and 40mm (1.6 inches) of insulation, and two roof windows in the sloping roof will be replaced. The roof is currently insulated between the rafters with 140mm (5.5 inches) of glass wool (one side covered with aluminum foil). In front of the roof tiles, there is a kind of mesh membrane, and on the inside, drywall panels are attached to counter battens.
The existing insulation extends from the roof gable all the way down, and the attic floor ceiling is also insulated. The knee wall (dwarf wall) of the rooms is about 1.2m (47 inches) high and solidly built, with insulation behind it.
To receive funding, the effort would be too great. The plan is to increase the existing rafters to 200mm (7.9 inches) depth and insulate with glass wool having a thermal conductivity of 0.032 W/mK. The drywall contractor would remove the knee walls and rebuild them with drywall. He said it would be sufficient to do this only for the two children’s rooms and the bathroom. The bedroom and stairwell would remain as they currently are.
Does such partial insulation really make that much difference?
Is it at all sensible (considering thermal bridges, etc.) not to insulate all areas anew (bedroom, stairwell)?
If the roof needs to be replaced in about 15 years, would it then be better to insulate more effectively?
We are very torn because this was not originally planned, and we don’t know how much benefit the effort will bring. The costs for the three rooms will be just under 10,000 euros (plus electricity and labor, removal and disposal of the old insulation, etc.).
What should we do? We are really unsure...
we have purchased a house from the early 1980s (solid construction, the roof is still in very good condition). We are currently deciding whether to re-insulate the sloping roof areas. We have spoken with an energy consultant, a drywall contractor specializing in insulation, as well as various tradespeople and friends.
To better assess the situation, here are the details:
The double-glazed wooden windows will remain, the masonry includes an air gap and 40mm (1.6 inches) of insulation, and two roof windows in the sloping roof will be replaced. The roof is currently insulated between the rafters with 140mm (5.5 inches) of glass wool (one side covered with aluminum foil). In front of the roof tiles, there is a kind of mesh membrane, and on the inside, drywall panels are attached to counter battens.
The existing insulation extends from the roof gable all the way down, and the attic floor ceiling is also insulated. The knee wall (dwarf wall) of the rooms is about 1.2m (47 inches) high and solidly built, with insulation behind it.
To receive funding, the effort would be too great. The plan is to increase the existing rafters to 200mm (7.9 inches) depth and insulate with glass wool having a thermal conductivity of 0.032 W/mK. The drywall contractor would remove the knee walls and rebuild them with drywall. He said it would be sufficient to do this only for the two children’s rooms and the bathroom. The bedroom and stairwell would remain as they currently are.
Does such partial insulation really make that much difference?
Is it at all sensible (considering thermal bridges, etc.) not to insulate all areas anew (bedroom, stairwell)?
If the roof needs to be replaced in about 15 years, would it then be better to insulate more effectively?
We are very torn because this was not originally planned, and we don’t know how much benefit the effort will bring. The costs for the three rooms will be just under 10,000 euros (plus electricity and labor, removal and disposal of the old insulation, etc.).
What should we do? We are really unsure...
A
Alibert875 Apr 2023 16:09Does anyone else want to add their input? That would be great.
K
KarstenausNRW5 Apr 2023 20:30Honestly? Leave the roof with the already decent insulation as it is. Add another layer of mineral wool or similar insulation to the attic floor. The effort you want to invest now a) will never pay off (since only a small part of the building envelope is insulated) and you might save a few percent of energy (no idea exactly how much, it depends on the insulated area). 3%? 4%? But it definitely won’t be noticeably significant.
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