ᐅ Thin interior insulation in addition to exterior insulation (risk of condensation?)
Created on: 21 Apr 2017 13:01
W
world-eHello everyone,
for my basement (24cm (9.5 inches) thick waterproof concrete plus 12cm (5 inches) perimeter insulation), I would like to cover the exterior walls in one room with Fermacell composite panels (1cm (0.4 inches) Fermacell on 3cm (1.2 inches) polystyrene) to also accommodate some electrical installations. The interior walls are masonry and will be plastered as usual. Ideally, the concrete walls should not be plastered; instead of plaster, the Fermacell panels will be installed. Most of the electrical installation is inside the interior walls. This concerns only one room, which has a light well and is intended as a hobby or guest room. Therefore, this room should look nicer than the other basement rooms. The site manager did not want to install electrical boxes in the waterproof concrete, probably to avoid nails in the formwork and due to concerns about waterproofing.
My questions are:
Can condensation occur with this setup without a vapor barrier? According to the U-value calculator, the assembly should work, especially since there is 12cm (5 inches) of insulation on the outside. Do you have any other suggestions? I would rather avoid surface-mounted electrical installation. The composite panels seem simpler to me than first building a substructure and then installing gypsum fiberboards. Otherwise, the two exterior walls would also need to be plastered or at least sanded and filled.
Thank you very much.
for my basement (24cm (9.5 inches) thick waterproof concrete plus 12cm (5 inches) perimeter insulation), I would like to cover the exterior walls in one room with Fermacell composite panels (1cm (0.4 inches) Fermacell on 3cm (1.2 inches) polystyrene) to also accommodate some electrical installations. The interior walls are masonry and will be plastered as usual. Ideally, the concrete walls should not be plastered; instead of plaster, the Fermacell panels will be installed. Most of the electrical installation is inside the interior walls. This concerns only one room, which has a light well and is intended as a hobby or guest room. Therefore, this room should look nicer than the other basement rooms. The site manager did not want to install electrical boxes in the waterproof concrete, probably to avoid nails in the formwork and due to concerns about waterproofing.
My questions are:
Can condensation occur with this setup without a vapor barrier? According to the U-value calculator, the assembly should work, especially since there is 12cm (5 inches) of insulation on the outside. Do you have any other suggestions? I would rather avoid surface-mounted electrical installation. The composite panels seem simpler to me than first building a substructure and then installing gypsum fiberboards. Otherwise, the two exterior walls would also need to be plastered or at least sanded and filled.
Thank you very much.
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