Hello,
I have a roof without full sheathing, so rafters with cross battens directly supporting the roof tiles. Since last winter, strong winds caused up to 10cm (4 inches) of snow to quickly get under the roof, I now want to seal/insulate my roof. Since I am doing this, I also plan to convert the gained space into a living area in the future.
One of the few options, without having to completely re-roof, is, according to my information, insulation using sprayed foam.
I have received two different offers for this.
Offer 1 – VonWaldIso
Install a fleece layer between the rafters, then spray rigid polyurethane foam with a density of 32kg/m³ (2 pounds per cubic foot) between the rafters.
Offer 2 – Stocker
Install a membrane (foil) between the rafters, then spray Icynene foam (Smartisol) between the rafters – with a layer about twice as thick as the PU offer.
Because of the double thickness of the Icynene insulation, the insulation effect would be about the same as with the polyurethane foam.
Both companies also recommend insulating the gable walls with foam.
The gable walls, like the rest of the house, are made of 28cm (11 inches) Durisol masonry (formwork blocks made from mineralized wood chips), with a ventilated fiber cement facade (Eternit) on the outside.
The costs for both options are roughly the same.
Now I am wondering which system is better suited for my needs.
PU foam is closed-cell, so it is completely waterproof, vapor-tight, and airtight. A vapor barrier or vapor retarder could therefore be omitted in further finishing.
Icynene foam is vapor-open but, according to the manufacturer, waterproof. In further finishing, would I then need to proceed as with fiberglass insulation and install a vapor barrier/retarder? Or can I also build directly on top with battens and drywall?
My gut feeling leans toward the PU insulation, although I can’t really justify it. When reading into it, I somehow felt it might be the better option.
Since facts and real experience are surely better guides than my gut feeling, I would appreciate your opinions.
Best regards,
Mike
I have a roof without full sheathing, so rafters with cross battens directly supporting the roof tiles. Since last winter, strong winds caused up to 10cm (4 inches) of snow to quickly get under the roof, I now want to seal/insulate my roof. Since I am doing this, I also plan to convert the gained space into a living area in the future.
One of the few options, without having to completely re-roof, is, according to my information, insulation using sprayed foam.
I have received two different offers for this.
Offer 1 – VonWaldIso
Install a fleece layer between the rafters, then spray rigid polyurethane foam with a density of 32kg/m³ (2 pounds per cubic foot) between the rafters.
Offer 2 – Stocker
Install a membrane (foil) between the rafters, then spray Icynene foam (Smartisol) between the rafters – with a layer about twice as thick as the PU offer.
Because of the double thickness of the Icynene insulation, the insulation effect would be about the same as with the polyurethane foam.
Both companies also recommend insulating the gable walls with foam.
The gable walls, like the rest of the house, are made of 28cm (11 inches) Durisol masonry (formwork blocks made from mineralized wood chips), with a ventilated fiber cement facade (Eternit) on the outside.
The costs for both options are roughly the same.
Now I am wondering which system is better suited for my needs.
PU foam is closed-cell, so it is completely waterproof, vapor-tight, and airtight. A vapor barrier or vapor retarder could therefore be omitted in further finishing.
Icynene foam is vapor-open but, according to the manufacturer, waterproof. In further finishing, would I then need to proceed as with fiberglass insulation and install a vapor barrier/retarder? Or can I also build directly on top with battens and drywall?
My gut feeling leans toward the PU insulation, although I can’t really justify it. When reading into it, I somehow felt it might be the better option.
Since facts and real experience are surely better guides than my gut feeling, I would appreciate your opinions.
Best regards,
Mike
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