ᐅ Roof insulation made of 100mm thick rigid polyurethane (PU) foam
Created on: 21 Oct 2019 09:19
A
Ankeffm
Hello everyone,
I urgently need some advice and tips regarding roof insulation.
We plan to have our roof replaced next year. Now, the topic is roof insulation. Our roofer recommended the following:
Polyurethane (PU) rigid foam, 100mm (4 inches) thick // Type: puren Protect N 023.
This would be an insulation installed above the rafters (i.e., external insulation). However, I have read in forums and other sources that sound insulation with this type of material often falls short. The noise level can sometimes be quite high. This is partly due to the boards themselves (as they apparently expand and contract, especially at night) and also because the boards do not provide good soundproofing.
We would really like the space under the roof to be more comfortable in summer and, of course, quieter—or at least that outside noise levels are bearable.
Can you give us advice on the best way to insulate a roof like this? Has anyone had experience with this type: puren Protect N 023?
Please help... THANK YOU!!!
Best regards, Anke
I urgently need some advice and tips regarding roof insulation.
We plan to have our roof replaced next year. Now, the topic is roof insulation. Our roofer recommended the following:
Polyurethane (PU) rigid foam, 100mm (4 inches) thick // Type: puren Protect N 023.
This would be an insulation installed above the rafters (i.e., external insulation). However, I have read in forums and other sources that sound insulation with this type of material often falls short. The noise level can sometimes be quite high. This is partly due to the boards themselves (as they apparently expand and contract, especially at night) and also because the boards do not provide good soundproofing.
We would really like the space under the roof to be more comfortable in summer and, of course, quieter—or at least that outside noise levels are bearable.
Can you give us advice on the best way to insulate a roof like this? Has anyone had experience with this type: puren Protect N 023?
Please help... THANK YOU!!!
Best regards, Anke
B
boxandroof22 Oct 2019 10:44@Ankeffm Find someone who takes this topic as seriously as you do. Possibly work with an architect and then give the contractors very specific instructions. This also makes it easier to compare bids. A friend is currently renovating his old building, and they are installing 14 or 16cm (5.5 or 6.3 inches) of mineral wool between the rafters. Additionally, there is continuous insulation with wood fiber as heat protection. That was the architect’s suggestion; the contractors had other ideas.
10cm (4 inches) of lightweight, expensive material is simply not enough. It’s better to invest the money in thicker insulation and mass. If you’re replacing the roof, do it properly. Have you read about the U-value calculator and phase shift?
Heat protection depends on the specific conditions and what is necessary. We manage very well with "only" 20cm (8 inches) of mineral wool as cavity insulation between the rafters, and thanks to a third gable facing south, we have only a small unprotected roof area behind the living spaces (maximum 26°C, 79°F). The attic is insulated (up to about 30°C, 86°F) but unoccupied. Sound insulation is not great, but that doesn’t matter for us.
10cm (4 inches) of lightweight, expensive material is simply not enough. It’s better to invest the money in thicker insulation and mass. If you’re replacing the roof, do it properly. Have you read about the U-value calculator and phase shift?
Heat protection depends on the specific conditions and what is necessary. We manage very well with "only" 20cm (8 inches) of mineral wool as cavity insulation between the rafters, and thanks to a third gable facing south, we have only a small unprotected roof area behind the living spaces (maximum 26°C, 79°F). The attic is insulated (up to about 30°C, 86°F) but unoccupied. Sound insulation is not great, but that doesn’t matter for us.
Hello @boxandroof,
Thank you very much for your post!
Yes, you are right... I will contact an architect. You invest (a very, very, very) large amount of money in the roof, so it should definitely be done well and be satisfactory afterwards.
Using wood fiber insulation as a continuous insulation layer above the rafters and mineral wool between the rafters is also my plan. As I mentioned before, and as you pointed out as well, the builders absolutely don’t offer this option.
Yes, I have read about the thermal phase shift... but sorry, I don’t understand the calculator. I’ll have to review it more carefully later.
It’s great to hear you are happy with your roof! Thanks to everyone who actively shares their thoughts here... Even though the topic was a bit boring in the beginning, I find it increasingly interesting.
Thanks to everyone! Please feel free to share more experiences.
Thank you very much for your post!
Yes, you are right... I will contact an architect. You invest (a very, very, very) large amount of money in the roof, so it should definitely be done well and be satisfactory afterwards.
Using wood fiber insulation as a continuous insulation layer above the rafters and mineral wool between the rafters is also my plan. As I mentioned before, and as you pointed out as well, the builders absolutely don’t offer this option.
Yes, I have read about the thermal phase shift... but sorry, I don’t understand the calculator. I’ll have to review it more carefully later.
It’s great to hear you are happy with your roof! Thanks to everyone who actively shares their thoughts here... Even though the topic was a bit boring in the beginning, I find it increasingly interesting.
Thanks to everyone! Please feel free to share more experiences.
B
boxandroof22 Oct 2019 11:42Ankeffm schrieb:
Yes, I have read about the phase shift... but I'm sorry, I don’t understand the calculator. With 10cm (4 inches) of light insulation such as mineral wool or your 0.23 W/(m²·K) rigid foam board, heat will theoretically pass through to the interior after 3-4 hours. With 20cm (8 inches), it takes 5-6 hours. Ideally, you want 10-12 hours because then the heat is released to the outside overnight rather than inside. This cannot be achieved with only light insulation materials; you need heavier materials with somewhat lower insulation values.
The calculator lets you determine this value among others so you can roughly evaluate proposals for roof constructions yourself. Now you know the result for 10cm (4 inches).
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garfunkel22 Oct 2019 17:03Yes, I have the PUR insulation, and yes, there are only 5 cm (2 inches) of mineral wool. The total insulation thickness is, I believe, 20 cm (8 inches), if I’m not mistaken.
As I wrote, I am (very) satisfied with the heat protection. I don’t have any insulation between the rafters because I have an exposed rafter roof structure.
Based on my research, I can only say that PUR is not the right choice if you want effective sound insulation. There are better options for that.
However, when considering the entire construction, you shouldn’t forget that sound can also enter the living space through other ways, especially in older buildings where not everything is perfect or can be made perfect.
To summarize what has been discussed in this thread: PUR is good and cost-effective, but there are better choices, especially for sound and heat insulation.
As I wrote, I am (very) satisfied with the heat protection. I don’t have any insulation between the rafters because I have an exposed rafter roof structure.
Based on my research, I can only say that PUR is not the right choice if you want effective sound insulation. There are better options for that.
However, when considering the entire construction, you shouldn’t forget that sound can also enter the living space through other ways, especially in older buildings where not everything is perfect or can be made perfect.
To summarize what has been discussed in this thread: PUR is good and cost-effective, but there are better choices, especially for sound and heat insulation.
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