Hello.
We will be building a single-family house in 2016. Our budget is tight. Including a contingency, we have 300,000 euros available for 160 sqm (1,722 sq ft) (excluding landscaping, no basement, no carport). Our architects are currently preparing the tenders for the individual trades. As indicated in the subject, we need to decide soon on the insulation for the roof. For the thermal protection certificate according to the Energy Saving Ordinance 2014, 24 cm (9.5 inches) of mineral wool 035 was calculated for the roof. However, our architects recommend using blown-in loose-fill insulation instead. This is said to provide better protection against summer heat in particular. Since some of our rooms will have very high ceilings and extend right up to the roof, this argument could indeed be important. We are, however, concerned about the higher costs of loose-fill insulation and also worry that blown-in insulation might settle downward (pitched roof) causing a gap to form at the ridge.
What do you think? Are there any experiences regarding the costs and potential compression or settling of loose-fill insulation?
Thanks and best regards.
We will be building a single-family house in 2016. Our budget is tight. Including a contingency, we have 300,000 euros available for 160 sqm (1,722 sq ft) (excluding landscaping, no basement, no carport). Our architects are currently preparing the tenders for the individual trades. As indicated in the subject, we need to decide soon on the insulation for the roof. For the thermal protection certificate according to the Energy Saving Ordinance 2014, 24 cm (9.5 inches) of mineral wool 035 was calculated for the roof. However, our architects recommend using blown-in loose-fill insulation instead. This is said to provide better protection against summer heat in particular. Since some of our rooms will have very high ceilings and extend right up to the roof, this argument could indeed be important. We are, however, concerned about the higher costs of loose-fill insulation and also worry that blown-in insulation might settle downward (pitched roof) causing a gap to form at the ridge.
What do you think? Are there any experiences regarding the costs and potential compression or settling of loose-fill insulation?
Thanks and best regards.
K
Komposthaufen3 May 2016 16:56We are building with architects and managing individual contracts ourselves. So far, it’s going very well. Even the "absent-minded professor" is manageable 🙂
It was actually a typo. The rafters will be 24 cm (9.5 inches) thick. So, the insulation between the rafters will also be 24 cm (9.5 inches). Regarding the roof structure, all three types of insulation mentioned above should be possible in our case.
In my online research, unfortunately, I couldn’t find a clear overview of the advantages and disadvantages of the different insulation types and products. If anyone has a link for me, please send it via private message.
What I have found out so far:
Is this correct so far?
Thanks very much for your advice.
It was actually a typo. The rafters will be 24 cm (9.5 inches) thick. So, the insulation between the rafters will also be 24 cm (9.5 inches). Regarding the roof structure, all three types of insulation mentioned above should be possible in our case.
In my online research, unfortunately, I couldn’t find a clear overview of the advantages and disadvantages of the different insulation types and products. If anyone has a link for me, please send it via private message.
What I have found out so far:
- The best price-performance ratio in terms of thermal protection is offered by mineral wool.
- Slightly lower thermal protection but significantly better summer heat protection is provided by cellulose fiber insulation, which is only slightly more expensive. However, I haven’t found any information on dimensional stability and the risk of compression over the years. That would be my biggest concern for a pitched roof.
- The highest quality seems to be wood fiber boards, which offer acceptable thermal protection along with good summer heat resistance and good sound insulation values. Among the three insulation options, the boards are also the most expensive.
Is this correct so far?
Thanks very much for your advice.
We had wood fiber insulation blown in. According to our carpenter, there are regulations regarding the required pressure/density for filling the cavities. If applied properly, this should prevent any settling afterwards. When we observed the blowing process in practice, we got the impression that this is indeed the case. Of course, we are only laypersons...
This is said to be more difficult with mineral wool, as perfect installation is more challenging and labor-intensive.
This is said to be more difficult with mineral wool, as perfect installation is more challenging and labor-intensive.
Expensive does not always mean high quality... 😀
The situation changes completely when cables and lines (preferably controlled residential ventilation at this stage) run through the cavities. Then even the "best" materials can become quite problematic. Mineral wool is no better in this regard.
Regarding the myth of settling: I can show you pictures of wall openings where cavities insulated with mineral wool have also settled. 😡
As for blowing insulation: the material is blown in under pressure to ensure even compaction. However, this requires proper planning so that the structural conditions are met and the cavities are not too large. For example, I cannot fully fill a 7m (23 ft) long slope in one go. It depends on the planning and the installer. If the drywall installer just works carelessly by hand, you can forget about good results.
Conclusion: Mineral wool does have better thermal conductivity (better R-value), that is true. But to be fair, you have to compare 40 to 40. In that case, mineral wool can never be cheaper than cellulose.
The situation changes completely when cables and lines (preferably controlled residential ventilation at this stage) run through the cavities. Then even the "best" materials can become quite problematic. Mineral wool is no better in this regard.
Regarding the myth of settling: I can show you pictures of wall openings where cavities insulated with mineral wool have also settled. 😡
As for blowing insulation: the material is blown in under pressure to ensure even compaction. However, this requires proper planning so that the structural conditions are met and the cavities are not too large. For example, I cannot fully fill a 7m (23 ft) long slope in one go. It depends on the planning and the installer. If the drywall installer just works carelessly by hand, you can forget about good results.
Conclusion: Mineral wool does have better thermal conductivity (better R-value), that is true. But to be fair, you have to compare 40 to 40. In that case, mineral wool can never be cheaper than cellulose.
S
Sebastian793 May 2016 20:04We did both – mineral wool insulation between the rafters with a thickness of 200mm to 240mm (8 to 9.5 inches), and then an additional 60mm (2.5 inches) of wood fiber boards on top.
N
nightdancer5 May 2016 10:15Wood fiber in this context is beneficial both for ecological reasons and for the builders' budget. I would choose cellulose insulation, but whether the thermal protection is noticeably different at such a low thickness (other than in your perception) is something no one can really prove.
You can try searching for a video from Isover on YouTube, where this topic is discussed.
You can try searching for a video from Isover on YouTube, where this topic is discussed.
S
Sebastian795 May 2016 10:20And Isover wants an explanation for that 😀?
The panels have a calculated summer heat protection and also eliminate the need for a vulnerable vapor barrier, providing a weatherproof temporary roof and effective vapor diffusion. Yes, it’s more expensive, but it combines many advantages – we were also able to avoid installing intermediate batt insulation since we only have 20cm (8 inches) rafters.
The panels have a calculated summer heat protection and also eliminate the need for a vulnerable vapor barrier, providing a weatherproof temporary roof and effective vapor diffusion. Yes, it’s more expensive, but it combines many advantages – we were also able to avoid installing intermediate batt insulation since we only have 20cm (8 inches) rafters.
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