After just discovering a small mold attack in the attic, I'm pondering this issue with risky constructions.
Every amateur here on the forum knows you should never have organic material on the cold side of the insulation. We apply this knowledge daily in basement environments. For most people today, it's obvious to put the insulation on the outside. House manufacturers, of course, do the same.
However, when you lift your gaze a few meters, it's as if common sense drains from your head when it tips backward. Why do we stubbornly continue to build ice-cold attics with several tons of organic material on the WRONG side of the insulation?
There are solutions to insulate on the outside (or a combination of outside and inside), which completely eliminates this huge problem.
WHY do both house manufacturers and happy amateurs continue to build traditionally (but with more insulation = bigger problems)? It's outright idiotic.
Here's a link to an attempt at improvement:
http://www.thermisol.se/pdf/TH_tak broschyr_web2006.pdf
I believe, however, that ALL insulation should be on the outside; it shouldn't be a problem.
Every amateur here on the forum knows you should never have organic material on the cold side of the insulation. We apply this knowledge daily in basement environments. For most people today, it's obvious to put the insulation on the outside. House manufacturers, of course, do the same.
However, when you lift your gaze a few meters, it's as if common sense drains from your head when it tips backward. Why do we stubbornly continue to build ice-cold attics with several tons of organic material on the WRONG side of the insulation?
There are solutions to insulate on the outside (or a combination of outside and inside), which completely eliminates this huge problem.
WHY do both house manufacturers and happy amateurs continue to build traditionally (but with more insulation = bigger problems)? It's outright idiotic.
Here's a link to an attempt at improvement:
http://www.thermisol.se/pdf/TH_tak broschyr_web2006.pdf
I believe, however, that ALL insulation should be on the outside; it shouldn't be a problem.
Well, the idea is good, but there are a few disadvantages I can see based on the information with foam plastic boards on the roof:
* Requires an underlay of raw wood boards, which (unfortunately) takes time/cost to build today.
* Who wants to throw foam plastic boards on the roof when it's storming/snowing...
* Requires that the battens are screwed - it takes time! It also seems very slippery at steep slopes...
There are probably a couple more, and the construction industry is fairly conservative with "new" construction methods, sometimes rightfully so!
What had happened in the attic, by the way?
* Requires an underlay of raw wood boards, which (unfortunately) takes time/cost to build today.
* Who wants to throw foam plastic boards on the roof when it's storming/snowing...
* Requires that the battens are screwed - it takes time! It also seems very slippery at steep slopes...
There are probably a couple more, and the construction industry is fairly conservative with "new" construction methods, sometimes rightfully so!
What had happened in the attic, by the way?
That it takes a little longer is okay, I think. It is a small additional cost compared to decontaminating an attic from mold.
In my attic, a little white mold has formed in a very short time. The relative humidity is very high even though it is as sealed as possible downwards in an old house (plastic everywhere). The whole thing comes like clockwork after the additional insulation a couple of months ago.
While waiting for a permanent solution, I am now increasing the temperature up there with a car heater at night. It doesn't cost much and seems to yield results in temperature and relative humidity. However, the measurement results are a bit tricky since they are simple meters and I'm only measuring in the attic, not outside.
In my attic, a little white mold has formed in a very short time. The relative humidity is very high even though it is as sealed as possible downwards in an old house (plastic everywhere). The whole thing comes like clockwork after the additional insulation a couple of months ago.
While waiting for a permanent solution, I am now increasing the temperature up there with a car heater at night. It doesn't cost much and seems to yield results in temperature and relative humidity. However, the measurement results are a bit tricky since they are simple meters and I'm only measuring in the attic, not outside.
Hello!
I think you almost answer your own question!
You seem fully aware that an old, additionally insulated wooden attic is a risk construction. Yet, you've apparently just chosen to do it? Why didn't you tear it all down and rebuild with polystyrene on the outside while you were at it?
We are now also in the process of making an identical risk construction on our attic, i.e., additionally insulating it. Our house (40s-era detached home) I think would look somewhat amusing if we put a thick "hat" of polystyrene on top of the roof. I also suspect that roof tiles (which are a requirement from the city planning office for our area) can't be used then. So one reason that comes to mind right away is the aesthetics, either self-chosen or enforced for certain old houses.
Another reason to make risk constructions is that it's much simpler (which I suspect is your reason too, at least partly). Also, a risk construction doesn't necessarily mean that you will definitely have problems. It might go well too.
So another clear reason people choose risk constructions is that they are influenced by their already existing house.
However, when it comes to new constructions, I think there are far fewer excuses. But as I said, it didn't look so great after storm Per when the polystyrene roofs were blown every which way.... Tiles, battens, felt, and raw boards don't blow away as easily even though they are more prone to mold
/pinebar
I think you almost answer your own question!
You seem fully aware that an old, additionally insulated wooden attic is a risk construction. Yet, you've apparently just chosen to do it? Why didn't you tear it all down and rebuild with polystyrene on the outside while you were at it?
We are now also in the process of making an identical risk construction on our attic, i.e., additionally insulating it. Our house (40s-era detached home) I think would look somewhat amusing if we put a thick "hat" of polystyrene on top of the roof. I also suspect that roof tiles (which are a requirement from the city planning office for our area) can't be used then. So one reason that comes to mind right away is the aesthetics, either self-chosen or enforced for certain old houses.
Another reason to make risk constructions is that it's much simpler (which I suspect is your reason too, at least partly). Also, a risk construction doesn't necessarily mean that you will definitely have problems. It might go well too.
So another clear reason people choose risk constructions is that they are influenced by their already existing house.
However, when it comes to new constructions, I think there are far fewer excuses. But as I said, it didn't look so great after storm Per when the polystyrene roofs were blown every which way.... Tiles, battens, felt, and raw boards don't blow away as easily even though they are more prone to mold
/pinebar
One disadvantage of putting insulation on the roof can be that it becomes more expensive (larger area and more expensive insulation). No house manufacturer willingly chooses a more expensive method unless they can advertise it well and also get paid for it.
With all the insulation on the outside, doesn't the roof look strange?
But it's a bit surprising that there still aren't established and recognized methods for small house construction. If 20-30-40-50 years ago a number of test houses/test parts had been built with all conceivable methods, we would know today. This particular method you are referring to is a partisan plea. Sure, it can be good and sounds functionally better than the regular one. But it would still feel better if there were methods not endorsed by the material producers.
With all the insulation on the outside, doesn't the roof look strange?
But it's a bit surprising that there still aren't established and recognized methods for small house construction. If 20-30-40-50 years ago a number of test houses/test parts had been built with all conceivable methods, we would know today. This particular method you are referring to is a partisan plea. Sure, it can be good and sounds functionally better than the regular one. But it would still feel better if there were methods not endorsed by the material producers.
Why do you suspect that? According to Themisol's concept, you are supposed to batten up in the usual way on top of the foam insulation?pinebar said:
I don't understand why it would blow away either. The foam insulation is held in place by battens that are screwed through it, and on top of everything lies the roof tiles with all their weight. One might as well claim that a masonite sub-roof should blow away.
Had I had the same risk awareness five years ago as I do now, the construction might have been different. Of course, everything is more challenging when renovating, but I am mostly thinking about new production. Even there, they build in exactly the same way as they always have.pinebar said:Hey!
I feel like you're almost answering your own question!
You seem fully aware that an old additional insulated wooden attic is a risk construction. Yet you apparently recently chose to do it? Why didn't you tear it all down and rebuild with foam on the outside while you were at it?
We are now also in the process of making an exactly similar risk construction on our attic, i.e., adding insulation to it. Our house (40s private home) I think would look a bit odd if we put a thick "hat" of foam on the roof. I also suspect that roof tiles (which is a requirement from the city building office for our area) can't be used then. So one reason I can come up with directly is the aesthetics, either self-chosen or enforced for some old houses.
Another reason to make a risk construction is that it is much simpler (which I suspect is also your reason at least partly). Then a risk construction doesn't necessarily mean you will definitely have problems. It could go well too.
So another clear reason for choosing risk constructions is that you are guided by your already existing house.
However, for new construction, I think there are significantly fewer excuses. But as I said, it didn't look so great after storm Per when the foam roofs had blown away.... Tiles, battens, felt, and boards definitely don't blow away as easily even though they are more prone to mold
/pinebar
From a technical perspective, I'm sure there are no problems - you, of course, have to rebuild a little, but I see no obstacle for the houses to look the same as today even if they have insulation on the outside. It doesn't need to look different (hat) than today. Putting tiles on is not a problem either.
When house manufacturers really start experiencing guarantee repairs as a result of moldy houses, they will probably open their eyes to alternative building methods.Betong said:
I don't have a finished construction in my head, but I can't see any direct problems with applying all the insulation on the outside of the roof without it looking strange. It's just about mounting the roof deck a bit lower, if you will. At the eaves and overlaps on the gables, you don't need to have insulation, so it can look as usual there.
There are certainly other constructions than Thermisol's. It just happened to be the one I found first when I was searching. Spontaneously, I would like to see all the insulation on the outside, not just over half as Thermisol has done. Sure, it would be better if Boverket or SP showed how to build houses, but new constructions are likely to be driven forward by the manufacturers.
High as a house.Jonas_H said:
I only have cheap gadgets to measure with right now and they show a bit of anything, so I can't really say what the true value is. What I can conclude is that I have reduced the humidity by several percent at the same temperature, perhaps thanks to some nightly heating exercises. I have seen numbers between 85 and 94, but what is true, I don't know. TOO humid it is anyway.
Hello MathiasS
I read your thoughts and completely agree...surely it's logical that total external roof insulation brings many advantages...the dew point moves out and the internal attic volume can be used as valuable square meters.
I am also looking for optimal external roof insulation and have reviewed the market both domestically and in Europe where this method has been used for the past 20-25 years. Take a look at BASF's website for example or why not Maco Dach, which is now also available in Sweden?
Themisol is also on the same page but 16cm recessed polystyrene on the roof entails long expensive screws etc. Metal or tiles work as usual just as Fazman says.
Email me if you need more info/websites that should be checked etc.
Takman69
I read your thoughts and completely agree...surely it's logical that total external roof insulation brings many advantages...the dew point moves out and the internal attic volume can be used as valuable square meters.
I am also looking for optimal external roof insulation and have reviewed the market both domestically and in Europe where this method has been used for the past 20-25 years. Take a look at BASF's website for example or why not Maco Dach, which is now also available in Sweden?
Themisol is also on the same page but 16cm recessed polystyrene on the roof entails long expensive screws etc. Metal or tiles work as usual just as Fazman says.
Email me if you need more info/websites that should be checked etc.
Takman69
Post your links here if you have more! For me, it's already too late since the wind is already insulated, the roof has new paper, battens, and tiles.....
Here is the link to the Maco products:
http://www.maco-takisolering.com/tekinf.html
The additional insulation option must be interesting during renovation.
Here is the link to the Maco products:
http://www.maco-takisolering.com/tekinf.html
The additional insulation option must be interesting during renovation.
Interesting this...
Can I install insulation on my roof, which has a slope of about 6-7%, before I replace the underlay and install double-standing seam aluzinc?
I have kutterspån in the attic (no plastic anywhere...)
Need to look into this...
PJ
Can I install insulation on my roof, which has a slope of about 6-7%, before I replace the underlay and install double-standing seam aluzinc?
I have kutterspån in the attic (no plastic anywhere...)
Need to look into this...
PJ