New 860 sq. ft. passive house
Last Post 28 Aug 2014 10:12 PM by Torben. 9 Replies.
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lamazoidasUser is Offline
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26 Aug 2014 06:09 AM
Hi, I am planning to build 1 floor 860 sq. ft. house with SIP on planar foundation with simple flat - mono pitch roof. My "sandwich" will look like this: SIP 124mm = 12mm OSB3 + 100mm eps + 12mm OSB3 + 200mm NEPS from outside + inside (vapor barrier + gypsum + gypsum). And this is what I get with such sandwich: http://www.u-wert.net/berechnung/u-wert-rechner/?&d0=1&mid0=195&d1=1&mid... Foundation will be insulated with 150mm EPS. Floor will be insulated with 300mm EPS. Roof (SIP 124mm + 45mm rockwool from inside) The inner walls of the house will be from silicate bricks. Ofcource there will be HRV. House heating will be electric (202 eur/270USD per year). I chose SIP, since my house will be small, it will be easy to build on my own and price is very acceptable. My climate is Humid continental. Any suggestons?
JellyUser is Offline
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26 Aug 2014 08:26 AM
100mm EPS klingt relativ dünn. How cold is the Winter where you live?
lamazoidasUser is Offline
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27 Aug 2014 01:17 AM
In Europe we have houses from SIP, which has such wall: 7.9 NEPS + 4.9 inches SIP sandwich + aluminum foil, wich is glued to OSB from house interior + 2 inches of wool + gypsum + gypsum.
NEPS - graphite-enhanced polystyrene (neopor).
So on neps we put decor + neps reduces the opportunity to appear for cold bridges from outside.
Aluminum foil acts as an extra vapor protection and as protection from toxic substances such as glue wich connects OSB and polystyrene.
Wool acts as a sound protection + you can hide wires there.
So wall will be proximately about 324mm. (SIP 124mm + 200mm graphite-enhanced polystyrene).
In my country winter's average temperature is -10 up to -30 C.
jonrUser is Offline
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27 Aug 2014 11:11 AM
So the roof is about 1/2 the R value of everything else? I'd carefully adjust the HRV balance as the primary method of avoiding toxic substances coming in from the walls. This is more effective than trying to block it with aluminum foil or diluting it once it is inside.

Not sure why the US doesn't use much graphite in foam.
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27 Aug 2014 01:22 PM
Posted By jonr on 27 Aug 2014 11:11 AM
So the roof is about 1/2 the R value of everything else? I'd carefully adjust the HRV balance as the primary method of avoiding toxic substances coming in from the walls. This is more effective than trying to block it with aluminum foil or diluting it once it is inside.

Not sure why the US doesn't use much graphite in foam.

In a word, patents.  

BASF's Neopor is the only graphite-enhanced foam insulation out there, and though it's available, it is not in wide distribution in the US.  The nearest distributor to me is 105 miles away, and it has to be special-ordered. SFAIK few (or no?) US distributors actually keep it in stock, which creates a scheduling hurdle to overcome.
jonrUser is Offline
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27 Aug 2014 01:57 PM
I would have guessed that many other materials would offer similar radiant blocking abilities.
lamazoidasUser is Offline
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28 Aug 2014 03:17 AM
For me the biggest problem is how to avoid vapor getting in to the walls and roof since in my country there is very humid climate. Lets say i have such wall from ourside: Decor, stucco, neopor 350mm, SIP sandwich 130mm, gypsum, gypsum. I know (or it is said) that OSB is impervious to vapor, but still i will put aluminum foil from interior on to the OSB. But what about from outside OSB, just before neopor, should i put any vapor barrier or instead i should put wind barrier? Since neopor is permeable to wind.

jonrUser is Offline
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28 Aug 2014 11:30 AM
I'm not aware of any wall that will perform better with multiple vapor barriers (like aluminum foil). Vapor getting out can be as important as it not getting in. Some even claim that walls shouldn't have any Class I vapor retarders.

What is decor?
JellyUser is Offline
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28 Aug 2014 07:04 PM
I understood decor to be the cosmetic finish.
TorbenUser is Offline
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28 Aug 2014 10:12 PM
In a humid climate your wall assembly needs to have the vapor barrier on the outside and the wall assembly needs to be able to dry toward the inside. If you block the inside with a vapor barrier you will likely have problems.
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