sgo70
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New Member
Posts:74
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| 08/18/2009 9:06 AM |
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| I'm moving along on my house, got the foundation pretty much done, the main floor is framed up and I'm gonna start sheeting it today, the SIPs start arriving on thursday and I'm still working on my temporary permit. I'm not allowed to go up past the main subfloor until I get it and I just got a phone call with another delay. The inspector won't let me use 2lb spray foam in the cathedral ceiling without vents so now I have to give him some venting detail drawings. I was hoping I could find something on the internet rather than having to pay my architect more money not to mention the time factor.
I also asked about adding cellulose batts below it and he said then I need a vapour barrier on the warm side. When I questioned him about the double barrier he said that's what you have to do, it's code. Am I wrong thinking this is a vapour trap? I tried contacting the spray foam company to see if they can help but no call back yet, last time I talked to him he said we can get it approved but I'm not sure about that.
Sean |
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Polycore
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New Member
Posts:64
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| 08/20/2009 10:41 AM |
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| Vapor Trap. Some inspectors are great and some are not. The only way to convince him that you are right is to find something that clearly states that you should only have one layer of vapor barrier. If you can find it in the code, you will prove your point, his job is to inforce the local building code so he can't argue with that. |
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Polycore Canada Inc.
www.polycorecanada.com
1-877-765-9267 |
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smartwall
Registered Users
Basic Member
Posts:129
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| 08/20/2009 12:55 PM |
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| Delta makes a high perm rated roof underlayment that I have used to aleviate any questions with my local inspectors where spray foam is used. |
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Jelly
Registered Users
Basic Member
Posts:496
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| 08/20/2009 7:57 PM |
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| Sean, does your area use the IRC? I've been lucky so far - my building inspector seems pretty laissez-faire. But then I just started... |
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sgo70
Registered Users
New Member
Posts:74
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| 08/25/2009 6:56 PM |
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| Well still trying to get by this guy and getting even more frustrated.
I talked to the spray foam company and they said they can vent it with the styrofoam baffles, cheap and easy right? He still won't go for it even though that's what they normally do, he said an engineer will have to sign it off because the foam will touch the exterior sheeting along the sides . So I sent him some drawings showing how I could fur out the entire roof leaving an air gap from the soffit to a ridge vent giving me 1.5" of vent space but that's a lot of extra work and money.
So then I get a call from the spray foam guy again and he tells me he has the name of a building envelope engineer that will sign it all off and give me two inspections (before drywall and completion) for around $1500. Thing is he prefers it to be all unvented .
Not sure which way to go now, guess I'll call the inspector tomorrow and see.
Sean |
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dmaceld
Registered Users
Advanced Member
Posts:805
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| 08/26/2009 1:20 AM |
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sgo, are you under the IRC? If so, here's the requirement from the 2006 IRC.
R806.3Vent and insulation clearance. Where eave or cornice
vents are installed, insulation shall not block the free flow of
air. A minimum of a 1-inch (25 mm) space shall be provided
between the insulation and the roof sheathing and at the location
of the vent.
R806.4 Conditioned attic assemblies. Unvented conditioned
attic assemblies (spaces between the ceiling joists of the top
story and the roof rafters) are permitted under the following
conditions:
1. No interior vapor retarders are installed on the ceiling
side (attic floor) of the unvented attic assembly.
2. An air-impermeable insulation is applied in direct contact
to the underside/interior of the structural roof deck.
“Air-impermeable” shall be defined by ASTM E 283.
Exception: In Zones 2B and 3B, insulation is not
required to be air impermeable.
3. In the warm humid locations as defined in Section
N1101.2.1:
3.1. For asphalt roofing shingles: A 1-perm (5.7 ×
10-11 kg/s ⋅ m2 ⋅ Pa) or less vapor retarder (determined
using Procedure B of ASTM E 96) is
placed to the exterior of the structural roof deck;
that is, just above the roof structural sheathing.
3.2. For wood shingles and shakes: a minimum continuous
1/4-inch (6 mm) vented air space separates
the shingles/shakes and the roofing felt
placed over the structural sheathing.
4. In Zones 3 through 8 as defined in Section N1101.2, sufficient
insulation is installed to maintain the monthly
average temperature of the condensing surface above
45°F (7°C). The condensing surface is defined as either
the structural roof deck or the interior surface of an
air-impermeable insulation applied in direct contact with
the underside/interior of the structural roof deck.
“Air-impermeable” is quantitatively defined by ASTM
E 283. For calculation purposes, an interior temperature
of 68°F (20°C) is assumed. The exterior temperature is
assumed to be the monthly average outside temperature.
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Building house - what a way to spend retirement! It's done! We're living in it! |
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sgo70
Registered Users
New Member
Posts:74
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| 08/26/2009 8:59 AM |
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| Thanks for that, I'm in Calgary, Canada so I have to follow the National Building Code as well as the Alberta Building Code. I'm going to look into these a little more and see if I can find something similar.
I'm not sure what the IRC is??
Sean |
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dmaceld
Registered Users
Advanced Member
Posts:805
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| 08/26/2009 10:04 AM |
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International Residential Code. I'm not familiar w/ the Canadian codes but I wouldn't be surprised if they aren't very similiar to, or based on, the IRC.
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Building house - what a way to spend retirement! It's done! We're living in it! |
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sgo70
Registered Users
New Member
Posts:74
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| 08/27/2009 10:24 AM |
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| Good news for me, he went for the last idea of furring it out and using the ridge vent. He actually issued my permit about an hour after I sent the revised drawings.
There is something I found funny though, he wants a vapour barrier between the drywall and trusses, unless I fill the whole cavity with the foam. All this is just leading me to use the 1/2lb foam since I need venting and vapour barrier I might as well save $4000 while I'm at it.
Thanks for all your input,
Sean |
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joe.ami
Registered Users
Veteran Member
Posts:1418
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| 08/27/2009 11:04 AM |
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| Inspectors are limited to the rules in the code they enforce. If you propose something that is not in their book, their only fall back is "specific engineering" which can be expensive. I would suggest in a case like yours that it be suggested to the insulation contractor that they are responsible for working it out with inspector. If you are doing the insulation then you found out what part of the contractor mark up is for. |
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Just a Mechanic;
Geothermal; Savings Underfoot |
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