Home>Discussions>INSULATION & HVAC>Hot roof vs. cold roof: problems with city inspectors
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Re: Hot roof vs. cold roof: problems with city inspectors

It wouldn't surprise me if the municipality has made that a requirement not for tax assessment but to avoid improper insulation installation which could lead to mold, etc. However, from what you've described I don't feel that would be a problem since you are making it interior space, effectively.

What I really, really, don't get is why they would want you to furr out the rafters, since burying them in insulation prevents thermal bridging. Is it possible that this attic space could be finished into storage/usable space? Are they worried someone would put up drywall directly over the insulation in future? I don't see snow load as a problem since they are existing and it was a cold attic as it was. How big of a volume is the space? I assume it has an access panel, typically attic space less than 24" in clear height does not require access (new construction, of course).

I wouldn't, personally, bother with a variance since it could affect selling your house in the future, if your municipality requires inspections, etc.

Re: Hot roof vs. cold roof: problems with city inspectors
jkirk wrote:

otherwise consult an engineer to get a A-9 letter which the building official then has to obey. inspectors cant over rule an engineer

Only the city engineer..... :)

Netdewt
Re: Hot roof vs. cold roof: problems with city inspectors
ChicagoCooperator wrote:

It wouldn't surprise me if the municipality has made that a requirement not for tax assessment but to avoid improper insulation installation which could lead to mold, etc. However, from what you've described I don't feel that would be a problem since you are making it interior space, effectively.

What I really, really, don't get is why they would want you to furr out the rafters, since burying them in insulation prevents thermal bridging. Is it possible that this attic space could be finished into storage/usable space? Are they worried someone would put up drywall directly over the insulation in future? I don't see snow load as a problem since they are existing and it was a cold attic as it was. How big of a volume is the space? I assume it has an access panel, typically attic space less than 24" in clear height does not require access (new construction, of course).

I wouldn't, personally, bother with a variance since it could affect selling your house in the future, if your municipality requires inspections, etc.

Our city is very strict about home inspections. A home must be inspected prior to sale, and they make people change things often.

The "attic" is currently 75% livable space, and we want to finish it further to 95% livable space. It's about 400-500 sq ft or with 82" ceiling. The total house footprint is about 800 sq ft, so the remainder is below walkable ceiling height.

Because of fire codes, we have to sheetrock anything accessible.

Right now I am feeling like we have to comply with the city and install 1.5" vent chutes, a ridge vent, and fir out the 2x4"s by 2" to get enough insulation in the roof deck. Also, the city does not allow the plastic curved vent chutes because they don't go all the way to the edge.

Current plan:

Netdewt
Re: Hot roof vs. cold roof: problems with city inspectors
jkirk wrote:

fine home building magazine did a article on just this topic a few issues ago. with detailed sketches and engineering reports.. check their website for it and present it to your building official.

Do you happen to know which issue? I'm not finding anything on their website.

keith3267
Re: Hot roof vs. cold roof: problems with city inspectors

If you have 2x4 rafters, you are going to need a lot more than a 2x2 furring strip. Most places require a minimum of R-19. With a 2x2 furring strip, your total depth will be only 5" and with a required 1.5" chute for ventilation, that only leaves room for R-11. You could use R-11 and then attach 2" thick rigid foam panels to the furring strips and then the sheetrock. That would give you the required R-19, and it would block heat loss through the furring strips and rafters.

If you have 2x4 rafters, what do you have for ceiling joists? Based on your dimensions, it looks like you would need at least 2x8's, maybe 2x10's

Netdewt
Re: Hot roof vs. cold roof: problems with city inspectors

It's all 2x4". 1955 construction. The "ridge beam" and truss chords are 1x4". Are you saying my house is going to fall down?

R19 in walls and slants, R38 in flats is what the inspector told me, but he also said 2x2" is enough.

keith3267
Re: Hot roof vs. cold roof: problems with city inspectors

The house won't fall down, but the floor will feel like a trampoline. You will crack and lose the plaster in all your ceilings below. You need to consult with a structural engineer or architect before you do this. I think your city needs to hire a new inspector if he thinks you can stuff R-19 into 3.5" of space and that a 2x4 is OK for a floor joist.

To make this into living space, you really should have 2x8 rafters and 2x10 joists. You might get by with 2x6 rafters and 2x8 joists, I think this is what they allowed for a living space in the roof back in 1955. In the sub division of the first house I bought, back in 77, they used 2x6 rafters and 2x8 joists in the houses with a second story in the roof where the regular 1 story houses got 2x4 trusses. I think they have bumped up the second story requirements by an additional 2" since.

Netdewt
Re: Hot roof vs. cold roof: problems with city inspectors

OH! The floor of the "attic" is 2x10 at least I think. Same as the main floor. The "attic" is already finished. We are just updating it to sheetrock, adding a bathroom, and want to improve the insulation at the same time.

keith3267
Re: Hot roof vs. cold roof: problems with city inspectors

2x10, that's better. I'm surprised that the rafters are only 2x4 though, I would expect at least 2x6. Maybe that is what the inspector thinks is there and that is why he said a 2x2 furring strip was all that is needed. Normally you would have insulation in the floor of those storage spaces, the knee walls, the slants and the ceiling over the living spaces.

Netdewt
Re: Hot roof vs. cold roof: problems with city inspectors

Yes that's what we have, except the storage space also has fiberglass hanging loosely on the slants.

I'll have to clarify the thickness they want, but based on a quick search it looks like 3" of spray foam would be R-18.

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