Vapor Barrier For Finishing Old Attic

 
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Old 08-25-2012, 12:24 PM   #1
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Vapor Barrier For Finishing Old Attic


It's an old uninsulated house and there are no exterior vents in the attic. There will be only four sheetrock openings: two outlets, one switch plate, and one ceiling fixture. I can seal them with foam gaskets? (I should, right?)

Do I just use craft faced insulation on the outside walls and roof under deck as a vapor barrier (paper side in)? Or because the roof isn't vented, do I need to do more?

Do I REALLY need to cut the ridge off the roof and add a ridge vent? I'm really hoping to avoid calling in a roofer if possible.

(I searched around but all the attic questions seem to be about floor batts and not about outside walls / roof under decks).

Any guidance is appreciated.

Last edited by nycphotography; 08-26-2012 at 01:39 AM.
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Old 08-28-2012, 09:41 AM   #2
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Re: Vapor Barrier For Finishing Old Attic


Are you saying that you have a living space under your deck? Like a ceiling?

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Old 08-28-2012, 03:38 PM   #3
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Re: Vapor Barrier For Finishing Old Attic


I would vent it. Install baffles and then insulate.
You are going to want to make sure you have venting at the soffit and the ridge.
Or you could have some closed cell insul sprayed in.
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Old 08-28-2012, 04:06 PM   #4
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Re: Vapor Barrier For Finishing Old Attic


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Originally Posted by Chill-Out View Post
Are you saying that you have a living space under your deck? Like a ceiling?
I'm saying that I want to finish up against the rafters which are under the roof deck (sheathing). You know hand framed, not trusses. An old house ;-)



This is a very low budget job in an old house... my tenant wants to use it as a bedroom and will pay more rent if I finish it (but the rent difference is not that much, so I'm wanting to do the minimum). Insulate, add a couple outlets, sheetrock, one (bypassable) radiator, paint the floor (tenant's choice not mine), done.

Basically, can I just put craft backed insulation up and sheetrock this? Do I HAVE to do some other kind of vapor barrier? Do I HAVE to do a ridge vent?

I'm starting this one on Thursday.

The other one I'm doing (just like this but in another unit) already has sheetrock up (in 24x24 scraps by prior owner. ugh). but I'll be tearing it out redoing it. So I'll need to do the same solution again soon.
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Old 08-28-2012, 04:08 PM   #5
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Re: Vapor Barrier For Finishing Old Attic


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I would vent it. Install baffles and then insulate.
You are going to want to make sure you have venting at the soffit and the ridge.
Or you could have some closed cell insul sprayed in.
What would it likely cost to have closed cell (expanding foam I'm guessing) sprayed in?
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Old 08-28-2012, 04:17 PM   #6
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Re: Vapor Barrier For Finishing Old Attic


Lets see cheep & quick = hot & miserable during the summer with a side of ice dams for the winter... sounds great for a few extra bucks

The only way to do it is to use closed cell spray foam (rafters & gable ends) & you still might have issues because the rafters may not hold enough foam to prevent dew point issues. Time to pull some searches on hot roofs & building science
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Old 08-28-2012, 06:09 PM   #7
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Re: Vapor Barrier For Finishing Old Attic


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Originally Posted by nycphotography View Post
What would it likely cost to have closed cell (expanding foam I'm guessing) sprayed in?
Not much more than baffling, insulating like normal and then having to hire a roofer to ridge vent and possibly add soffit venting.
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Old 08-28-2012, 07:06 PM   #8
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Re: Vapor Barrier For Finishing Old Attic


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Originally Posted by SLSTech View Post
Lets see cheep & quick = hot & miserable during the summer with a side of ice dams for the winter... sounds great for a few extra bucks

The only way to do it is to use closed cell spray foam (rafters & gable ends) & you still might have issues because the rafters may not hold enough foam to prevent dew point issues. Time to pull some searches on hot roofs & building science
What cathedral 3rd floor won't be hot and miserable in the summer? At least I'm looking to insulate... most units in this town are just sheetrock over open rafters

I'm seeing $.30 / sqft for R13 craft faced... closed cell looks like $600 / 400 board ft, which would seem to be 400 sqft @ 1" thick @ R6 (per inch), and that's just materials.

800 sqft (combined wall and ceiling) craft faced r13 would be $240.
800 sqft 2" thick closed cell (R12) would be $2400.

Seems pretty pricey to me... or am I missing something obvious here (like the right source for materials)?

I'm not opposed to doing the right thing... but cost is definitely a consideration. Show me where can I get this stuff for $500 (for 800 sqft) and I'm more than willing to use it.
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Old 08-28-2012, 07:13 PM   #9
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Re: Vapor Barrier For Finishing Old Attic


You can't forget labor to install plus baffles and install.
Add on the cost for soffit and ridge venting and I bet it almost evens out.
I'm not trying to sell you on it, I could care less honestly.
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Old 08-28-2012, 07:22 PM   #10
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Re: Vapor Barrier For Finishing Old Attic


Quote:
Originally Posted by nycphotography View Post
I'm saying that I want to finish up against the rafters which are under the roof deck (sheathing). You know hand framed, not trusses. An old house ;-)



This is a very low budget job in an old house... my tenant wants to use it as a bedroom and will pay more rent if I finish it (but the rent difference is not that much, so I'm wanting to do the minimum). Insulate, add a couple outlets, sheetrock, one (bypassable) radiator, paint the floor (tenant's choice not mine), done.

Basically, can I just put craft backed insulation up and sheetrock this? Do I HAVE to do some other kind of vapor barrier? Do I HAVE to do a ridge vent?

I'm starting this one on Thursday.

The other one I'm doing (just like this but in another unit) already has sheetrock up (in 24x24 scraps by prior owner. ugh). but I'll be tearing it out redoing it. So I'll need to do the same solution again soon.
Bring up the water bed the dresser flatscreen, live load verses dead load?, don't sweat the insulation.
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Old 08-28-2012, 07:22 PM   #11
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Re: Vapor Barrier For Finishing Old Attic


Probably ought to make sure window ,door and stairs to attic meet
egress codes.
Good idea to check with building dept.before you spend
any cash on this project.
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Old 08-28-2012, 07:43 PM   #12
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Re: Vapor Barrier For Finishing Old Attic


Quote:
Originally Posted by 4 seasons View Post
You can't forget labor to install plus baffles and install.
Add on the cost for soffit and ridge venting and I bet it almost evens out.
I'm not trying to sell you on it, I could care less honestly.
Don't think I'm attacking you... I REALLY appreciate your responses. The discussion is very helpful as it guides and my thinking and clears up the fuzzy parts.

As to baffles... I'm putting 3.5" r13 into 2x6 rafters... I have a 2" air gap to the sheathing already. I don't think I'll be bothering with baffles.

Ridge vent, while a PITA, is under $200. I'll do it myself... I just didn't feel like getting up on this roof for this job. Looking closer though, it's an easier roof than I remembered. That leaves soffits and stapling the craft faced, neither of which are a big deal.

I'd love to fill up those 2x6 rafters w/ r36 foam. But unfortunately cost is a big factor in a rental.

But am I finding the right cost figures? Is there some particular supplier I should be considering to find better pricing in 800 sqft quantities? (or even more as I have more attics I may be doing in a few months).
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Old 08-28-2012, 07:54 PM   #13
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Re: Vapor Barrier For Finishing Old Attic


U have to decide if you are doing a hot roof or a cold roof. Either way, there is quite a bit of science involved with both. Just stuffing Kraft faced batts in the bays is definitely not recommended.

If you put 3 1/2" batts in the 2x6 rafter bay and leave a 2" air space and then vent it you will be better off putting no insulation in at all. U NEED TO AIR SEAL THE VENTED SECTION OF ROOF FROM THE INSULATED SECTION OF THE ROOF or you won't really be insulating the roof at all.

Last edited by Morning Wood; 08-28-2012 at 08:16 PM.
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Old 08-28-2012, 07:56 PM   #14
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Re: Vapor Barrier For Finishing Old Attic


Stairs and windows meet fire / egress code (for a single occupancy bedroom).

No waterbeds allowed in any of my units ;-)

Pop Quiz: Is this live load or dead load?

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.


Answer: Depends on if its before or after he crashes through the floor.
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Old 08-28-2012, 08:12 PM   #15
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Re: Vapor Barrier For Finishing Old Attic


What about this?

Ceiling codes:
Generally 7 feet 6 inches high over a minimum floor area of 70 sq. ft. If you have an attic shorter than required by code, you won’t be able to remodel it into living space.


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Old 08-28-2012, 08:55 PM   #16
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Re: Vapor Barrier For Finishing Old Attic


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What about this?

Ceiling codes:
Generally 7 feet 6 inches high over a minimum floor area of 70 sq. ft. If you have an attic shorter than required by code, you won’t be able to remodel it into living space.


I'm meeting the inspector on Thursday. We will see.

But as most attics in this township have been finished at some point in history, it seems unlikely to be enforced.

I don't even need a permit until I move a boiler line or and electric line. As the electric is all there, and the sheet rock is there on 3 units (this one is the only one with open rafters, and even here the gables have been finished at least 20 years ago) odds are I'm ok.
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Old 08-28-2012, 09:32 PM   #17
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Re: Vapor Barrier For Finishing Old Attic


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Originally Posted by nycphotography View Post
This is a very low budget job in an old house... my tenant wants to use it as a bedroom and will pay more rent if I finish it (but the rent difference is not that much, so I'm wanting to do the minimum).
Something I've been trying to figure out ever since you began posting here...

You're a landlord who DIY's his rental properties. How does that qualify you as a professional construction contractor?
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Old 08-28-2012, 10:12 PM   #18
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Re: Vapor Barrier For Finishing Old Attic


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Something I've been trying to figure out ever since you began posting here...

You're a landlord who DIY's his rental properties. How does that qualify you as a professional construction contractor?
It doesn't. It puts me somewhere in between a weekend warrior DIYer and a general renovations guy.

My entire life, everything I've done, I've found the hobbyist groups to not be very helpful for very long, and the pros to be very helpful and informative, provided I just do my best to be respectful and contribute where I can.

That said, if it's truly that private of a club, like god forbid I should learn the secret handshake or something, by all means, throw me out.
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Old 08-28-2012, 10:21 PM   #19
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Re: Vapor Barrier For Finishing Old Attic


Not private but where is the line drawn? Do you make a living by being a paid contractor?

Yes. Welcome.
No. Please visit the DIY site.

Thems the rules.
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Old 08-28-2012, 10:25 PM   #20
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Re: Vapor Barrier For Finishing Old Attic


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That said, if it's truly that private of a club, like god forbid I should learn the secret handshake or something, by all means, throw me out.
You really do come across well, and I'm sorry I have to do it. But the Terms of Service for this site specifically state that you must be a professional contractor, manufacturer or service provider to participate here.

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