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Old 08-08-2012, 02:48 PM   #1
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Closed/Open cell foam applications 2 part question


Currently doing about 90% of the work on a complete gut rehab and addition to a 60 year old 2 story 1500ish sq ft home in Kansas City, MO. Here are several details:

- the job is permitted
- I'm installing above average mechanicals
- attic is non-vented
- air handler is in attic
- 50%+ of second story is vaulted
- 2x10 roof rafters
- 70% of the walls are 2x4 construction
- I've read about closed vs. open cell until my head hurts
- I've budgeted 5K for insulation (after rebates)
- there is better than $3K available on rebates etc here in KCMO.
- I've had a blower door test done
- I have 4 insulating estimates thus far, all referrals.

These estimates range 7 to 14K. Basically all unacceptable. And all over the board on what is "right".

My 2 questions are these:

1) I'm seriously considering purchasing 3 to 5 closed cell 600 sq ft kits and doing it myself. Any comments from non-professional souls out there that have tried this? It appears to be somewhat straight forward. I'm sure there's a learning curve. My only reservations come from my experiences with other 2 part throw away mixing guns being tempermental.

2) (Gulp)....... I hate to ask. But is there any personal horror stories out there regarding mold, mildew, damaged rock, etc, etc, etc, from installing either open or closed on the underside of the roof???

If I've not covered certain details, please ask.

Thanks a bunch in advance,
Jules

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Old 08-09-2012, 08:35 AM   #2
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Closed/Open cell foam applications 2 part question


You don't get near the listed yield from the 2 part kits and the foam is not as good as a professional reactor.

Spraying the underside of the roof deck can also be a disaster if you ever have to replace some sheathing.

I would put rigid foam in the rafter bays as that will get you a higher R-Value and will not require replacement if you ever have to service the roof.

Open cell on the roof is vapor open and you can get rot, mold, mildew on the underside of the sheathing if the layer is not thick enough and proper.

Are you going to be finishing with drywall?

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Old 08-09-2012, 10:15 AM   #3
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Closed/Open cell foam applications 2 part question


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You don't get near the listed yield from the 2 part kits and the foam is not as good as a professional reactor.
I've not heard that.

Spraying the underside of the roof deck can also be a disaster if you ever have to replace some sheathing.
All new decking, with 50 year roof. I would hope I don't need to access it anytime soon. But you never know.

I would put rigid foam in the rafter bays as that will get you a higher R-Value and will not require replacement if you ever have to service the roof.
That's a valid option.

Open cell on the roof is vapor open and you can get rot, mold, mildew on the underside of the sheathing if the layer is not thick enough and proper.
And then there's the argument about using closed cell causing dry rot in the decking......

Are you going to be finishing with drywall?
Yes.

I only have one small area (5' x 6' shower area) where I feel moisture may me a problem. Will have to take special care sealing three can lights, fart fan, and a speaker.
Thanks for responding.
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Old 08-09-2012, 03:25 PM   #4
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Closed/Open cell foam applications 2 part question


Rigid board across the rafters because foam in between doesn't change the thermal bridging of the rafters.

I have heard the dry rot issue but I would be willing to bet that you will have condensation issues with open cell before dry rot with closed.
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Old 08-10-2012, 04:01 AM   #5
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Closed/Open cell foam applications 2 part question


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Rigid board across the rafters because foam in between doesn't change the thermal bridging of the rafters.
Agreed. Though attic space is very tight with the air handler up there. Unable to get more than say 2' x 4' pieces installed. In some areas, I'd simply planned to "wrap" the rafters with spray foam. (assuming I could afford to)

I have heard the dry rot issue but I would be willing to bet that you will have condensation issues with open cell before dry rot with closed.
I tend to agree.
In my efforts to secure an insulator, I've taken 4 estimates, and spoken to several others (at recent home shows). And it's amazing how polarized the thinking is. Some will gladly shoot closed cell on the roof. Others absolutely will not.
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Old 08-10-2012, 02:44 PM   #6
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Closed/Open cell foam applications 2 part question


Dry rot is caused by elevated moisture. If you've airsealed the underside of the roof deck completely, wouldn't the only place for moisture to get in be a roof leak, provided the foam is thick enough?
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Old 08-10-2012, 03:43 PM   #7
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Closed/Open cell foam applications 2 part question


Written just for you, LOL: http://www.buildingscience.com/docum...d-roof-systems
Notice Table 3 and conclusions....

Tips: http://www.sprayfoam.com/newsarchive...ils.cfm?id=123

Gary
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Old 08-10-2012, 08:57 PM   #8
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Closed/Open cell foam applications 2 part question


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Dry rot is caused by elevated moisture. If you've airsealed the underside of the roof deck completely, wouldn't the only place for moisture to get in be a roof leak, provided the foam is thick enough?
That's my understanding. Which is also considered to be problematic, as any leaks would potentially never get past the underside of the decking, since the closed cell would trap it.
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Old 08-10-2012, 10:09 PM   #9
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Closed/Open cell foam applications 2 part question


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Originally Posted by GBR in WA View Post
Written just for you, LOL: http://www.buildingscience.com/docum...d-roof-systems
Notice Table 3 and conclusions....

Tips: http://www.sprayfoam.com/newsarchive...ils.cfm?id=123

Gary
I do believe you're right. Written just for me.
Thanks for the link Gary!
Regards,
Jules
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Old 08-11-2012, 10:32 AM   #10
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Closed/Open cell foam applications 2 part question


I know you asked for diy'ers and the kits but i thought i would add one thing that hopefully helps. I had closed cell insulation installed yesterday in my basement. the one thing i did notice is the preasure at which they can install. With their setup they were able to install at a much higher pressure. shooting better into all the gaps andstuff.
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Old 08-11-2012, 01:21 PM   #11
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Closed/Open cell foam applications 2 part question


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I know you asked for diy'ers and the kits but i thought i would add one thing that hopefully helps. I had closed cell insulation installed yesterday in my basement. the one thing i did notice is the preasure at which they can install. With their setup they were able to install at a much higher pressure. shooting better into all the gaps andstuff.
If I might ask. Did they bid the job on sq. footage? Or was it simply a blanket bid?
In my case, three of the four didn't even account for the windows and doors. 29 windows and 4 doors, 2 of which are french double doors. On initial interviews, the so called going rate for the first inch of closed is around $2/ft. In may case, after you remove footage for doors and windows, the figure comes out more like $6-8/ft.
With those numbers, I can be less efficient for decades......
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Old 08-13-2012, 12:35 PM   #12
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Closed/Open cell foam applications 2 part question


no i only had 1 small window. I also had the box sill hit with 3inches of closed cell instead of 2, like the rest of the basement. you must have a TON of windows and doors, very cool.
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Old 08-13-2012, 12:38 PM   #13
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Closed/Open cell foam applications 2 part question


only thin gi can think of is windows and doors are obstacle to go around mask off protect, that may have something to do with it. i am guessing as with alot of thinks the majority of the cost is not in materiel, but in labor.
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Old 08-13-2012, 12:44 PM   #14
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Closed/Open cell foam applications 2 part question


i think mine cost was around 2.30 for everything, 3 inch in box sill and 2 inches in walls, it was around 580 sq feet total, blaket bit, but i only had 1 small window.
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Old 08-14-2012, 06:08 AM   #15
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Closed/Open cell foam applications 2 part question


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i think mine cost was around 2.30 for everything, 3 inch in box sill and 2 inches in walls, it was around 580 sq feet total, blaket bit, but i only had 1 small window.

Well that's reasonable enough.

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