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Rifraf
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# Posted: 9 Jan 2012 11:03am - Edited by: Rifraf
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Soon I will have to make this decision.
My internet research has varied and so I cant trust those facts. If I call foam installers naturally they boast the foam, same for cellulose installers. I have a local cellulose installer near my cabin, the nearest foam installers will charge me a premium for such a small job.
Can anyone verify if this information is accurate ?
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Martian
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# Posted: 9 Jan 2012 11:44am
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Look at the DIY foam kits. They run about $1/sqft for 1" of foam; roughly R-6. I like foam, but used fiberglass batts in the walls and 18" of blown fiberglass in the attic. The local box store let me use the equipment free when buying the insulation.
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adakseabee
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# Posted: 9 Jan 2012 02:24pm
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Rifraf.
I have always thought that if something doesn't feel right, look right, or smell right, it is NOT RIGHT. Based on the information provided in the URL you provided, there are sufficient examples provided of disaster during and after application of spray foam or with products containing foam, that I would not touch spray foam with a ten foot pole. Call me old-fashioned, but I refuse to take unnecessary risks. The R-value of cellulose is comparable to spray foam, if not greater than spray foam, is cheaper, and is greener. I'd go with cellulose.
- Adakseabee
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soundandfurycabin
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# Posted: 9 Jan 2012 03:21pm
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If you're willing to do it yourself, you could fit rigid foam board between the studs/rafters and seal with canned foam or an inch of foam from the DIY kits Martian mentioned.
If you'd rather have someone else do it, just get bids and go on price. Both are good options. Don't listen to paranoia from the cellulose and spray foam manufacturers about each others products. Both are building code approved and safe for residential use.
Frank
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TomChum
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# Posted: 9 Jan 2012 03:34pm
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If you use foam check that it's safe to breathe that stuff all night long over the coming years. If it bulges your walls out it's going to be no fun at all. Better check if it's OK with a 24" span.
A lot of effort to get the last few percent will never pay off. If fiberglass batts get you within 20% of "the best" insulation, I would choose batts, they are simple cheap and reliable.
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SheldonDesigns
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# Posted: 9 Jan 2012 05:00pm
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As in almost all cases, the horror stories with any material mostly come from faulty installation and/or preparation.
There is one caveat with spray foam (i think closed cell), even if is installed correctly. When the foam completely seals a cavity, it can also block water that is leaking from the exterior.
Once this gets inside, it can begin to rot the structure without any interior signs that there is a problem... until it is too late.
For this reason, I will only specify an open cell foam that will transmit the water much faster, so you know you have a problem, or preserve the air flow above the foam so the water is not held against the structure.
And I agree completely with Tom... the 80-20 rule definitely applies.
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bobrok
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# Posted: 9 Jan 2012 05:10pm
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Anyone have any info on dense-pack insulation?
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MtnDon
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# Posted: 9 Jan 2012 06:45pm
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My overall preference for wall insulation is the dense pack wet blown cellulose. I would have used it instead of fiberglass batts if I could have found an installer who would have come up the mountain for a reasonable price. So in part the choice of what type to use is dependent upon what local installers you can find. Most of these don't work well as DIY.
I know someone who did his own spray foam; After he was done he said he would not do it himself again.
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Rifraf
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# Posted: 10 Jan 2012 03:06pm - Edited by: Rifraf
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Can anyone here clarify something else for me regarding insulation?
My cabin has no ridge vent or vent of any kind in the ceiling/lofts. Just plywood over the framed roof, and shingles on that.
No real ventilation where the roof pitch meets the side walls either.. I suppose very small amounts of air can probably pass in via the grooves in the t111 siding at that point , but thats it.
Sooo, if I have expanding foam blown in the ceiling , do I still need to have some sort of air passage installed first ? I dont see the point in this unless I also create entry and exit points for that air.
Whats the best option for me here ? just blow in the expanding foam with no air passages ?
I guess I have another question , the dense wet cellulose stuff.. can it even be used in vertical spaces? Is the wet portion of it a glue ? and if I use cellulose instead of expanding foam, how would you answer the previous question regarding air passages
Thanks in advance!
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MtnDon
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# Posted: 10 Jan 2012 03:27pm
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Foam in your ceiling has the advantage of sealing the air out. The foam adheres tightly to the OSB and seals air from touching the cold OSB. Keeping the air from reaching the OSB means moisture can not condense on the foam. The foam will be warmer than the OSB so moisture will not condense on the foam. Sometimes a roof with 12 inch rafters will have two inches of foam allied and then the rest done with batts or cellulose. I know someone who had the 12 inch rafters filled with spray in foam; Alaska.
Wet blown cellulose is used in walls. Sometimes a small amount of adhesive is added to the water mist. It is sprayed/blown in place then "shaved" to the stud face. Kind of messy and needs a pro.
Cellulose can be used in a cathedral ceiling as I understand it. It can be done without any venting but there may be a minimum thickness of the cellulose to allow that. Not sure but something rattles around my head about that. Check with the installers and also do some research on manufacturers websites.
If you have only 2x4 or 2x6 rafters the sprayed in place foam might be the best one as it will seal humidity laden air away from the cold OSB for certain.
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Rifraf
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# Posted: 10 Jan 2012 03:37pm
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Hey , thanks again MtnDon.
What would happen with the foam in the ceiling if the roof leaked ? would the water get trapped just below the plywood and rot the ceiling ? or would there be adequate air passage through the plywood anyway to dry it out?
Sorry for all the questions, ill pick the brains of my installer too , but some "pros" make me feel like they will say whatever lets them do the work get paid and get out fastest, I feel I get an unbiased and straight forward answer here.
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MtnDon
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# Posted: 10 Jan 2012 05:22pm
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That is a good question. There are two types of foam, one is called closed cell and the other open cell. Open cell is similar to a sponge. Water from a leak in the roof can seep through it and eventually reveal itself in the ceiling covering. Closed cell does not let water enter the foam. So a leak above may not be readily seen. That's a point in favor of using open cell foam. Open cell foam on the other hand does not have quite the same R-value... it is slightly lower.
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bobrok
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# Posted: 11 Jan 2012 01:42pm
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Cellulose can be used in a cathedral ceiling as I understand it. It can be done without any venting but there may be a minimum thickness...
I recently had one of those home energy audits on my older house. I have blown in rockwool insulation from the old days and it had settled inside the walls to the point where the infrared camera actually picked up these rather large gaps. In addition to this the camera also found other voids that were leaking in cold air. I also have 45° angles on the second floor exterior ceilings/walls with only the thickness of the rafters between inside and out.
The company doing this testing offered the dense pack as a solution to just about all of my problems. They said they would fill dense pack in the wall cavities and actually compress the old rockwool. They also said they would remove the rockwool from the upstairs sloped ceilings and blow in dense pack with no vapor barrier or provisions for air flow.
It sounds almost too good to be true that dense pack can be the cure all for my house and I have my doubts. Of course we're looking at old, existing construction and the cost to open it up vs. cramming in more insulation.
I'm wondering if anyone has done this to an older house. Now with new construction they make it sound like its the best thing going, especially the no need vapor barriers and ventilation.
Truth? Or sales pitch? What do you think?
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MtnDon
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# Posted: 11 Jan 2012 02:59pm
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Truth. They drill holes in the stud bays near the top and the bottom. Then blow in cellulose. It can make an amazing difference.
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ErinsMom
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# Posted: 11 Jan 2012 06:54pm
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MtnDon,
You are a wealth of knowledge that is much needed. God bless.
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bobrok
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# Posted: 12 Jan 2012 09:09am
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Truth. They drill holes in the stud bays near the top and the bottom. Then blow in cellulose. It can make an amazing difference.
What I don't understand, though, is that there is no mention of a vapor barrier. This flies in the face of everything I have ever known about proper insulation, including the moisture leakage addressed above. Is there something in the dense pack mix that seals against moisture infiltration and also creates a vapor barrier.
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Just
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# Posted: 12 Jan 2012 09:52am
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Quoting: bobrok vapor barrier
I asked that question when i did one years ago .The contractor told me I would be ok as it was a older home and it had many coats of oil
based paint that would act as a moisture barrier. I still own the place
and he was right. Not sure in a new build with water base paint ?
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bobrok
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# Posted: 12 Jan 2012 10:18am - Edited by: bobrok
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Older home and it had many coats of oil based paint that would act as a moisture barrier.
I was also told this many times, and i suppose with a 1934 built house i have a few coats of oil as well, but being the unabashed cynic that I am I am always wondering if they are just telling you what you want to hear.
Just: I have another question off this topic that I would like to ask you. Could you send me an E-mail so we could communicate? Thanks & appreciated!
offgridfanatgmaildotcom
Bob
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MtnDon
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# Posted: 12 Jan 2012 10:19am
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Remember a vapor barrier on the inside wall is not applicable to all climates; many of them but not all.
I'm fuzzy on the numbers, but packed dense enough and to some minimum thickness cellulose is supposed to act like a vapor barrier IF I recall correctly. I'm short on time this AM. Search.
There are special latex primers that have a high non permeable rating. They work well in cases with existing walls. For new construction, if you need a vapor barrier (cold climate) I figure it is more of a sure thing to use a plastic barrier under the drywall/whatever.
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