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Old 11-19-11, 12:59 PM   #21
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I thought the reason why people weren't getting the foam out was because the expansion of the pressurized propellant in the cans would get cold when expanding causing their pressure to diminish and then you don't get it all out. If you heat the cans by immersing them in water you can fight the expansion cooling and get more out.

If that isn't why people aren't getting it all out, then what is keeping them from mostly emptying the tanks? There are thread post upon thread post of people saying they didn't get the full amount out.
You aren't able to change the temperature of the foam in the tanks with hot water or any short term heating. It takes days for the heat to reach the inside. The reason they aren't getting it all out is because they aren't heating it long enough and they aren't shaking it enough. I've never had a problem.

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Old 11-19-11, 01:37 PM   #22
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Oh ok, I didn't think there was that much of a barrier to the heat getting in, if the tank is still filled with liquid rather than foam its insulating quality in the tank could be minimal and keeping the tanks in boiling water could make a little bit of a difference. If you can get it all out of the tanks through a summer heat soak and shaking the tanks then I suppose my concern about it doesn't really exist so much. Thanks for clarifying.
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Old 11-19-11, 02:20 PM   #23
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If you can get it all out of the tanks through a summer heat soak and shaking the tanks then I suppose my concern about it doesn't really exist so much.
I'm not exactly clear on your meaning here. Even in the summer I would still heat them for several days. What might work is to heat them at night and in the day keep them in a closed up car parked in the sun. I can't stress enough how difficult and important it is to heat these things thoroughly enough. Especially the larger kits. Most people don't use the larger kits. They just hire the work out to a spray foam company. I haven't priced the difference so I can't comment there. Most people build a box out of polyiso that can fit a 200' kit and put a bulb in there with a cheap domestic thermostat to keep the inside around 90° f. Set it in there and forget about it for a day or two. Then even in the dead of winter the tanks won't cool down before you use all the foam. I did this to an completely unconditioned rim joist last February. The space wasn't finished yet to there literally was 5° wind blowing on me the whole time. I got all of it out no problem.
Really these kits are over rated. It's extremely difficult to get the mix correct, even for people with $80K gear. There are glimmers of studies emerging showing that most 2 part foam installations aren't done correctly. In the lab I guess it's easier. If the mix isn't right you can get all kinds of issues, including but not limited to: foam that is hard and brittle, foam that will decompose and outgas, foam that is soupy and so on. The studies I have heard of are all based on the safety of the finished product as far as outgassing is concerned, not aout it's performance.
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Old 11-19-11, 02:53 PM   #24
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I suppose there is a good reason why I see professionals who talk about and demonstrate 1 part foam on Youtube when I'm searching for spray foam videos. I'm not sure what options are there. I'm currently looking at using 2" XPS and spraying the outer edge of the 'rectangle' of the rim joist, pushing the XPS into the foam and then foaming the XPS while its firmly held in place using some of the lesser expanding Great Stuff. Not sure if I should go for a pro kit but at this point it seems the cans are the best deal or I should have started with the pro stuff when I was foaming around the windows and doors when the bigger 'cost package' would have made more sense. Then again I'm not spraying a whole room so at this point it doesn't make so much sense to discuss it but I'm thinking ahead as far as 600bd ft kits go as far as making a small super insulated microhouse in the future.
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Old 11-19-11, 06:07 PM   #25
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This is the technique I usually use. It's much cheaper and does the same thing. Don't bother holding it up. Just hammer a single finish nail in the middle of each bay and jam the piece of foam onto it. And you might as well spring for a 200' kit for that. It'll work a lot better than 70 or 80 cans of great stuff. You could do that if all you are after is air sealing but if you want any kind of insulation you'll need so many cans that it would be ridiculous.
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Old 11-19-11, 06:33 PM   #26
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Oh, also, don't bother using the foam as a glue. sure you can do it but you ruin the R value of all the foam you just sprayed turning it into polyurethane glue. Just jam your board on a nail and foam around it. A good tip on this is to try to cut the blocks as close to the size of the bays as possible. At first I did it leaving more than an inch around and ended up spending more money on 2 part foam than I wanted to.
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Old 12-07-11, 04:10 PM   #27
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warmwxrules: I would not recommend using any fiberglass in a basement due to the potential for condensation (unless your foundation happens to be insulated already on the exterior). Also, insulation needs to be in contact with the surface it's insulating so leaving a gap will not result in good performance. Rigid foam is the way to go and it's really not necessary to construct full stud walls either. Here's a diagram I send out to my clients on a good way to insulate basements:

https://docs.google.com/open?id=0BxW...thkey=CMXjveQJ

This is relevant to the rim joist discussion because when you spray foam that area you can bring it down on top of the rigid foam and form a nice continuous layer of insulation.
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Old 12-07-11, 04:38 PM   #28
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warmwxrules:
This is relevant to the rim joist discussion because when you spray foam that area you can bring it down on top of the rigid foam and form a nice continuous layer of insulation.

Bang.
Continuous insulation from the top of the attic insulation to the slab broken only by plates and subfloor.Plates and subfloor are still a big issue but in a retrofit the odds are against you to begin with.
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Old 12-08-11, 05:45 AM   #29
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warmwxrules: I would not recommend using any fiberglass in a basement due to the potential for condensation (unless your foundation happens to be insulated already on the exterior). Also, insulation needs to be in contact with the surface it's insulating so leaving a gap will not result in good performance
Well, I have seen Fibreglass insulated basemen using 6 mm Plastic sheeting as Vapor barrier that lasted over 30 years... being fully dry and still insulating very well. They also use non contiguous 6mm plastic sheeting under the ground line... on the inside of the concrete wall. (DIY, Insulation specialist and contractor jobs alike -- All following the Canadian recommendation by Energy, Mine and Resource Canada).

I have seen basemen insulated with expanse foam (White foam)... Completely ruined after only 6 years... and full of black mildew. (All DIY jobs)

I have seen wall with extruded foam that end-up full of mildew... With gypsum drywall completely wet and deteriorated... with paint pealing. (sometime build by DIY but often by 20$/hours man of all trade construction worker)

If your basement have water/condensation problems... call in the expert or investigate the cause. You likely need water proofing, better drainage around the house or better ventilation. If you are located in the north of USA or in Canada and you have a very well insulated house... you generally need mechanical ventilation (some stirring of the air) or a dehumidifier to prevent the condensation in the basemen -- especially in the spring and early summer when the heating demand is lower.

I never have seen any major problems with sprayed foam insulation... but the fact that all the jobs have been done by a single certified insulation company with a few engineers on payroll might have help tremendously. (all with proper mechanical ventilation mandated by the building code of Québec, Canada)

-------------

Did I replace any fibreglass basemen insulation that was properly done... Actually, yes... following the flooding of a basement -- But, under these conditions, we replace all type of foams as well -- unless we can dry them very quickly (2 days maximum I think) -- and that we can ascertain that the water was not polluted/contaminated.

Essentially, if it get flooded by a river or the sewer, everything but the concrete foundation get replace. The concrete foundation get clean by an Enzyme treatment.

----------

Well, you will have to define touching: In cold climate, a spacing of 1/2 to 3/4 inch between some layers is often use. For example, if you use Aluminium foil insulation as vapour/radiant barrier over fibreglass insulation between 2x4 or 2x6.
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Old 12-08-11, 08:58 AM   #30
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Quote:
If your basement have water/condensation problems... call in the expert or investigate the cause.
Indeed, there is always more to the story. I absolutely agree that things can work out fine as long as there is no moisture problem in a basement. My generalized point was that rigid foam on the wall (not white expanded foam) is the least risky material to use in DIY applications. But if there is any kind of water/drainage problem get it fixed before using any insulation method.

The problems you cited were more to do with external water sources. The issues I've commonly seen are to do with condensation due to high moisture content on the interior condensing on the concrete wall, not being able to dry out due to the vapor barrier and then soaking the fiberglass. You see this all the time behind fiberglass in leaky sill boxes but in finished walls you usually only get to see it after it's too late.

As for the gap: it is appropriate if you can trap air completely so that it becomes part of the insulating assembly or if you are using some sort of radiant reflective coating on one side of foil-faced material. That said, the method of leaving a gap behind a framed wall with fiberglass so that it can dry out is not appropriate: the concrete wall is still cold and can cool the air in the gap, which is, well, not cool. Convective cycling through fiberglass = poor performance and risks condensation issues.

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