DIY spray in foam insulation


I started replacing the siding on a pickup bed camper and when I got the siding stripped down I found the fiberglass insulation was not in the best shape. I was thinking of trying one of the DIY kits of polyurethane spray in insulation instead of putting back more fiberglass batting. Ive read the brochures but I wondered if anyone has had any first hand experience using it. It looks to me like you just keep spraying in thin layers , let them expand and set then do it again to you get the thickness you want. I was looking for the gotchas. My plan is to set the tanks up on a work table with casters and have the wife push it around the camper following me. Hopefully once we start we can just keep going until its done. Since the framing is 2 X2 I figure two passes should be enough.
Jimmie
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On Tue, 20 Oct 2009 13:09:21 -0700 (PDT), JIMMIE

I redid mine (camper trailer) with foil backed rigid urethane foam panels, cut to fit and glued in with panel adhesive.
Cheap, easy, and effective.
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snipped-for-privacy@snyder.on.ca wrote:

To the OP, visit RV.NET and go to the truck camper forum, these rebuild questions appear frequently and there is a lot of expertise there.
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On Tue, 20 Oct 2009 13:09:21 -0700 (PDT), JIMMIE

re: "gotchas"
There are minimal expanding, and triple expanding types. Pick the proper one.
Triple expanding foam, used around a door frame or windows might cause the frames to bow.
http://www.greatstuff.dow.com/products/index.htm
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And minimal expanding doesn't insulate as well.
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Knew someone who did that. Not happy.
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On Wed, 21 Oct 2009 09:28:02 -0400, Stormin Mormon wrote:

Makes me think of http://www.diyfaq.org.uk/humour.html#foam
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The stuff is great but a pain to work with. It expands with a very lumpy surface so it is impossible to get a flat surface. You have to trim it down to get it flush with the 2 x 2's. You get large hills and deep valleys which means you go back to fill in the valleys and then you end up with a lot of hills to trim off. I got a trimmer from a friend but I don't know what it is called. It was a lot of work to do it manually - sort of like a coarse sanding/grinding job. I saw a TV show where they used a power trimmer it seemed to be fast and simple.
If you want to save a lot of work you could put in the inside panels partway up and spray down into the space. The problem with this is that the foam expands instantly with enough force to blow a panel loose. You have to spray with the trigger down for just a split second and keep the nozzle moving very rapidly. You add thin layers into the space to keep it from being blown apart. Saves a huge amount of trimming. I was helping my Dad insulate a small hot tub shed. We put cheap panels as horizontal strips about 18" high, insulated behind them and then put good panels on top for a finished surface. The foam acts like a good glue and we at first tried to get the cheap panels off to re-use them but they just stuck to the foam and tore and were too much trouble to remove so we left them.
We made three practice boxes to practice spraying down into a space and learn the trigger action and nozzle swing that wouldn't blow the panels apart. First two trials we blew the panels apart but by the third try we figured it out. The top space we had to just spray it on and trim it off - took a lot longer to do the top 18" strip than the rest of the walls. Ceiling was easy because we sprayed from the top before nailing on the roof sheeting and we left the foam rough.
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Why, I don't think you are going to gain anything and its going to cost a ton of money over just using rigid or just more fiberglass.
It may have a higher r value but overall its not going to make much of a difference.

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I rebuilt one before and had it sprayed by a professional insulation contractor who happened to be working in the neighborhood. The spray foam adds a lot of strength to the camper. It also seals the heck out of it. If water gets under the siding this time it just wont matter. The best price to have it done is $500 I could DIY it for $300.
Jimmie
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