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Rim Joist Sealing and Insulation

Post in 'The Green Room' started by velvetfoot, Dec 18, 2008.

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  1. velvetfoot

    velvetfoot Minister of Fire

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    For me I think I've settled on caulking and fitting multiple foam boards cut up with a table saw and covering the edge of the sill (which is sitting on foam) with fiberglass.
    I figure for me it'll be least cost.
    Would appreciate any tips on this method for those who have done it.
    Like, when caulking, do you do the top and bottom joint only? It would seem so since the joists just separate the bays.
    I figure on caulking all around the outside of the outermost foam block.
    I think BeGreen noted already that caulk in a tube can fit in those bays easier than a caulk gun.

    Other methods I've read about:

    -Spray foam contractor
    Cost, + it covers everything on the sill, like wires, right?

    -Fiberglass, unfaced
    That's what my place has now, with no caulking. Don't feel any draft, but I guess water vapor could condense on the rim joist if it got cold enough outside

    -Fiberglass in plastic garbage bags

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  2. smokinj

    smokinj Minister of Fire

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    I used tiger foam all of mine, cost 800 bucks but the job was done in just a few hrs. and no way is anything getting through that stuff
  3. d.n.f.

    d.n.f. New Member

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    Do you have an approximate square footage for that job?
    I just got a spray foam quote and was wondering what that Tiger Foam costs to do the comparo.
  4. velvetfoot

    velvetfoot Minister of Fire

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  5. precaud

    precaud Minister of Fire

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    velvet, just thought I'd pass this on. Just returned from Home Depot and they are now selling 2" Owens Corning Foamular 4'x8' extruded boards (R10) for $19.36 each. That is the same price as 2" expanded boards were last year. This is the first sign I've seen (besides at the pump) of a benefit from lower oil prices...
  6. velvetfoot

    velvetfoot Minister of Fire

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    precaud, are you sure they are 4x8?
    I've only seen the 2x8 in the HDs around here.
    For me the 2x8s can fit in the car, so I don't have to take the utility trailer.
  7. precaud

    precaud Minister of Fire

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    Yep, they were 4x8's. I was stunned because I had payed nearly as much for the equivalent 2x8 from Dow (at Lowes) six months ago. This is the first time the local HD has stocked the extruded. How do you fit 2x8's in a car?!?!
  8. velvetfoot

    velvetfoot Minister of Fire

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    It's a hatch. I can fit at least 10, maybe 12.
    That's a smokin' deal. I'll check it out next time I'm there.
  9. precaud

    precaud Minister of Fire

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    Ah yes, that would work in a hatch...
    With no immediate need, I'm trying to decide if the price is a mistake or this is the 'new normal'.
  10. billb3

    billb3 Minister of Fire

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    I did my sister's raised ranch last Winter using foil covred solid foam.
    Sealed all 4 sides with expanding foam.
    I covered the sealed edges of the cut foam with foil to discourage mice and weather breakdown of the foam.
    She had air / wind / mice infiltration problems.
  11. velvetfoot

    velvetfoot Minister of Fire

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    Well, I'm proceding slowly.
    It was really tough around the electrical panel.
    The area behind the heat manifold will be tough too, but I'm keeping that for later just so I can have the illusion of progress.
    The spray foam would have been great behind those tough areas.

    I had some silicone caulk that was a month past its 'use by' date, and it wouldn't cure.
    Anyway, I switched to latex caulk. I'm doing the wall with the multiple bays.
    I have a 'system' now. Using 4 layers of 2" foam on this wall.
    Pre rip the boards to right height, cut 4 boards to the length of the bay using heavy duty box cutter knife..
    Vacuum out the bay. Caulk the 4 edges.
    Put in first piece. Caulk the 4 edges. Repeat 3 more times.

    The toothpaste tube caulk dispenser gets hard to squeeze for my week hands and it's hard to control, so I've gone back to the gun, and schmeering the bottom innermost wood edges by hand, checking with inspection mirror.

    It'd be so much faster with spray, but I'm gonna see this through.
  12. precaud

    precaud Minister of Fire

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    4 layers of 2" foam is SERIOUS insulation!
  13. velvetfoot

    velvetfoot Minister of Fire

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    It matches up roughly with the foam on the wall.
    In for a penny, in for a pound.
  14. sinnian

    sinnian Minister of Fire

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    Don't seal your basement up too tight. Remember your combustion appliances (burner, gas dryer, etc) need air to work effectively.

    Also, latex caulk will dry out and crack over time. Why not do all of your rigid board work and then get a few cans of spray foam to seal the edges?

    I had my rim joist sills spray foamed a few years ago, and you are right about being able to access wiring and plumbing. Lucky for me I have no plans or illusions to ever finish off my basement.
  15. velvetfoot

    velvetfoot Minister of Fire

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    I didn't know that about latex caulk.
    It says 50 years on the tube, lol.
    I was totally bummed by the non-curing silicone.
    I've been cutting the foam blocks so they're pretty tight.
    Some I even have to pound in with a rubber mallet and a board.
    I really hate working with those foam cans, but am acquiring an inventory of stuff that I'll do at one time.
  16. sinnian

    sinnian Minister of Fire

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    If you use the latex caulk on painted wood and then paint over the caulk it will last, otherwise the oil or whatever seeps into the wood and dries out ~ eventually.
  17. Jackpine Savage

    Jackpine Savage Member

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    I used 2" foamboard, left a 1/4" gap around the edges, and then filled in the gap with spray foam. It went pretty fast and I was happy with the result. I've learned to wear rubber gloves when I play with spray foam :).
  18. velvetfoot

    velvetfoot Minister of Fire

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    Well, I finished one side of the basement rim joist.
    Pretty slow process.
    I put the first piece on a side that is parallel to the joists, so there aren't all those bays.
    I'm optimistic that side will go faster, but I'm still doing multiple layers and caulking.
    Cutting, routing, etc, for wires and pipes also slows things.
  19. d.n.f.

    d.n.f. New Member

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    That is what I was worried about in my situation (the time). I have work, a million home projects, other stuff. For me in this case I am going to pay someone to spray foam.
    Some jobs are worth doing, some jobs are enjoyable, and some jobs are worth paying someone for either due to my lack of expertise or in this case my time.

    Do you notice a difference even with only part of it done?
  20. velvetfoot

    velvetfoot Minister of Fire

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    No. It was well insulated with fiberglass. I feel like I am wasting my time. But, I'm stubborn and will finish it.
    The foam on the wall, on the other hand, is great-notice a big difference.
  21. homebrewz

    homebrewz Minister of Fire

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    Velvet, did I read in another thread that you also insulated your ceiling with fiberglass bats? If so, I'm wondering
    how it worked out for you and if you noticed a difference in the living space.
  22. velvetfoot

    velvetfoot Minister of Fire

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    That's the way it came.
    The basement is definately warmer with the foam on the walls.
  23. velvetfoot

    velvetfoot Minister of Fire

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    Still going slow, but am finding frosty spots, so maybe it won't be a total waste.

    Oh yeah, I found a new knife at Home Depot to cut the foam.
    It's a Stanley Fat Max Extreme, I believe.
    The locking blade wheel and wider and longer blade were improvements over the one I had been using.
    Heavy though.
  24. velvetfoot

    velvetfoot Minister of Fire

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    They don't let us root around at the transfer station, and neither did the last place I lived. I could when I lived in NH but that was back in the '70's.
  25. velvetfoot

    velvetfoot Minister of Fire

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    Almost half done.
    Found a fair amount of ice this PM.
    The fiberglass was unfaced.
    I guess it dries out at some point, but there was a pretty good chunk of ice in there.
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