Insulating Floor Trusses

[dillon]

I'm looking for opinions on the best way to insulate the space between floor trusses. Someone told me to cut 1 1/2" to fit between the trusses and then caulk around the foam. He said he didn't put plastic over the foam for a vapor barrier, but that doesn't seem right.

I was thinking of fiberglass, bt the space is only the thickness of a 2x4. Either way, putting a vapor barrier over the insulation seems difficult if I want it to seal well.

[jentz]

These floor trusses on a house,Icesahck??

[ishy]

A 2" pass of polyurethane spray foam would do the job. No vapor barrier need. Achieves a less than 1 perm rating.. More expensive but great return on investment, depending on the job of course.. Just my pair of pennies..

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[PurpleFloyd]

A 2" pass of polyurethane spray foam would do the job. No vapor barrier need. Achieves a less than 1 perm rating.. More expensive but great return on investment, depending on the job of course.. Just my pair of pennies..

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+1

[crothmeier]

Net it and blow it with fiberglass insulation.

[dillon]

I just had another contractor tell me to use 1 1/2" foam between the trusses and no vapor barrier. That still leaves the floor truss itself with no insulation.

[Tom7227]

You still haven't indicated that you are building. I would guess an elevated 3 or 4 season porch. That info would help folks narrow down the answers.

[RoosterR]

I think he may be talking about the rim. If truss joists, using thermax insulation is common for this application. No vapor barrier needed with thermax.