The walls of my basement are studded and insulated with fiberglass. Ceiling is not insulated. Rim joists are not insulated.I would like to insulate the rim joists. From what I’ve read spray foam is the best way to go followed by rigid foam. I’ve seen comments about fiberglass and moisture problems…my town building inspector said this should not be a problem unless the basement is wet or finished. Is spraying worth the cost..besides the fact that I won’t be doing it myself?
Replies
Right or wrong, I caulked each rim/joist bay only because the builder didn't. Then I stuffed it with unfaced r 19 fiberglass and then put in 2 inch foam caulked in place that buts up to the side of the sole plate and runs up between the joists to the bottom of the floor. that will leave you a lot of 1 1/2 x 1 1/2 inch open spots underneath each joist so I cut 2 inch foam and filled them in too.
jim
we insulate the full joist bay at each sideof basement....we make a hollow box with 1" foam
on the end joists we make a 12" hollow box box with 1" foam ....then we blow all of these boxes with dense-pak cellulose
so the entire peimeter is insulated
of course, we also use 1" foam against the walls and stud the walls and dense-pak them too
Rim joist Insulation
Hi Mike, I haven't seen you on-line recently..but I haven't been on-line that much myself recently. Hope everything is well with you. You have been the best source of info. When you do the side boxes (where the first floor joists butt perpendicular to the rim joist) do you pre-build the box and slide it in or slide in the pieces individually (i'm assuming that the boxes are 4 sides worth of foam). Also when you build the boxes how do you attach the sides, top and bottom together? Sounds like a time consuming process.
Thank You
each bay
gets 2 pcs....a bottom and a front...they are all pre-cut and foamed in place w/ gun foam
the front pc has a 1 1/2" hole bored in in it to blow in the cells
on the parallel bays we just use a bottom...foamed in place w/ gun foam, and holes every 3 - 4 ft.