Rim and band joist insulation

When I insulated my rim joists, I cut pieces of scrap 2" XPS a little short (1/4") of what was needed. I then used as little expanding foam as I could to seaql the joints around the rim/plate/ joists and subfloor. I immediately grabbed a pre-cut piece and forced it into the space to let the expanding foam expand/seal and hold the foam in place. If I had extra XPS pieces I used them up. No need to be precise about cutting and fitting and the odd lengths could also be roughly cut to an approximate length.

I also used up some scrap FG batt pieces later, although they probably did not really add any insulation after the 2-4" of XPS, but I did not have to throw them away in the trash.

It is not a fine, precise method, but is certainly effective and has worked well for me on several homes.

The rim is probably the area of the home with the greatest heat/air loss per square foot. This method is certainly many times better than the simple, lightweight, leaky wood stick and FG structure above the foundation that is exposed to the real cold air temperatures. I did not go to those extremes for my basements because the temperature between the soil and the interior is far less than the difference between the wind above grade in cold climates.

Dick

Either way, DIY, and figure in the affordability. You need to stop the air infiltration/exfiltration as said already; from MN;

"The data thus clearly demonstrates that it is not prudent from a condensation management perspective to fill the rim joists with batt insulation, regardless of whether they are covered with a vapor retarder or not. Free circulation of interior drying air in the rim joist cavity, particularly during the summer, would inhibit condensation as well as prevent moisture accumulation. Exterior insulation is effective in controlling winter rim joist condensation but tends to exacerbate summer condensation conditions, particularly in the presence of an interior vapor retarder. With the absence of interior batt insulation and an interior vapor retarder, the negative consequences of exterior rim joist insulation are mitigated. However, especially in retrofit situations, the amount of exterior insulation that can be installed (if any) may not be sufficient to provide adequate thermal insulation (at least R-10). Thus in these cases, the alternative is to install rigid insulation (such as foil-faced polyisocyanurate) flush against the interior side of the sheathing. This still allows air drying of the rim joist cavity but reduces the potential for interior summer condensation by decreasing the condensation surface to the bare minimum of the interstices of the insulation/ sheathing interface. In the winter, the insulation is protected from interior-sourced water vapor by the foil-facing. These considerations are reflected in the recommendations of section F." From: http://www.buildingfoundation.umn.edu/RimJoist/rimjoistphenom.htm

$$$; http://www.buildingscience.com/docu...joist/files/bscinfo_408_critical_seal_rev.pdf

$$; http://www.finehomebuilding.com/PDF/Free/021189072.pdf

$; Fig. 2; http://www.buildingscience.com/documents/information-sheets/crawlspace-insulation/

Gary

So I am doubling the rigid foam, ending up with R14, and leaving the option open to put some batting up there before I do the concrete walls. Walls are getting xps and then 2x4 with bat insulation no vapor barrier.

Had to move some wires, the builder 40 years ago attached some of the electrical to the inside face of the bottom plate. I ended up having to cover the exposed concrete block top and the bottom plate with foam too, the air coming through that was crazy. This way I will have continuous xps from the rim joist all the way to the concrete slab when completed. Using lots of great stuff to get a good tight seal with no air movement.

Next summer I will be gluing xps to the exterior block, installing drainage and backfilling. It gets damn cold up here and I am sick of the shoddy construction the builder did 40 years ago. Everywhere I turn I find shortcuts and mistakes. Doesn't anybody build stuff to last anymore?