Location of Rim Joist

[Buck Turgidson]

I have about 16" of my home that overhangs the brick/block 1st floor. It is very cold in the winter, and I don't think it is insulated.

The joists run from front to back. An insulation contractor told me that he thought the rim joist was only on the very end, and that there were no cross blocks between the joists. So the thought he could drill into my interior ceiling in the 1st floor, and blow cellulose and fill the cavity that overhangs.

Of the builders in the group, is it typical to not have cross blocks between the joists at the point that they rest of the bricks? If so, that would be great. I had always assumed that there was cross bracing there. I hope I am wrong. Below is a photo of the back of my home.

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[Buck Turgidson]

To be more specific, the floor where it overhangs is the cold spot.

[Dennis]

2x12 and larger joists require bridging. Could be in the form of solid or metal X-braces. Even if solid bridging is installed, the edge joist would support the ends of the joist and the next point of bridging is eight ft. in. Should be no problem for the contractor to blow in insul. Consider going to foamed-in-place polyurethane. Better fill and higher R-value. Wouldn't cost too much considering your only doing about 24 inches.

[hawgeye]

The way it looks, and as it should be, the joists don't rest on the brick. It appears to be brick veneer and joists are actually resting on a stud or block wall that is behind the brick. Anyhow, I really doubt that there is any solid blocking between the joist above the lower floor wall. Should there be, that's debatable, but the point is to find if your house has it. I'd guess that your rim joist is on the very end. Obviously, there is no way of accessing the area, so there's three ways to find out. From the inside, the outside or the top. You could drill a small hole in either the ceiling below or floor above, then stick a long piece of coat hanger wire and poke around to see if there is blocking and/or insulation. Or you could get hi-tech and get one of those flexible lighted gooseneck cameras.

Then what? Suppose there is no blocking and insulation. Poking 20-30 holes in the ceiling to blow in insulation might get it insulated but then you have to deal with all of those holes, unless the insulation guy takes care of that too. If it were me, I'd try to tackle it from the outside. I'd take down that soffit under the overhang, there may be some sheeting behind it but should come down easily, then fill the areas with fiberglass batts. Reinstall the sheeting and the soffit.

[marson]

I'd guess your insulation contractor is right; however, you won't know until you open it up. If an engineer was involved, I bet there is blocking. Dense pack cellulose has the same R value per inch as blown in foam, though it does require a vapor barrier. The foam contractors in my neighborhood have a setup charge for foam, so blowing small areas gets expensive.

[DT]

Looks like vinyl siding? You should be able to remove a piece of the soffit underneath and see what's up there.

[Michael Bulatovich]

I see a tieing headers in that wall at every seventh course. I think it's solid masonry.

It's not required to be over the outside wall below for structural reasons. Depending on the climate it might not be that big a mistake, but in a cold climate, it should be insulated. Having it over the wall, or near the wall below would be nice as a stop.

Be advised that in a really cold climate, this floor will always be colder than the rest, even after insulating it.