# spray foam and wires in rim joist bay



## Missouri Bound (Apr 9, 2011)

What do you mean "intact"?
You want to foam behind the wires....is that correct?


----------



## mishenka (Jan 7, 2021)

Yes. I don’t want foam covering the wires. Instead I want foam to lay on, to cover the top of the foundation wall.... but currently most of that space on top of the wall is occupied by wires.


----------



## Missouri Bound (Apr 9, 2011)

Is there a gap behind the wires.....as deep as the joist? How far along the joist do those wires go?
How wide is that gap?


----------



## mishenka (Jan 7, 2021)

Give me a moment- will snap a better picture


----------



## mishenka (Jan 7, 2021)

something like this. Sill plate > almost an inch of a wall > insulation > framing(you don’t see framing in this picture). Wires are mostly resting on the concrete wall; some are slightly hanging in that gap between the concrete wall and the strip that holds blanket insulation. This is the best I can describe Of course not all the wall have this situation with wires. Only one where the electronic panel is mounted is really filled with the wires.


----------



## Missouri Bound (Apr 9, 2011)

When homes are built and spray foamed, the wires are impeded in the foam. This does create an issue if you want to rework some electrical down the line.
But if you don't want foam on the wires you will have to pack fiberglass insulation in that gap and live with that.
I was thinking you could put some barrier around the wires, cardboard, plastic whatever to keep the foam off of the wires.
The board in the picture, with the wire stapled to it....is that against the outside wall or is that the "gap" you mentioned?


----------



## mishenka (Jan 7, 2021)

The board wit ha random white wire stapled - is the sill plate. So, I measured off of a sill plate. The gap is from about 2 inches to 3 and a haf inches where the board holding the blanket insulation starts. 

Perhaps I should not even be concerned (as you said) if the wires are covered by the spray foam? Or, temprary pulling wires as far as possibly with a ziptie while I am spraying? Perhaps I am overthinking.


----------



## Missouri Bound (Apr 9, 2011)

Either way.
Here's the thing. You know where the wires are regardless of what you do. In the event you had to get to those wires, which is highly unlikely, you can chip away the foam.
Pulling it away and foaming behind it, in my opinion, would be the best option. You add insulation without covering the wires.
The foam is a draft stopper first, insulator second. I think you are on the right track.


----------



## Bud9051 (Nov 11, 2015)

In the cases I have seen the wires are just buried in the foam. Of course the foam installer isn't going to be the one to deal with digging any wires out if needed.

Here's a thought. If you use caulking to seal all cracks and gaps behind the wires and once dry you cover the wires with tape so they can remain clean. Then spray all you can access without burying the wires.

The foam serves two purposes, air sealing and insulation. The detailed caulking will take care of the air sealing and the small amount of area that may not get a full covering of foam will not affect the overall insulation performance.

Bud


----------



## mishenka (Jan 7, 2021)

@Bud9051 - I actually like this multistep approach. So, do it "by hand" along the side of sill plate in the close proximity to wires, and then simply spray-foam the within the rim joist area. A bit more work this way - but certainly will cover both goals - draft and air stopping and fires not buried within foam. Thanks.


----------



## huesmann (Aug 18, 2011)

If you're worried about "burying" the wires in foam, how about boxing them in with pink foam board, and just spray-foaming the edges of the board to seal it up? If, in the future, you need to access the wiring, you could easily cut away the pink board, rather than having to excavate sprayed-on foam.


----------

