Rim Joist Has Nails Sticking Out - Can't Fit Foam Board? - Insulation - DIY Chatroom Home Improvement Forum
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Old 11-18-2019, 10:31 AM   #1
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rim joist has nails sticking out - can't fit foam board?


hi,

went to insulate the rim joist and saw nails sticking out. IDK if using foam board makes sense. The the nail will pretty much poke hole on the board as i push against the rim.



Is foam insulation my only option?



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Old 11-18-2019, 10:39 AM   #2
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Re: rim joist has nails sticking out - can't fit foam board?


Why can't you take a Dremel with a CUTOFF wheel, and remove the nail?

There are other options , but the rigid foam is easiest.

Spray foam, even batts cut to fit, but I would just cut them off.

Even Side cutters ( Dykes), would work to cut them off.


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Old 11-18-2019, 10:43 AM   #3
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Re: rim joist has nails sticking out - can't fit foam board?


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Originally Posted by de-nagorg View Post
Why can't you take a Dremel with a CUTOFF wheel, and remove the nail?

There are other options , but the rigid foam is easiest.

Spray foam, even batts cut to fit, but I would just cut them off.

Even Side cutters ( Dykes), would work to cut them off.


ED

you cant cut them out? is it structurally safe to do?
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Old 11-18-2019, 10:49 AM   #4
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Re: rim joist has nails sticking out - can't fit foam board?


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you cant cut them out? is it structurally safe to do?
You only remove the extruded part, not the whole nail.

Hell, even bending them over with your hammer will keep them from piercing your foamboard.

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Old 11-18-2019, 03:10 PM   #5
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Re: rim joist has nails sticking out - can't fit foam board?


I don't see the problem with poking the foam board onto the spike of the nails. What will it hurt? It won't poke through the total thickness of the foam board. I may not be understanding the full problem, here.
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Old 11-18-2019, 04:48 PM   #6
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Re: rim joist has nails sticking out - can't fit foam board?


I am with Larry ---- " nails - so what ? "

But to answer your question, XPS or EPS that is caulked on the periphery is much better than fiberglass because it is also an air seal, not just insulation.
Fiberglass would need a vapor barrier, but that is very difficult to make air-tight on rim board.
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Old 12-06-2019, 10:32 AM   #7
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Re: rim joist has nails sticking out - can't fit foam board?


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I don't see the problem with poking the foam board onto the spike of the nails. What will it hurt? It won't poke through the total thickness of the foam board. I may not be understanding the full problem, here.
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Originally Posted by SPS-1 View Post
I am with Larry ---- " nails - so what ? "

But to answer your question, XPS or EPS that is caulked on the periphery is much better than fiberglass because it is also an air seal, not just insulation.
Fiberglass would need a vapor barrier, but that is very difficult to make air-tight on rim board.

here is beginner's thought process, if you punch hole on 2" foam board with nails, are not you technically reduced the R value since you are creating a hole?
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Old 12-06-2019, 11:24 AM   #8
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Re: rim joist has nails sticking out - can't fit foam board?


Bend them so t5hey are straight out or back flat against the rim and push the foam board into place. They will not significantly affect the r-value of the foam. If too long such that they would pass all the way through bend or cut those.

The benefit of rigid foam is to prevent inside air from reaching a cold surface where the air could cool and form condensation.

Technically you also need a layer of fire resistant material covering the rigid foam. Limited area is sometimes not a problem. A few inches of rockwool might work.

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Old 12-06-2019, 11:58 AM   #9
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Re: rim joist has nails sticking out - can't fit foam board?


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Originally Posted by jackallis View Post
here is beginner's thought process, if you punch hole on 2" foam board with nails, are not you technically reduced the R value since you are creating a hole?
You are not creating a hole, per se', you are creating a piercing. The nail will be encased in the foam board or slightly protrude from it.

At worst, you will loose your thermal break by that nail.

As others have suggested, cut it off, nail the nail down, or don't worry about it.

Or skip the foam board and go with rockwool. (Formerly known as Roxul.) It is very dense (not as dense as foamboard, but it is fire proof, vermin proof and resists air movement much better than fiberglass. And you don't have to cover it as you should foamboard.
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