What Is This and How Do I Fix It?

[Aikouka]

First of all, this might win an award for the most generic title ever.

When I was removing the drywall, I noticed that a section of the moisture barrier had some fairly large holes and some parts were showing signs of damage. The problem is that I can't really search for how to fix this stuff, because I have no idea what it's called.

Here's a picture of it.

Directly behind that stuff is the brick siding for my house. I had a friend recommend just using expanding foam and sanding it down, but I'm not sure if that's the recommended way.

 

[herm0016]

It's celotex. Buy a sheet and patch it up. Generic name is fiberboard sheathing. https://www.menards.com/main/buildi...-x-8-fiberboard-sheathing/p-1444435987716.htm

 

[mindless1]

Looks like it's just "sheathing board", put on before brick or siding. Since it's nailed on from the outside before the brick was laid, it's a bit of a pain to take off and replace now. I am not a contractor, do not know code in your area.

The correct way to fix this is take down a portion of the exterior wall, brick in your case, remove the sheathing from the outside and put more on then build the brick back up again.

The wrong way, but perhaps not too bad in your case since I assume you're only talking about that one little section pictured, is to mark where the edge of the studs hit on the sheathing board, then pull the two studs on the section you want to replace. Cut out damaged sheathing so that you have both the old and new with some area against the stud to nail it on.

Measure and cut the new sheathing to size, and if its that wood fiber type, or at least on the existing wood sheathing's new cut, use a sealant to waterproof it. Nail the new sheathing to the studs while out of the wall, then put the assembly back up and nail it in.

 

[boomerang]

As herm0016 said, patch it with celotex. Do it from the inside. I would cut away the flared in portions with a utility knife so you have a flat surface to work with. Cut patches oversize and secure with construction adhesive and a few screws to hold them until the adhesive cures. Or, after cutting away the flared in portions, cut a piece the size of the entire void between those studs or a piece that covers all three of the damaged areas and secure it with adhesive and a few screws. The insulation will be compressed a bit more than it should but it will be fine.

That could be damage that occurred during construction but it more than likely was malicious damage from kids. The contractor chose to just leave it be because he knew it would be covered up.

 

[topsecurity]

It is a fiber sheet. Replace it with the new one.

 

[Aikouka]

I'm pretty sure I saw a large sheet of it at Home Depot the other day in their 70% off discount pile. It was probably damaged, but I don't need a full sheet anyway.

In regards to methods to fix it, a friend of mine suggested using expanding foam and then sanding it down. Does that sound like a bad idea? I've also got some 2" foam board that I'm going to be using in a few areas of the wall (along with 1/2" to reach the recommended R13 value). Instead of putting more of the fiberboard up, would it also work if I used foam board (with its adhesive) to create a seal?

To note, you can see the holes in the photo, but I saw a few spots where there are some tears. Would it be best to just put some duct tape (I have actual aluminum duct tape) to ensure these tears don't become holes?

 

[waffleironhead]

You dont want expanding foam as you need to maintain your air gap between the brick and the fiberboard.

If it was me, I would just pick up a sheet of the same material to make a patch. Cut it to fit between the studs and use an adhesive to attach it. Maybe seam tape the edges, but that seems overkill.
If you wanted to go overboard, you could remove a square/rectangle shape of the existing fiberboard and make a stepped patch. Think large square as wide as the studs with a smaller square adhered to it to fit the cutout you made. Use adhesive to attach.

 

[boomerang]

As has been said, do not use foam. Please quit asking about it and ignore that advice from your friend.

If you can use rigid foam in a configuration that would equal the insulation value of batt insulation I would go with that. Any adhesive, regardless of whether your patch is celotex or with foam board I would run vertically. Water should never penetrate the space between the brick and the existing celotex but if were to do so and enter into the wall cavity, running the adhesive vertically will allow it to drain instead of pool on a horizontal bead of adhesive.

And trim off or smush back the blown inward portions so that whatever you use can lay flat.

 

[Aikouka]

If it was me, I would just pick up a sheet of the same material to make a patch. Cut it to fit between the studs and use an adhesive to attach it. Maybe seam tape the edges, but that seems overkill.

To make sure that I'm understanding this correctly, I would cut a square/rectangle that encompasses the damaged area, and then cut out a piece from the new sheet that matches the size/shape. But how exactly do you adhere it? Do you glue around the edges?

If you can use rigid foam in a configuration that would equal the insulation value of batt insulation I would go with that. Any adhesive, regardless of whether your patch is celotex or with foam board I would run vertically. Water should never penetrate the space between the brick and the existing celotex but if were to do so and enter into the wall cavity, running the adhesive vertically will allow it to drain instead of pool on a horizontal bead of adhesive.

If I were to just put the 2.5" of foam in there (two separate sheets, 2" + .5"), would I just cut away the holes or leave them as they are? And to make sure, that would suffice as a seal? I was most likely going to put foam in that cavity anyway or I considered doing just the 2" + half a batt.

 

[boomerang]

If I were to just put the 2.5" of foam in there (two separate sheets, 2" + .5"), would I just cut away the holes or leave them as they are? And to make sure, that would suffice as a seal? I was most likely going to put foam in that cavity anyway or I considered doing just the 2" + half a batt.

As I said, cut out the flared edges so that whatever you put in there can lay flat.

You don't need a seal if you're going to fill the cavity with two pieces of rigid foam insulation. Think about this. There were holes in the celotex since the house was built. There was no "seal". You don't need a seal. We're suggesting construction adhesive in case you decide to patch over the holes first with celotex. The celotex patch would require some adhesive and a few screws to retain it. If you did that, you would be installing batt insulation afterwards or spray foam insulation installed by professionals.

We've got three products in play in this thread that can be described as foam. If you have any more questions you need to make clear what you are referring to because the word "foam" can be interpreted several ways in your post quoted above.

1) Rigid foam insulation.
2) Spray foam from a can. (Don't use this)
3) Spray foam insulation installed by professionals.

 

[Aikouka]

As I said, cut out the flared edges so that whatever you put in there can lay flat.

I think the reason why I was a bit unsure is because if the patch piece is cut to the same size as the part that we cut out, there's nothing for it to lay against as there's a slight gap and then the brick. Essentially, I'm failing to visualize how exactly this piece is held in there.

However, if I can just put up a foam sheet and not worry about patching it with the same material, then we can just save ourselves the headache.

Although, out of curiosity, there's that very small section right next to it. Should there be anything in there? I know they use low-expansion spray foam in the area between window frames and the rough-in. Would something like that be sufficient in there, or is the area so small that it doesn't matter? I wasn't originally planning on messing with all of this insulation ( my task is just to remove the drywall prior to the contractors putting the new stuff up ), but once I saw the state of it, I couldn't ignore it. In some places, the builders never cut the batts to match the non-standard width, so they just shoved it in there, which I read hurts the r-value.

 

[boomerang]

I think the reason why I was a bit unsure is because if the patch piece is cut to the same size as the part that we cut out, there's nothing for it to lay against as there's a slight gap and then the brick. Essentially, I'm failing to visualize how exactly this piece is held in there.

I said in post #4 that you need to cut the patches oversize. They will then lap over the hole and that lapped area is where you can put some adhesive and a few screws. Screws won't hold very well in celotex so just use a few and rely on the construction adhesive to keep it in place over the long haul.

Or, just used rigid foam insulation as you said.

You're thinking about this far too much. This ain't rocket science and you're concerning yourself with stuff that in the grand scheme of things means nothing. You had three holes in that stud cavity that led to unconditioned space and you're worrying about a gap that might cost you $0.06 in total heating costs over the next five years.

Best of luck to you.

boomerang out.

 

[Aikouka]

I said in post #4 that you need to cut the patches oversize.

Ah, yeah... sorry. I'm mixing a few different suggestions in my head, and that made me think about cutting it to the exact size.

You're thinking about this far too much. This ain't rocket science and you're concerning yourself with stuff that in the grand scheme of things means nothing. You had three holes in that stud cavity that led to unconditioned space and you're worrying about a gap that might cost you $0.06 in total heating costs over the next five years.

I asked because I've already got low-expansion spray foam for use around my window and sliding glass door (it currently just has some torn-up pieces of insulation stuffed in the gaps), and I figure that a single window and the door wouldn't use up all the foam, so I might as well not waste it. However, I'd rather not do something if it's "not acceptable practice" or something like that.

Oh, and to note, there was never any insulation in that cavity that had the holes, so it was most definitely an unconditioned space. It makes me cringe a little bit when thinking that I still need to open up a bit more of the wall going over toward the fireplace. That part has the ugly, dated wood paneling, and I'm getting it replaced with drywall. However, since the part in the photo was where the wood paneling began, I'm wondering what other fun, uninsulated things I'll stumble across.