critters and crawlspace question

[NoBanStan]

So my dogs started sniffing around in my closet recently. I figured out why... there's a maintenance grate that goes to the back of our jacuzzi tub. Turns out, whoever installed this thing cut a hole in the subfloor in order to pipe/wire it, but they left it open to the crawlspace. Making things worse, i got down in the crawlspace and realized that the hole through the cinderblock for the AC duct is WAY bigger than the duct itself.. so there's a ton of open air. Doing what they do best, some mice found it and called it home. I set some traps etc and i'm pretty sure i got the critters but now i'm left with the task of... how do i seal this up. I want to do it the right way however.

Any suggestion on materials? I'm not above the labor, it's just the know how. I guess i could cut a plywood section to fill in the gaps and hit it with some kinda foam, but then it's a question on how i attach it. Any thoughts would be appreciated.

[gregintenn]

Can you grout it in with masonry cement?

[NoBanStan]

30 minutes ago, gregintenn said:

Can you grout it in with masonry cement?

it's pretty sizable. I would say at least a foot or two of clearance above the duct.

[peejman]

2 hours ago, NoBanStan said:

it's pretty sizable. I would say at least a foot or two of clearance above the duct.

A foot or two?!?!  Got pics?

I was gonna suggest expanding foam, I had to use that to seal up several spots in my crawlspace.  A foot or two sounds like cutting replacement block to fill the space. Being above the duct makes it harder. You'll probably have to build a frame to support the block.  I'd find a Mason and ask them. 

[Jpoc700]

Without pics brick, stone, and mortar.  If the hole is big.

[NoBanStan]

5 hours ago, peejman said:

A foot or two?!?!  Got pics?

I was gonna suggest expanding foam, I had to use that to seal up several spots in my crawlspace.  A foot or two sounds like cutting replacement block to fill the space. Being above the duct makes it harder. You'll probably have to build a frame to support the block.  I'd find a Mason and ask them. 

 

1 hour ago, Jpoc700 said:

Without pics brick, stone, and mortar.  If the hole is big.

You gents are probably right but I'm going to take some pictures this week.

Foam is what I was leaning towards, or foam block. Just wasn't sure if mice would just chew through it.

[jpx2rk]

supposedly the spray foam is not attractive to chewing rodents, but no first hand experience  on that. 

Can you build a treated wood frame and a piece of treated plywood to seal the hole, then insulate with some of the foam board, paint and your done, assuming you have the carpentry skills, etc.  Picture one of those crawl space access doors you see on houses, just don't make it where it will open unless you need for it to open.  

[pop pop]

If you use foam, make sure you wear rubber gloves. That stuff gets on your hands and nothing, but time, will get it off. It also ruins clothes if you get it on them. Know from experience. Just put my jeans and shirt in trash can last week. Took 2 weeks for me to scratch it off my hands. 

[NoBanStan]

2 hours ago, jpx2rk said:

supposedly the spray foam is not attractive to chewing rodents, but no first hand experience  on that. 

Can you build a treated wood frame and a piece of treated plywood to seal the hole, then insulate with some of the foam board, paint and your done, assuming you have the carpentry skills, etc.  Picture one of those crawl space access doors you see on houses, just don't make it where it will open unless you need for it to open.  

Yeah something like this is what i'm picturing in my minds eye. I definitely won't need a door... though i wish it was because I have to low crawl from the other side of the house to reach it. At best, I can sit upright in the work area. Hopefully I can get out of meetings early enough today to get in there and assess/measure.

[jpx2rk]

4 hours ago, NoBanStan said:

Yeah something like this is what i'm picturing in my minds eye. I definitely won't need a door... though i wish it was because I have to low crawl from the other side of the house to reach it. At best, I can sit upright in the work area. Hopefully I can get out of meetings early enough today to get in there and assess/measure.

IF you need a door, just allow for a couple hinges and a barrel type lock to secure it closed until you need to get inside the crawl space.  

I have a crawl space access door on the low side of my house, about 30" tall by 36 wide, easy for this old fart to crawl thru when needed after I get down on the ground (hard part ).  Two hinges have held it in place with a barrel type lock for almost 20 yrs.  It's made out of the wood siding material and painted, so it has held up well to the weather.  

 

[NoBanStan]

34 minutes ago, jpx2rk said:

IF you need a door, just allow for a couple hinges and a barrel type lock to secure it closed until you need to get inside the crawl space.  

I have a crawl space access door on the low side of my house, about 30" tall by 36 wide, easy for this old fart to crawl thru when needed after I get down on the ground (hard part ).  Two hinges have held it in place with a barrel type lock for almost 20 yrs.  It's made out of the wood siding material and painted, so it has held up well to the weather.  

 

Another door is a bit ambitious for this guy I think. Could, probably. Willing... not so much. Though it does sound more appealing than low crawling the full length of the house in the long term.

[NoBanStan]

Ugh, I hate even asking these questions on a firearms forum... but I'll be honest, i trust you folks more than i do most people.

Anyways, I made the crawl and got some pictures. Again, I'm no construction or AC guy, so this may be totally normal

First set shows where the duct comes in through the foundation, you can see the main gap. Round ducts, square hole. I took a long exposure with the lights off just to show the light leak. As you may ask, the AC unit is firmly against the house and the metal flashing (or whatever its called) has silicone to the exterior . All of that light is actually coming from down low, despite it looking like it's from the top in the photo. It's also not that bright, just a long exposure. I would presume it shouldn't have THAT large of a gap? Again, maybe I'm wrong.

Also took a couple of pictures the hole they cut in my floor under the tub and left open. When i found this, there was insulation over the hole but it had fallen down and the mice were using it as a ramp to get up underneath the tub. I ripped all of that out. Nasty stuff.

[monkeylizard]

The duct opening is normal, maybe a bit larger than needed, but all foundation openings are bigger than the trunk lines going through them. You should NOT be seeing daylight through there. It should fit snug against both the wall and the HVAC and should be sealed with silicone. Check that the sides go down into the dirt so there's no way for critters to get in unless they tunnel under the metal shroud. If not, pack some soil up against the bottom and put some gravel over it to help minimize erosion.

For the plumbing holes, take a piece of cardboard down there and cut a template for each side. Then transfer the pattern to a piece of plywood. A couple of screws up into the OSB above and a short 1x1 screwed into the joist to support the "inside" edge will do it. Run a bead of silicone or caulk around the edges and call it a day. Easy to remove if you or a plumber ever need access to those fittings in the future. Put some silicone around those copper pipes going through the OSB too.

Edited January 11 by monkeylizard

[peejman]

Sloppy carpentry... sadly typical but not as bad as I'd envisioned. 

I'd fix it just like @monkeylizard suggests. 

The expanding foam has been untouched by critters and held up fine at my house for 15 years. Get the low expanding version for masonry and apply minimally. Great Stuff will crack concrete blocks if you go nuts with it. 

[monkeylizard]

P.S.

I would NOT foam at the tub openings. That will make it near impossible to get that plumbing undone if that's ever needed in the future. Basically you're making removable plywood access panels.

[NoBanStan]

appreciate the advice fellas. I think i'm gonna start from the outside first and see if it needs some sealing and work my way inward

[NoBanStan]

On 1/10/2024 at 7:33 PM, monkeylizard said:

The duct opening is normal, maybe a bit larger than needed, but all foundation openings are bigger than the trunk lines going through them. You should NOT be seeing daylight through there. It should fit snug against both the wall and the HVAC and should be sealed with silicone. Check that the sides go down into the dirt so there's no way for critters to get in unless they tunnel under the metal shroud. If not, pack some soil up against the bottom and put some gravel over it to help minimize erosion.

For the plumbing holes, take a piece of cardboard down there and cut a template for each side. Then transfer the pattern to a piece of plywood. A couple of screws up into the OSB above and a short 1x1 screwed into the joist to support the "inside" edge will do it. Run a bead of silicone or caulk around the edges and call it a day. Easy to remove if you or a plumber ever need access to those fittings in the future. Put some silicone around those copper pipes going through the OSB too.

Looks like the guy who did my install left a nice big gap in the shroud when he fashioned it.  Quality work by the AC company i used i suppose. So i'll be sealing that up tomorrow. I'll have to have a close inspection though because the metal frame that the AC unit sits on has a bunch of half dollar sized holes. I will have to inspect to see if they would let varmints wander up under the shroud.

[papa61]

For the sub-floor openings, cut sheet metal to slightly oversize of the opening. Run a bead of silicone around the edge of the hole. Your hardware dealer can reccomend something with tack to it. then self drilling screws around the edges every 4-6 inches. I can't tell if you could do the same around the trunk but if you can, use construction cement to glue it in place. (liquid nails). One option  Good Luck!

 

[monkeylizard]

Those holes around the bottom edge of the HVAC are supposed to be there. They let water out and air flow in. Yes, critters can get through those holes and that's fine. At the rear of the unit closest to the house where the return and main trunk connect, that lower edge should be solid with no holes. Small critters can get around underneath the unit, but there shouldn't be a passage for them to exit to the rear of the unit towards the house.

 

On the subfloor, I wouldn't glue the panels you make, no matter what they're made of. You want to retain easy access to those plumbing fittings if possible. Sheet metal would be fine if you have that laying around. Plywood is easier to work with to me, but YMMV. All you need is any kind of solid material that's easy to attach with screws.

Edited January 12 by monkeylizard

[NoBanStan]

13 minutes ago, monkeylizard said:

Those holes around the bottom edge of the HVAC are supposed to be there. They let water out and air flow in. Yes, critters can get through those holes and that's fine. At the rear of the unit closest to the house where the return and main trunk connect, that lower edge should be solid with no holes. Small critters can get around underneath the unit, but there shouldn't be a passage for them to exit to the rear of the unit towards the house.

 

On the subfloor, I wouldn't glue the panels you make, no matter what they're made of. You want to retain easy access to those plumbing fittings if possible. Sheet metal would be fine if you have that laying around. Plywood is easier to work with to me, but YMMV. All you need is any kind of solid material that's easy to attach with screws.

Appreciate the advice. I'm less concerned about the holes in the flooring tbh and I definitely get the importance of leaving them accessible, even if it's shoddy work.

I wondered if the backside didn't have the holes. I had planned to put a camera in there to take a look. heck, i may just remove the shroud all together soon and and examine everything to be sure.

[NoBanStan]

1 hour ago, papa61 said:

For the sub-floor openings, cut sheet metal to slightly oversize of the opening. Run a bead of silicone around the edge of the hole. Your hardware dealer can reccomend something with tack to it. then self drilling screws around the edges every 4-6 inches. I can't tell if you could do the same around the trunk but if you can, use construction cement to glue it in place. (liquid nails). One option  Good Luck!

 

I'll make sure to use screws long enough to go through the bottom of the tub

[monkeylizard]

17 minutes ago, NoBanStan said:

I'll make sure to use screws long enough to go through the bottom of the tub

Are you sure you're not a professional? That's EXACTLY how some would do it....  

[NoBanStan]

Just now, monkeylizard said:

Are you sure you're not a professional? That's EXACTLY how some would do it....  

What can I say, I'm a
 

[papa61]

sorry I did fail to mention make sure the screws are not long enough to go all the way through the sub floor. It would be great if you came through outside of the tub so you can styep on one barefooted.

[NoBanStan]

1 hour ago, papa61 said:

sorry I did fail to mention make sure the screws are not long enough to go all the way through the sub floor. It would be great if you came through outside of the tub so you can styep on one barefooted.

Maybe I can cut out the middle man and just go through the tub from the top

Jokes aside, I do really appreciate you guys providing helping with this info. What i need to do seems simple now. I was over-complicating it.  But that's how skillsets work I suppose. If you ever need help with cloud hosting or anything compute related, i can do that.