Acrylic shower pan with way too much flex... creative ways to get spray foam under there?

[ninian]

Hi All,

We have an upstairs shower we have stayed away from using as there was way too much flex in it when standing on it. It didn't bother us that much until we noticed when someone was standing on the shower pan, something was impacting the ceiling below. I cut out an 8x8 inch square where the impact was and it was the p-trap impacting the ceiling drywall. For now I just installed a spring loaded access panel to cover up the hole that i might just keep in the event any leaks ever happen. That seemed to help a little bit as the ptrap isnt pushing up/down when impacting the ceiling.

It looks like on underside of the shower pan (4 foot "Maax" pan) there is just a thin styrofoam looking layer and from what I can feel, nothing else. There is a decent sized gap (half an inch or so) between that layer and the subfloor around the drain.

My thought is to try and get some window and door spray foam in there. I can probably get a nozzle on each of the 4 sides of the drain from the underside hole I cut out but it will be tight. I could also drill some small holes in the subfloor and try to use a longer nozzle. However, I don't really know how I can possibly get the coverage for all 4 feet of the pan. I figure it doesnt hurt to try and if it all needs to get ripped out eventually so be it (it's fully tiled in a corner). It is brand new (when we moved in 2 years ago) but we have no recourse for getting it fixed from the contractor as it was done before we bought the house. My other thought was drilling some holes in the front of the pan and spraying in that way, however, I don't see anyone doing this online so perhaps a bad idea?

Just wondering if anyone has any ideas? For what it's worth, the base is pretty similar if not exactly like this one: https://www.homedepot.ca/product/ma...er-base-with-square-drain-in-white/1000751523

 

[Reach4]

See https://terrylove.com/forums/index.php?threads/acrylic-shower-pan-ever-silent.95966/#post-690153 for my thoughts.

Mortar sets up stiffer than foam. Also, if some foam expands in place, it can make large forces. Some foam has less expansion force, but that would tend to stay softer.

If this comes up again, you want to put down piles of mortar before dropping the pan, and let those get squished to size.

 

[Sponsor]

 

[ninian]

See https://terrylove.com/forums/index.php?threads/acrylic-shower-pan-ever-silent.95966/#post-690153 for my thoughts.

Mortar sets up stiffer than foam. Also, if foam expands in place, it can make large forces.

Thanks. As I would be doing it blindly, do you just kind of stuff it in the holes and hope for the best? Will it naturally kind of spread out? I can just envision having it all within a few inches of the hole and nowhere else.

 

[Reach4]

Thanks. As I would be doing it blindly, do you just kind of stuff it in the holes and hope for the best? Will it naturally kind of spread out? I can just envision having it all within a few inches of the hole and nowhere else.

I envision making balls that are about 150% bigger diameter than the gap you are filling. The ball would be in plastic, such as Saran Wrap or thin cheap sandwich bag with no zipper etc. Shove up through the hole, and use a finger to push sideways over the wood and under the pan. Push as best you can. Maybe enlist a helper with longer fingers.

I have never done it. I am just envisioning.

To drill the hole with a hole saw without damaging the pan, I think you would just start the hole saw with a pilot drill. Then remove the pilot drill to continue. I think you would want some kind of stop to stop the tool as you break through.

shows using electrical tape as a stop for drilling sheet metal. For wood, could you use thicker layer of tape?

Your photo seems to show a fairly thin subfloor, but it is hard to tell.

 

[Tuttles Revenge]

Mortar won't expand and if you're stuffing bags from the point where the gap is the thinnest you won't be making contact once you stuff the mortar in past the hole.

 

[Weekend Handyman]

I am not a plumber or pro.

I sure wouldn't drill holes through the face of your pan.

If you start drilling holes in your subfloor, make sure you do not drill into your shower base!

If it was my house, I might be inclined not to mess with it. If it causes a problem, you can rip it out that that point. If it doesn't cause a problem, Bob's your uncle.

 

[ninian]

I am not a plumber or pro.

I sure wouldn't drill holes through the face of your pan.

If you start drilling holes in your subfloor, make sure you do not drill into your shower base!

If it was my house, I might be inclined not to mess with it. If it causes a problem, you can rip it out that that point. If it doesn't cause a problem, Bob's your uncle.

You're probably right. Cutting the access panel to stop the impacting of the ceiling and seeing how things looked made me feel a bit better as the plumbing all looks sound. Perhaps we will just use the shower and see how long we get out of it and how things feel.

 

[Weekend Handyman]

You're probably right. Cutting the access panel to stop the impacting of the ceiling and seeing how things looked made me feel a bit better as the plumbing all looks sound. Perhaps we will just use the shower and see how long we get out of it and how things feel.

My father in law has one (Maax I think) ... I would describe it a 'squishy' to walk in (which I have always found odd). Yet, he has had it for years with no problems.

 

[FirstTimeRemodel]

You're probably right. Cutting the access panel to stop the impacting of the ceiling and seeing how things looked made me feel a bit better as the plumbing all looks sound. Perhaps we will just use the shower and see how long we get out of it and how things feel.

How has using the shower base been after a year? Did you end up adding the bags of mortar in?