Shower Enclosure - No Supporting "Foundation Material"

[sriddle1]

I thought I'd turn to this site for some sensible feedback. I build an ICF House in 2012-2013, I acted as the General Contractor and thought I had everything covered but recently started noticing some flex in my Aquatic Shower Enclosure not to mention the old water spot in the ceiling last night? It appears the water is going under the Drain Assembly's lip that screws down on the surface of the enclosure as I stand on the base and it flexes downward creating a gap for water to escape. Discovery - Plumber did not install any "Foundation Material" when setting the unit as required in the Aquatic Install Instructions and as verified when I removed the base trim from the adjoining wall and cut the drywall inspect, thank goodness my base trim is 7-1/2 inch high and the cuts are hidden. Because of access limitations I'm searching for a solution.

Reading the Jacuzzi Bonaire Shower Stall Installation Instructions: "Materials that may be used are a floor leveling compound, mortar, plaster or minimal expansion structural foam having a density of a minimum of 5 lbs./cubic feet. I would like to pursue the use of foam if possible. Also, I found a Foam Dispensing Gun on the HDepot Site with a 23 inch long tip giving me a good reach. I'm looking for a brand of low expansion foam that meets the Jacuzzi Specs for hardness/structural support. Blogs also recommend placing plastic backs under the unit then filling with the foam so it doesn't stick to the sub-floor or shower enclosure just in case the enclosure is removed in the future and future noice considerations. A Big Warning/Red Flag , many Blogs indicate unless the right foam is used it will breakdown and compress over time resulting in voids, movement, and full-circle I go. As another thought I also read lots of people recommend USG's product called Structo-Lite as a Foundation Material but I don't know if I could use some type of mechanical a pump with a small hose to get it in there, we're talking a 2 inch void. Any Technical Recommendations/Suggestions would be appreciated.

 

[dave1949]

Sounds like a good diagnosis.

Another material to consider is blocks of high density foam like that used for blocking heavy stuff for shipment. Maybe you could find some of that and manage to stuff it in around the drain.

Or, there is this: FOAMULAR® 1000 High Compressive Strength Rigid Foam Insulation

2" thick foam sheets for load bearing applications.

After you get some support around the drain, some plumber's putty between the tub and the drain flange should help too.

 

[dave1949]

As an observation, I installed a Jacuzzi tub in our last house that required the plaster bed for support. It was a large two-person tub with a good bit of slant in the bottom, plus I wanted a finished height for the tub taller than the tub depth. What a project. I built a plywood ramp that would leave ~2" of bedding space between the ramp and the tub bottom, mixed the plaster, spread it, seated the tub in the plaster, etc.

It worked fine but there are tub brands that come with integrated bottom support that make all that bed building unnecessary. I would look for that if I had to do it again.

 

[sriddle1]

UPDATE from DOW, not sure what this means, I'll have to investigate how it's applied but for others encountering this situation here's what they said:

"GREAT STUFF™ sealants use moisture in the air to cure. They are designed to fill small cracks and gaps. The foam does not cure properly if it is used to fill large voids unless it is put down in layers and allowed to cure before the next layer is applied. Do not use GREAT STUFF™ sealants to fill enclosed voids such as behind drywall or under tub surrounds. Instead of using GREAT STUFF™, consider using Dow FROTH-PAK™ Class A polyurethane foam insulating system in cavity applications.

FROTH-PAK™ is commonly used in this application to fill a void under a pool or spa to stop flexing, provide structural support, insulate and reduce vibration. However, installers should be aware that the foam will expand 3 to 5 times and will exert a lot of pressure on the pool or spa. Use a brace to secure the pool/spa or fill the pool/spa with water to add weight to keep the pool/spa in place when foaming. It is always recommended to check with the local building code official to confirm the use of FROTH-PAK™ in these applications.

 

[sriddle1]

It worked fine but there are tub brands that come with integrated bottom support that make all that bed building unnecessary. I would look for that if I had to do it again.

dave1949, Thanks for your thoughts, I only wish I had the access to do what you suggest without doing a complete demo however, drywall and trim up and finished and Dreamline Glass Doors installed. I'll have to go in from the side, hopefully with a Foam Dispensing Gun, Dow says their Great stuff Pro Gun 14 has the option of 26 1/2 inch barrel length. That has now been replaced with the option of a 40 inch barrel. Thats good news for me if I can find the right foam to use.

 

[Raised on a Deere]

As an observation, I installed a Jacuzzi tub in our last house that required the plaster bed for support. It was a large two-person tub with a good bit of slant in the bottom, plus I wanted a finished height for the tub taller than the tub depth. What a project. I built a plywood ramp that would leave ~2" of bedding space between the ramp and the tub bottom, mixed the plaster, spread it, seated the tub in the plaster, etc.

It worked fine but there are tub brands that come with integrated bottom support that make all that bed building unnecessary. I would look for that if I had to do it again.

I built a housein1973, lived in it 27 years and now son lives in it so I have had a chance to see how some of my bright ideas worked out. On the tub I had been observing flex in the shower floors when visiting friends living in new homes. I grew up bathing and showering in a cast iron tub. The movement just made things feel cheap. Also I was inexperienced builder, just winging it. Pressed for time to get things done and move on to next task, I did what Dave 1949 did. I mixed some buckets of concrete and poured it in a frame made from scrap wood pieces and set the shower unit in, careful to not press down on any one area in the bottom but gentle pressure while wiggling and satisfied my self that the bottom had not been flexed upward anywhere, cleared the drain and supply line access area, nailed the unit to the walls and wondered how this was all going to turn out. I worried that there would be a crunchy feeling stepping into the shower as it aged, perhaps cracking and popping, and maybe even stress crack due incompatibility of thermal expansion rates. In fact, it has always been perfect. Just visited with my son this past weekend and the shower unit is as solid as could possibly be, that's 41 years of heavy use.

BTW the instructions with the shower unit said it was self supporting and that warranty was void if it was set on anything other than a flat solid surface. I laughed at the idea of a worthwhile warranty action and proceed to do what made sense to me knowing that some times I learn an expensive lesson. This one still brings a smile every time I use it because all the builders were telling me it was a waste of time, they did nothing but nail it in.

 

[Cord]

It sounds as the mfr. wanted the shower pan to be "mud set". I usually mud set mine, even when they don't require it. Basically I mix a couple of bag of mason mortar and throw it on the floor. Pile the mortar high so the shower pan displaces it. Set the pan and tap it into position while leveling it. You can not pull the shower back up, so keep working it down without going too far.

It sounds like you can see the bottom of the shower through the drain hole in the sheathing. A closed cell expanding foam (Great Stuff) might be a good option for you. You could try the max expansion, but don't get too crazy or you could lift the pan. I've used a rubber hose in the past to extend the nozzle for those hard to reach places. Waiting a day between layers will help you control the pressure of the expanding foam. If you can't wait, a exceedingly light mist of water to ensure sufficient moisture to cure.

The Frothpak stuff is very difficult to find and obscenely expensive. See if you have a ABC supply nearby, they'll sell to you if you don't have an account.

 

[dave1949]

I was hoping you had enough clearance from the end or side to slide some material in.

If you use the spray foam, maybe you could disassemble the drain itself, leaving the drain pipe in place. Block the opening in the pipe, then spray the foam around the pipe. The hole in the pan is probably bigger than the drain pipe outside diameter. Maybe enough to get spray wand in there. Not a total solution but it could help get the foam into the area.

You can trim out any foam that expands into the drain hole. I would tape down a plastic cover inside the floor pan first in case the foam bonds to the pan floor.

 

[sriddle1]

Found the FROTH PAK on-line, their #12 Kit (12 cubit feet coverage) runs about $40.00. As DOW's Technical Support Email to me indicated, ANY Great Stuff Products, regardless if it the "PRO" Series or not, cannot be used, it is not designed to handle any structural weight and will eventually break-down as the base flexes "CRUNCH". I have to laugh though, you look on-line and everyone recommends their "Big Crack" Blue Can Foam...those who go that route are in trouble. I did contact Jacuzzi's Techncial Support Team, they will not recommend any brand meeting thier specs and simply re-state it must have a minimum density of 5 lbs./cubic feet, a circular conversation for sure.......... To re-cap, a good 3/4 subfloor under the shower enclosure, properly framed as per rough-in, hole for plumbing A-OK.......Everthing done perfectly except no Foundation Material as the unit was set. As the General contractor you can't be in all places at once so that was missed although stated to follow all mrf instructions, they were even taped to the unit but that's spilled milk and I'm not going to tear the unit out and so the search for a solution. Becasue the unit is totally enclosed and finished-off (installed in 2012) I removed the base trin from an outside wall, cut the drywall up 6 inches between the studs, I can see the gap along the bottom of the enclosure......... Turns-out the FROTH PAK will probably not work, although it has a good pressure stream there are no extension available for the nozzel to allow me to stick it in say 24 inches and shoot small batches.... Onward and Forward as they say..........

 

[dave1949]

I have one more idea. Not a great one, but ...

Can you work on it from the bottom? It would be less cost and overall disruption if you could take down the (sheet-rock)? ceiling below the shower. Drill foam shooting access holes in the sub-floor (carefully to avoid hitting the shower pan), spray the foam in, repair the ceiling.