View Full Version : Shower base with styrofoam filler!

11-19-2005, 07:41 AM
I am replacing a shower stall that I installed about 10 years ago. The base developed hairline cracks in the base after about 5 yrs of use probably because the 3/4" plywood subfloor was not supported adequately enough causing the shower base to flex and crack (the shower floor rests on the plywood). I just bought a replacement round shower enclosure kit and to my surprise, the filler in the base is made of styrofoam! I'm thinking the styrofoam will be compressed with use and allow a lot of flexing of the shower base and it will fail even sooner than 5 yrs. I am considering removing the glued styrofoam and replacing it with something stronger but since the base slopes from the perimeter to the drain hole, it is not too simple a task. The styrofoam is about 1" thick around the drain and 1 3/4" thick at the perimeter. Has anyone dealt with a problem like this and come up with a good solution?

Gary Swart
11-19-2005, 11:49 AM
I'm not a pro, but I have done some shower installation, and it's a subject often talked about on this forum. This is the first time I've heard of this, and I too am skeptical. The method I am familar with is to put down a mortar base. It doesn't have to be absolutely soild, just so the honeycomb is supported in several places. Many of the pros that frequent this forum don't respond to posts on week-ends, so perhaps some of them will give you a more informed answer.

11-20-2005, 02:48 PM
I'd leave the foam alone and go for it. Now, if the floor is not flat, you could put down some mortar there in addition to fill in the voids.

When you have a structure that is relatively flat, the pounds/sq in is quite small - the foam is pretty stiff. One company, www.schluter.com and others make foam shower pans, but they are meant to be tiled. Still, the tile doesn't crack, so your floor shouldn't either (if done right). Note, if the thing does NOT sit flat on its own, add something to ensure constant support, eithersome more foam or mortar.

My unprofessional opinion.

11-20-2005, 04:31 PM
Gary, by pros, I am guessing that you mean licensed plumbers. That would be great if one who has seen this problem would respond but I'm thinking that probably most plumbers would not be involved with a DIY type shower kit (just under $500 from Home Depot). Jim, I would agree that there would not be much psi on the foam if the base is rigid and could spread the load over a wide area but in this case, the less than 1/8" thick pvc base is very flexible and would transfer the weight of a heel, for example, directly to the foam and compress it. The Styrofoam is more dense that the packing type foam but I can easily squeeze the foam between my finger and thumb and compress it a little. The previous shower base cost twice as much 10 yrs ago and is much more heavy duty but the base started cracking in about 5 yrs. This replacement kit has a warranty of 3 yrs and I suspect, like a car battery, it will fail on the expiration date. :) I am thinking of ripping out the foam (just under the flat part of the base, not the high rounded front piece) and then use a floor leveling mixture (mixed with foam peanuts to keep the density down?) then pour into a perfectly level upside down base until it sets. Well, I dunno...it may be a half baked plan. I'll wait a few more days and see if someone out there has run into a situation like this and has a better solution. I'm really PO that someone could come up with a poor design like this. But judging from all the people in this forum complaining about American Standard's Champion toilets, I guess a lot of companies don't really care about making good products! Thanks again guys for taking time...

12-09-2005, 12:20 AM
Well, I just completed installing this shower kit and the bottom line is I would not buy another corner shower made of polystyrene. I don't think this material is tough enough to last very long. Next time I intend to buy a one piece fiberglass kit that requires walls on 3 sides. I am guessing that this kind of construction will be much sturdier and will last much longer.

Anyway, after buying this kit from HD and wondering what to do about a base that I considered to be improperly supported I visited a Loews by chance and saw this very same shower in a demo setup. I stepped into the shower and there was about a 1/4" flex of the base!! ( I am guessing that this demo has been up for about a year). At this point I knew that my instinct was correct and that I had to do something to properly support the shower base. I proceeded to rip out the Styrofoam supporting the flat floor and then glued 5/8" plywood to the underside of the base. I then glued about 12 - 2" x 2" posts (the heights varied from 1 1/8" to 5/8" ) under the plywood to make up for the space vacated by the Styrofoam. The floor feels good under my weight but truthfully I don't think it will last more than 5 yrs. Like I said, I don't think these plastics make sense when it comes to showers unless it is for a situation where it will have only very light use!!

12-24-2005, 07:33 PM
Ok, well I went to the Schluter website but I did not get too much from the visit. Anyway, I am not an expert by any means, but to me, a shower pan is a waterproof containment but does not necessarily provide structural strength. If a styrofoam pan is under a tiled shower base, I don't have a problem with that because the tiled base would not flex and cause the styrofoam to flex and weaken. In my case however, the flexible polystyrene shower base is supported by styrofoam (on an earlier post, I said it was denser than the packaging kind of styrofoam, but in fact it is appears to be the same thing) and there is no way that it will not compress over time. Thanks for you input however.

12-28-2005, 07:26 AM
sounds like you looked into this inferior pan thoroughly. i can't believed you installed it after what you described. i would be upset if i remodeled my bath and only expected to get 5 years out of it! a correctly installed bathroom should last 20 years + with quality fixtures. so in 15 years you will have remodeled your shower 3 times?
best bets are an acrylic pan set in mud or custom made pan done correctly.