Cracked Shower Pan Repair and Rebuild

[Icehouse]

I just completed the repair of my cracked shower pan. The cause: styrofoam base supporting plastic/fiberglass shower pan. Over time, human weight crushes styrofoam causing compression and then shower pan flexes and cracks. I have photos here: http://s246.photobucket.com/albums/g...Pan%20Rebuild/
The challenge with this fix is that the shower pan has a slope to allow water to run toward the drain hole. The back corner - farthest from the drain - requires a foundation depth of 1 5/8 inches while near the drain the foundation depth is 1 1/4 inches. This required some creativity in getting a sloping foundation to properly support the shower pan while creating a strong, non-flexible foundation so the pan will not flex and crack again.

My solution: a two piece foundation. I used 1 X 4 inch pressure treated board to create a non-solid yet firm radial foundation with shims to create the necessary slope. Accurate measuring of depth is critical. Part two is a solid 7/16 thick OSB board cut into the shape of the original styrofoam. I did extend the size of the OSB foundation slightly to provide more support for the shower pan. I screwed each of the radial boards down with deck screws and then used the same screws to attach the OSB foundation board to the radials. The 7/16 thick board is sufficiently strong not to flex or bend in the small gaps of the radials. I then decided to add a single sheet of fiberglass matt sheeting between the OSB and the shower pan. This serves no real purpose other than it makes the sound of standing in the shower less echo-ey. I just taped this sheet to the bottom of the shower pan prior to re-installing.

I have some dimensions and drawings to add. I will also add some photos of re-installing the glass enclosure and framing.

[RRman]

Great Job, thanks for the report/details!

[snfexpress]

Do you think there is something we could do to prevent the cracking based on what you had to go through?

[Icehouse]

You know, as long as styrofoam is continued to be used as a base, over time it will always crush in some form or fashion. If there was some way to get under the pan, cut an opening behind the shower, and slide a thin (1/16 - 1/4in) board between the bottom of the pan and the top of the styrofoam, that might help to distribute the weight some. HOwever, the styrofoam is taped to the pan and then just stuck from time. What I find interesting, is when looking for replacement pans, they appear to come with wood supports.

[snfexpress]

What do you think about the expanding foam insulation, the stuff that expands the least?

[Icehouse]

In some situations, that might work. I did try that before this repair. What I did not know was the solid styrofoam between the pan and the floor. My expanding foam looked and felt like it would do the job. What it really did was expand under the styrofoam and ooz to the side where it just filled in around the side of the pan. The styrofoam compresses on top - directly beneath the pan and your feet. When installing the expanda foam, I had to enter from underneath through the floor and just did not get high enough to fill the compression and it just ran around the bottom - never touching the compression. If you could come in from the side between the pan and the styrofoam, I bet it might work. I would put a really really heavy weight in the shower pan to prevent buckling and bumping.

[snfexpress]

Good point about side installation and putting weight on pan. Thanks!

[Trailer Trash 2]

hay Mike why cant you add some straws to the expanding foam nozel and get it all the way in the back of the pan and pull it out as you put the foam in between the pan and sub floor.

[snfexpress]

Hmm...

[scductman]

Bernie mine has a low spot that has started at the left of the drain. so when we get home in november I am going to take mine out and fix it like you did. a question how did you get the base out without removing the shower walls or atleast it looks that way. I spray foamed mine 3 yrs ago around the drain to keep it from flexing but it started to shag again in the last few months and I am afraid it will crack like yours.
Bobby

[Icehouse]

It sounds like your sag is in the same place mine started. Truthfully, it would have been easier to remove the shower walls however, I was able to wiggle out the shower pan without removing them. Getting them back in was the challenge. They are actually quite flexible - more so than I was comfortable with - but it did work. The pan only goes behind the shower walls about 1/2 to 3/4 inch. On this lip, there were 5 screws that held the shower pan in place behind the bottom of the shower walls. My shower walls did pull away from the the wall and pulled out the bottom wall secure screws. However, when putting it all back together, my shower door glass walls held the plastic shower walls in place. I also added some caulking type adhesive to the edges of the shower walls to help secure them. When put back together, everything is holding nicely. Let me know if you have questions as you proceed.
Bernie

[scductman]

Thanks Bernie Thats what I thought but was not sure. the bottom of my walls are not tite to the wall and the shower glass was leaking at the base a couple of months ago so I caulked around it at the bottom but I want to take it all out and fix it like it should be.
Bobby