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yohan 06-05-2007 12:11 AM

Fiberglass Shower Base Install Q's
Hey everybody, this is my first post.

After countless hours of googling etc. I am finally asking for specific details to my project.

I'm building a bathroom in my basement, the plubming already is roughed in and the drain etc. is all allocated as well as the water.

I have framed in for a shower base to be installed, the walls will be tiled. I have greenboard drywall over majority of the walls around the shower already and only the bottom is cut out for install of the base.

I plan to put cement backberboard on the bottom 24" or so of the shower. This is where my question is.

The shower base has a lip on it, do I need to put the cementboard over this lip or can I put it down to the top of the lip and tile lower so its flush with the base? ... this attached pic should help explain:

I believe that I need to put screws to hold the base to the frame .. but am not sure if I need to put any mortor etc. on the floor.

I greatly appreciate all help on the specifics of this install!

send_it_all 06-05-2007 12:42 AM

A few issues here. You should have NO GREENBOARD behind your tile. You should have the cemetious backer board over a layer of vapor barrier that is stapled to the studs. Start the vapor barrier at the bottom letting it overhang the flange on the fiberglass pan...Which, by the way, should be installed on a mortar bed to eliminate flex. (I use fixall, some use joint compound. mix in a bucket and pour it on the floor JUST before setting the pan for the final time...fixall dries very fast so be quick about it.) wrap the vapor barrier horizontaly around the perimiter of your shower. Since it is only 3' wide you will need a few layers. Overlap the next layer over the previous by about 6-8" and repeat until you get above your tile line. Then install the cement board. It can sit on top of the flange. Follow mfrs insructions on cutting, screw spacing, and board spacing. You will need to tape the seams using alkalai resistant cement board mesh tape.(not drywall tape). Some people say to tape the seams as you tile so you wont have humps to tile over...sounds good to me. Hope this gets you pointed in the right direction. By the way, there is no shame in farming this out. The results from a prefessional will not only look better, but potentially save you thousands in damage from an improper installation....such as greenboard or no vapor barrier. Be careful.

yohan 06-05-2007 12:48 AM

this is great advice, i'll for sure put some vapor barrier in against the studs.

is it ok in the picture to put the concrete board down to the rim and let the tile overhang the flange? .. do I need to put something along the flange behind the tile or will it be ok? i've seen mixed diagrams on different sites..

send_it_all 06-05-2007 12:56 AM my opinion it is ok...I think I mentioned that in my post, but I like to fill the void left behing the bottom tiles with thinset as I tile just for a little support.

yohan 06-05-2007 01:04 AM

Thanks very much for the extra advice and confirming my assumption on the install! I will also fill the gap between the flange and tile with thinset.

since this is going straight on to the concrete floor, any other advice for leveling the shower base on the mortar/joint compound?

send_it_all 06-05-2007 01:16 AM

Since I have only installed one fiberglass pan (on level concrete) the only advice I can give about leveling is to have a level handy when setting into the mortar bed and check it in all directions as you press it down. When you have it set level, leave it alone until the mortar dries then go back and fill any gaps under the dam (shower entrance) with some plastic (not wood) shims and use construction adhesive to keep them there permanently..this will help eliminate flex as you step in and out of the shower. Floor tile will cover the gaps. (Im assuming you are tiling the floor) The same principal applies to a vanity cabinet. I like to shim it level then use tile to cover gap.

yohan 06-05-2007 01:27 AM

How thick should I lay the mortar?

send_it_all 06-05-2007 01:41 AM

Turn your pan upside down on a carpeted or protective surface and lay a level or straight edge across the surfaces that rest on the floor, then measure the gap between the bottom of the pan floor and the level. I would lay the mortar about 3/4 of an inch thicker than that measurement. Then when you set it, press it down and let the mortar squeeze toward the cavity at the edges. Try to imagine the amount it would take to create a solid bed of mortar that covers the entire pan floor. Its ok to use a little too much because it will just wad up in the cavity at the edge. Hopefully someone with more experience with fiberglass pans will chime in....I've reached the edge of my expertise in this matter, I'm starting to delve into If we focus on walls, I might have more to add.

dinah 01-07-2011 03:46 PM

shower pan installation
My boyfriend is putting my shower pan in for me and he just put the mortar down and put the pan in. He then put screws into the pan at the top to hold it in place. It's done, but was this a good idea?:whistling2:

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