I am having our basement development worked by a contractor. He installed the 2 PC. Shower stall early in the development stage. He opened the concrete to install the pipes then put the 2 PC (base and wall) but it was left opened underneath. They are now doing the finishing and still they have not covered the underneath of the shower base with concrete. I am not sure what needs to be done with this and I want to get other's advice. Shouldn't this be finished with concrete? It is all dirt and stone underneath the shower base. Please advice.

There should be a mortar bed underneath it. Go to the website for the manufacturer of the shower stall and see what they recommend so the warranty isn't voided.
Tips for installing a prefabricated shower stall - by Curtis Carper - Helium (http://www.helium.com/items/508744-tips-for-installing-a-prefabricated-shower-stall)

I agree, setting anything on just soil sounds like a big problem later. Have them pour 4" of concrete beneath the base.

Roger

Roger gave you an understatement, this would be a huge problem down the road. I am starting to wonder about your installer, he should have known better.

Thank you all for your advice. The contractor poured concrete underneath but they can only do as much, this is what they say. The back of my bathroom is unfinished the unfinished mechanical room so I was still able to take some pictures. I have inserted pictures for you to see. Tell me what you think. Is this enough?

11032008304 on Flickr - Photo Sharing! (http://www.flickr.com/photos/32399443@N06/3026215475/)

11032008299 on Flickr - Photo Sharing! (http://www.flickr.com/photos/32399443@N06/3027054946/)

The dark color below is the concrete they poured. It is not as high as the original concrete.

Not good enough and the contractor should know this. There must be copntact between the bottom side of the pan and the cement floor. At this point I would use insualtion foam from a can but specila stuff used around windows and dorr frames. The reguilar stuff expands to mucjh and could l;ift the floor.

No waterproof membrane? No lead pan?. where are you located?

Vore... this shower base does not require a membrane or lead pan. It is a 2 PC. Pre-fab. Shower unit.

Xtalgem... As Ballenger said, this is done wrong and you can figure on issues down the road if this is not remidied now (floor will flex and seal between drain and shower floor will break down over time). I would have the installer or you find a local retailer that sells STRUCTOLITE perlited gypsum (see picture of product).

Take the structolite and mix it to a thin slurry... pour this slurry under the showewr base until it overflows the underneath. Then mix a little more structolite... normal thickness (as directed on bag) and build up around the base walls about 3-6 inch off the floor.

Let that dry 24 hours and this will ALL be fixed...

Let us know if need more info. Here.

MARK

Vore....this shower base does not require a membrane or lead pan. It is a 2 pc. pre-fab. shower unit.

Xtalgem...As Ballenger said, this is done wrong and you can figure on issues down the road if this is not remidied now (floor will flex and seal between drain and shower floor will break down over time). I would have the installer or you find a local retailer that sells STRUCTOLITE perlited gypsum (see picture of product).

Take the structolite and mix it to a thin slurry....pour this slurry under the showewr base until it overflows the underneath. Then mix a little more structolite...normal thickness (as directed on bag) and build up around the base walls about 3-6 inch off the floor.

Let that dry 24 hours and this will ALL be fixed...

Let us know if need more info. here.

MARK

I get it. In NYC we would still be required to line the entire floor with a waterproof membrane (tub to shower conversions). Actually each building has it's own guidelines but we do it anyway.

This idea that a membrane is need with this fiberglass shower is totally wrong. A membrane is not needed under this kind of pan. Do we install a membrane under a fiber glass tub, no way.

This idea that a membrane is need with this fiberglass shower is totally wrong. A membrane is not needed under this kind of pan. Do we install a membrane under a fiber glass tub, no way.

ballengerb1... chill out. Different areas of the country have local state and or city codes. From a New York State (of mind) we are required (dependent on the circumstances and the building managements involved) to install a membrane. It's not a requirement of "everywhere" in the country.

Some managing agencies in our fair city require us to replace all the branch lines when we remodel a bathroom or kitchen... again... different rules for different locations. That's why I asked where the poster lived.

Please quote the code that says you need a membrane under a fiber glass tub, shower. Even local codes, funky as they might be, generally follow International Codes. I think many of us would be interested to read what city, county or state has this code.

Please quote the code that says you need a membrane under a fiber glass tub, shower. Even local codes, funky as they might be, generally follow International Codes. I think many of us would be interested to read what city, county or state has this code.

Yeah... I'll look that right up for you... please re-read my posts.

Vore, you might be misreading me. It is common for us Experts to quote code so when I hear of a code not known to me I need to expand my knowledge. I do not want to quote something I can't back up later if someone questions me. If you say its code it is not uncommon or rude for us to ask you for a code quote. I am not being arguementive, just need solid facts for the future. Many of the experts have asked this same question on other threads.