# installing shower pan on a concrete floor



## Termite

OK Steve,

Throw out the poly sheeting. You need rubberized shower membrane material. Poly won't cut the mustard.

On the basement slab, you need a bond break. I'd use either 15# building felt of even Ditra. You don't want the shower's base bonded to the slab. Trust me, it isn't going anywhere.

Then, you need a pre-pan that is sloped to the drain. Your water membrane will sit on this. 

Let's talk "mud." You DO NOT USE CONCRETE in a conventional sense. You must use a mix of three parts clean dry sand to one part portland. This mix is available at tile suppliers. Per 50# sack, you mix in 1/2 gallon of water...No more. The lack of water makes it super strong. It will be the consistency of wet sand, but not "plastic" like concrete. The mud is packed into place using a trowel or float. Pack hard. It should be no less than an inch thick at the thinnest part, give or take a little. Sprinkle a little water on the surface once you've got it all shaped and looking good. I'd also recommend covering it with something (like the poly) to help it cure without too much evaporation. Once dry, remove the covering. 

Once the pre-pan is cured for a day or more, apply the membrane. The membrane goes at least several inches up the surrounding walls and also gets incorporated into the curb. Use no fasteners except at the very top...Roofing nails work well, nailed into the studs. You'll have to fold and overlap at corners, and they also make a solvent weld cement to make it easier. The membrane must be incorporated into the drain. They make special drains that clamp the membrane, available at tile suppliers. Also, your membrane should go under your cement backer board on the walls. Do not fasten the cement backerboard to the studs through the membrane. You need a few inches to hang down with no nails or screws. If you penetrate the membrane too low, it'll leak.

Now set your drain.

Now you're ready to place your final mud base. It is done the same way as the pre-pan, with the same mix, packed in place. I did mine about 3" thick, tapered to about 1-1/2" at the drain. You must have at least 1/4" per foot of slope. In the same "pour" as the final base, you should form your curb and place it as well. Same material. I always incorporate some strips of metal lath for reinforcement. That's overkill, but it makes me happy. Be sure to slope the curb toward the drain if you're using a swinging shower door. If glass/track are being sealed to the curb, the slope is less critical. 

You'll need some basic concrete tools to do the pre-pan and base. A 12" wood or magnesium float is perfect. I'd also suggest a small trowel, like a margin trowel. These are helpful for packing and smoothing the base as well as the curb.

I'd recommend going to a good tile supplier to get your membrane, base mud, and thinset. Their quality is typically better than what you can get at box stores. DO NOT USE PRE-MIXED THINSET. And for God's sake do not use mastic. Use dry mix modified thinset. 

Just two more suggestions...
Be sure that you waterproof your walls' backerboard. Cement board, grout, and tile are not waterproof. RedGuard is a paint-on product that works great. It goes on the board, and once dry, you can tile. This is an incredibly important step.

Also, don't forget to mud and tape the cement backerboard's seams and corners. Use mesh fiberglass tape made specifically for backerboard. Use thinset to fill the joint, bed the tape, and cover the tape. Just like drywalling, only looks don't matter.

Hope all this helps.


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## Termite

By the way, I moved this thread from the plumbing forum here to remodeling. :yes:


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## sv9779

Wow, that's great info. Thanks so much for taking the time to help. That really clears up a lot of questions. 

Thanks again, Steve


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## sv9779

By the way, love the picture of your Chocolate Lab! We also have one.

Steve


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## Termite

Yeah, that's Moose, my project assistant. He's a good dude.

Feel free to post any questions that you have as you get this going. Most tile shops can really help you with some good advice on doing this, and many have displays that show how it all goes together as well.


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## sv9779

Moose... I love it!! I call ours Moose-Dog. Though her name is Montana Mae. "tana". But she's a big 90 pound moose. 

Thanks again for the help. I really appriciate it.

Steve


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## Termite

I see your 90 pounds and raise you 33. Moose is 123 pounds. 90's huge for a female though! Moose needs to lose 10 of them to get back to his duck-retrieving weight.


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## sv9779

They do love thier groceries! 123 is a big boy! Tana was at 108, but we've had her on a diet. She never really looked fat. But she's having hip problems, so the vet wanted her down a bit.

Off to work on the shower!


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## jon#391u

*Shower Drain extension*

I'm getting ready to follow the above instructions this weekend but I have a question before I get started. 

How do you extend a cast iron drainpipe? The pipe sits flush with the surrounding cement but I still have to level and float the floor (not to mention add tile). By the time I get done the drain will sit 2 to 3 inches lower than the surrounding cement. The drainpipe has no threads or places to bolt to.


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## angus242




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## jon#391u

How do I attach that to the cast iron or do I even need to attach it?


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## angus242

Hmm, I don't remember the specifics as my plumber actually did the work. I was just being nosy. 
I believe the black ring you see is a rubber gasket. In my case, it was a red o-ring/gasket. You grease the gasket and it's a very tight fit. Just slip fit and then screw the flange to the floor. :thumbup:


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## jon#391u

Thanks, I will give it a shot. By the way your bathroom looks good. It's kind of what I'm trying to do.


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## sv9779

angus242 said:


>


 

Looks like a toilet flange. not the 3 piece shower flange.


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## sv9779

Just a thanks for all the help on the show pan install. Got the pan in and inspected. Spent serveral weekends tiling it and had our first guests us it over the holiday.

Happy New Year


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## sv9779

Here is a utube video that shows the shower drain 

http://www.youtube.com/watch?v=xQQjcPdGs90


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## cvanden8712

thekctermite said:


> OK Steve,
> 
> Throw out the poly sheeting. You need rubberized shower membrane material. Poly won't cut the mustard.
> 
> *On the basement slab, you need a bond break. I'd use either 15# building felt of even Ditra. You don't want the shower's base bonded to the slab. Trust me, it isn't going anywhere.*
> 
> Then, you need a pre-pan that is sloped to the drain. Your water membrane will sit on this.
> 
> Let's talk "mud." You DO NOT USE CONCRETE in a conventional sense. You must use a mix of three parts clean dry sand to one part portland. This mix is available at tile suppliers. Per 50# sack, you mix in 1/2 gallon of water...No more. The lack of water makes it super strong. It will be the consistency of wet sand, but not "plastic" like concrete. The mud is packed into place using a trowel or float. Pack hard. It should be no less than an inch thick at the thinnest part, give or take a little. Sprinkle a little water on the surface once you've got it all shaped and looking good. I'd also recommend covering it with something (like the poly) to help it cure without too much evaporation. Once dry, remove the covering.
> 
> Once the pre-pan is cured for a day or more, apply the membrane. The membrane goes at least several inches up the surrounding walls and also gets incorporated into the curb. Use no fasteners except at the very top...Roofing nails work well, nailed into the studs. You'll have to fold and overlap at corners, and they also make a solvent weld cement to make it easier. The membrane must be incorporated into the drain. They make special drains that clamp the membrane, available at tile suppliers. Also, your membrane should go under your cement backer board on the walls. Do not fasten the cement backerboard to the studs through the membrane. You need a few inches to hang down with no nails or screws. If you penetrate the membrane too low, it'll leak.
> 
> Now set your drain.
> 
> Now you're ready to place your final mud base. It is done the same way as the pre-pan, with the same mix, packed in place. I did mine about 3" thick, tapered to about 1-1/2" at the drain. You must have at least 1/4" per foot of slope. In the same "pour" as the final base, you should form your curb and place it as well. Same material. I always incorporate some strips of metal lath for reinforcement. That's overkill, but it makes me happy. Be sure to slope the curb toward the drain if you're using a swinging shower door. If glass/track are being sealed to the curb, the slope is less critical.
> 
> You'll need some basic concrete tools to do the pre-pan and base. A 12" wood or magnesium float is perfect. I'd also suggest a small trowel, like a margin trowel. These are helpful for packing and smoothing the base as well as the curb.
> 
> I'd recommend going to a good tile supplier to get your membrane, base mud, and thinset. Their quality is typically better than what you can get at box stores. DO NOT USE PRE-MIXED THINSET. And for God's sake do not use mastic. Use dry mix modified thinset.
> 
> Just two more suggestions...
> Be sure that you waterproof your walls' backerboard. Cement board, grout, and tile are not waterproof. RedGuard is a paint-on product that works great. It goes on the board, and once dry, you can tile. This is an incredibly important step.
> 
> Also, don't forget to mud and tape the cement backerboard's seams and corners. Use mesh fiberglass tape made specifically for backerboard. Use thinset to fill the joint, bed the tape, and cover the tape. Just like drywalling, only looks don't matter.
> 
> Hope all this helps.


Hi I'm Chris, I'm getting ready to remodel my bathroom in my parents house. The bathroom is on the down stairs so there is a concrete slab. I've done tile work but never build a shower pan. Current shower pan is fiberglass which I plan to remove. I was searching and found this thread on how to build a shower pan on a concrete slab.

The builders felt how are you attaching that to the concrete or is just floating? Then I build the first layer of the pan right on top of the felt using concrete floor mix? Then membrain then the final layer of the mud. Once dry can start laying tile? I'm not one to read and understand, more of a hands on type of person.


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## sv9779

Hi Chris, My gosh, I forgot how long ago I put that shower in! 2008. Anyway, I really can't remember all the steps. Which is problematic because I have to do another one soon. I did get something called a Quick Pitch shower kit. It slops the drain for you. I still have one in the shop for the next shower. Do a Google search for Quick Pitch Shower and you'll see it. There are also lots of YouTube videos that show all the steps you need to do. I also do better when I can see it done. Now you can also get Kirdi water proof membrains and floor kits. A Google search for Kirdi Shower will get those results.
Good Luck
Steve


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## cvanden8712

Thanks Steve, Ill look into those.

My biggest worry right now is where I start. I know roughly how big I want the curb for the entry of the shower. Just trying to figure out what goes on the floor first.


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