# Minumum thickness for deck mud



## calypso (Dec 8, 2004)

I am going to build a shower floor that slopes downward from the finished bathroom floor height so there won't be anything to step over to get into the shower area. Is there a reason the final deck mud over the liner is around 2 1/2 inches thick? Wouldn't an inch of deck mud along with half an inch of slate tile and thinset over the liner be really strong and water tight?


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## JJC (Nov 5, 2005)

Yep, it is for stability of the mud.


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## calypso (Dec 8, 2004)

OK, thanks JJC. I will make the deck mud 2 and 1/2 inches thick.


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## HJ1 (Sep 28, 2006)

2 1/2" is not necessary and overkill I think. 1 1/2" thick is what I do for a final bed.


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## JJC (Nov 5, 2005)

calypso,
The height of the shower floor will depend on the distance between the drain and the farthest point. The pre-slope pitch is run at 1/4" per foot minimum. then the liner. Next the mud bed is packed and shaped over the liner with a minimum 1-1/2" thickness at the perimeter. As I said in the beginning, the distance between the drain and the longest run will determine the perimeter thickness. One needs to plan carefully and correctly before lowering the joists.
Jim


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## calypso (Dec 8, 2004)

I was thinking about that today JJC. If the farthest run is 5' the slope rise would be 1 1/4 inches. By the time I add the slope mud, liner, deck mud and slate tile I will have to lower the floor joists in the shower area around 3 1/2 inches (with a deck mud of 1 1/2 inches like HJ1 suggested). I guess I have some creative floor framing to do.


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## JJC (Nov 5, 2005)

I say you are correct! Is the whole bath going to be treated as a wet room? I mean will it have a membrane throughout? Also when you cross over the joint of mud to regular flooring, don't forget to make it a soft joint to compensate for future cracking in at that joint.


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## calypso (Dec 8, 2004)

The only place there will be a liner will be in the shower area. It will have a pair of those cool glass doors (forgot the name). I hadn't thought about the transition where the deck mud meets the rest of the tile floor. Thanks for the tip about a line of flexable grout. I will post some pictures when I get it done.


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## HJ1 (Sep 28, 2006)

Any reason why you cant do a kerdi shower? You save yourself 1 1/2" in floor height. Kerdi goes right over the preslope with no need for a mud bed over it. Tile goes right over the kerdi. It requires a special drain but it sounds like you havent gotten that far yet.

Check out the schluter website for info on kerdi showers.

http://www.schluter.com/8_1_kerdi.aspx


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## calypso (Dec 8, 2004)

Thanks for the link HJ1. I think I will make a sloped mortar bed and then use the kerdi system.


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