# Installing Trench Drains in Curbless Showers



## mark handler (Jan 8, 2019)

Interesting paper on Installing Trench Drains in Curbless Showers



https://projects.ncsu.edu/ncsu/design/cud/pubs_p/docs/trench_drain.pdf


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## onemorevillegas (Aug 17, 2020)

great, thank you.


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## e hilton (Aug 17, 2020)

Nice detail ... except ... on page 2, the wood framing detail, they conveniently show the floor joists under the shower to be about 1” shorter (shallower?) that the rest of the floor, but fail to call that out in a note.  Easy enough to do in new construction, could be tricky in a remodel.


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## onemorevillegas (Aug 17, 2020)

e hilton said:


> Nice detail ... except ... on page 2, the wood framing detail, they conveniently show the floor joists under the shower to be about 1” shorter (shallower?) that the rest of the floor, but fail to call that out in a note.  Easy enough to do in new construction, could be tricky in a remodel.



I recently replaced floor joists for new as the previous were all sandwiched together.
After realizing we needed to lower the shower, we notched the 2x8s out with the sawzall.
We then sandwiched additional 2x4 wood to provide some extra strength.


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## e hilton (Aug 18, 2020)

A sistered 2x4 doesn’t add any strength to a hacked 2x8.  It’s too shallow, doesn’t have any reasonable span distance by itself.  Better solution would be to add a new full length 2x8 dropped an inch or two, with appropriate hangers at each end.   With engineers approval, you could use simpson 2x10 joist hangers with 2x8 lumber to get a lowered floor.


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## Yikes (Aug 18, 2020)

Question:  there is no fastening of the plywood to the metal angles - - is it necessary?  Or does the plywood existing solely as a formwork that gets pinned into place by the weight of the mortar above?


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## mark handler (Aug 19, 2020)

Yikes said:


> Question:  there is no fastening of the plywood to the metal angles - - is it necessary?  Or does the plywood existing solely as a formwork that gets pinned into place by the weight of the mortar above?
> 
> View attachment 6869


Yes it looks that way.


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## conarb (Aug 19, 2020)

I don't come by here anymore but I had to comment, I haven't had an architect detail a curbless shower drain like that in 40 years, they all specify drains like *Acco*, I have had problemss with the weep holes being inadequate and people have to remove the grates to clean out "hair baskets" which they never do.


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## steveray (Aug 20, 2020)

conarb said:


> I don't come by here anymore but I had to comment, I haven't had an architect detail a curbless shower drain like that in 40 years, they all specify drains like *Acco*, I have had problemss with the weep holes being inadequate and people have to remove the grates to clean out "hair baskets" which they never do.


Good to see you CA! Take Care!


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## ADAguy (Aug 27, 2020)

Smoky up your way eh! Don't forget to mask.


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## Keystone (Sep 22, 2020)

Curb less showers, fantastic concept, seamless transition & readily accessible. What point do you stop the floor system protection? If it’s a renovation or new construction installation with wood floor system, does the floor system stop at what would be the perimeter of the shower or does the shower extend through the entire bathroom up to the entry door?   We know the sloping would stop within the determined areas of the shower but what about the remaining floor surface of the bathroom?


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## Robert (Sep 22, 2020)

Like Keystone, I'm curious too in your experiences with slot drains and the extent of the membrane. Years ago when these were just coming out, one local jurisdiction made us membrane the entire bathroom, up the perimeter walls and required a wall hung toilet (no hole in the floor for water seepage). Now I don't know what they are building and accepting in the field.....I think less strict now. Even if you took the membrane all the way out to the bathroom door, you would have to fold it back on itself to form a dam since no curb. Here is a worse case scenario: The lowest trap on the bottom floor will be a shower (or tub). If there is an obstruction way downstream, and the washing machine or dishwasher is dumping water into the line, the first trap to overflow will be that shower, and without a curb you wouldn't know it until the whole room is flooded. That's the only thing I can think of as to why the entire room needs to be waterproofed.


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## Keystone (Sep 22, 2020)

“Culwell Flange”.  This is a flange designed for for use with a floor membrane.


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