You've got to have 4" in height difference between the drain and the edge of the shower. The slope of the shower can be between 1/4"-1/2" per foot. Using a trench drain at the opposide side from the shower entrance seems to work best for many curbless showers as opposed to the giant bowl in the middle where everything slopes down to it. It gives you the ability to have less slant because you've got more distance from the shower entrance.

Yes, it's "expensive". Depends on the structure of your house if it's merely "expensive" vs. "exorbitant" and it depends on your economic scale as to where those terms begin for you. As to whether or not it's "worth" it to you, for most people, a nice large shower IS worth the expenditure. A shower that has the blocking in the wall so that the grab bars can be attached at any time IS worth it. Curbless---eh, maybe.

As far as a shower that large, think twice unless you are also installing supplemental heat like a heat lamp. Even then, that's a lot of open space for your steam to heat up on a cold morning. I'm shivering just thinking about it!

Hollysprings,

Thanks for the explanation. We may get an estimate for curb less but it sounds like its not an absolutely must have. DH's big shower is still under negotiation...... And we have decided to do radiant heat in both the bath and shower floors in addition to the baseboard heat.

Thanks!

I'm not certain where hollysprings' 4" reference comes from, it's typically 2" when referencing IRC code. That's a minimum of 2" from the top of the drain to the top of the curb. In a curbless shower, the beginning of the slope at the shower entry would be the "top of the curb."

Over the course of the 8' length of the shower, using 1/4" slope per foot would give you the needed 2" vertical.

FWIW, my master shower is about 8' by 5'. No door. NOT curbless. It's not cold. I do have RFH throughout my house though.

To help with the elevations changes, you can "drop the framing" in the shower as you wrote about, or you can build the bathroom floor up vertically outside the shower. Both have costs and issues, especially in a remodel. Dropping the framing in the shower is much easier when working with new construction. If you have easy access through a drywalled ceiling below, it can be done. But it can be involved.

Probably the more prudent thing to do is if your shower is indeed 8' long, you can do as hollysprings wrote and have the drain at the far end of the shower, away from the entry. But don't make it a true curbless.

If you went with a standard vertical curb at the entry and used a topical membrane, your vertical curb at the entry would only have to be a couple of inches tall.

If you wanted it to be a roll-in shower, you could easily turn that 2" vertical curb into a "roll-over ramp" at the shower entry, sort of like a speed bump. A small rise up, then the long slope down in the shower terminating at the linear drain.

Thanks Mongoct! I think I we will have curb but will look into a linear drain on the far wall.

They will have to lower the flooring enough not only for the 2" slope, but also for the pan. Probably going to be right at 4" for all that.

A few weeks ago we had a consult with an apparently high end kitchen/bath designer. He said it would cost 5000-7000 extra to do this. We are on a concrete slab so it is probably a lot more work/expense that without a slab.

Thanks for all the feedback. As cool as curbless sounds... I think we will probably end up with a curb. I will research getting the drain (maybe linear) of the far wall as Mongo mentioned to minimize the the height of the curb. The wish list for this bathroom is, at this point, a blank slate. The budget however, is firmly rooted in reality. I think this is one of those things that is on the "nice to have" as opposed to "have to have" list. I've seen picture of a few with curbs done with marble slabs as opposed to small tiles that look pretty nice. And stylistically, it works as our house is a pretty traditional New England colonial.

BUT I am now on a hunt to find out about Elfaba's Moen digital shower valve....... Thanks, it's sounds like a great idea!

Regarding Moen digital shower - it is WONDERFUL but...
we had to learn the hard way that it needs a battery backup so that if the electricity goes off, the digital shower won't turn off until it is manually reset.

Isn't the end of the world but we have to "reset" the data line for the valve by going to the access panel whenever there is a power outage (like when the guys work on the house).
Isn't a really big problem and we haven't got the power backup drive yet (that will be mounted on a small shelf in the closet adjacent to the valve) but... my main advice is make sure the access panel for your Moen Idigital valve is readily ACCESSIBLE! Don't put the access panel in the attic or somewhere that may be tedious to get to.
Part of our problem is that we are having a lot of work done on house so more than our fair share of outages.

My NEXT bit of advice, make sure you have a 2nd bathroom with traditional shower valves so in case there is a power outage, you can still take a shower.

The biggest hassle has been the learning curve, i.e. before we realized what the problem was. We almost had the access panel put in the attic. THANK GOODNESS we didn't do that.

I called Moen and the customer service there recommended the power back up.

Also, FYI - there is a video on youtube.com that shows a standard installation. My contractor watched that and didn't charge me anything extra. Though someone else here on gardenweb said their contractor charged them extra because of the complexity - funny but to me, it is actually simpler than regular shower valves and definitely a cleaner look. Oh well -