Thread: Shower pan depth

Is there a standard or minimum depth for tiled shower pans from the curb to the base. I figured, after 3 2x4's it should be at least 3" or so after mud.

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Have you not heard of a "curbless" shower area? Or considered a shower area with multiple showerheads, and supply controls?

You could effectively "pan" the entire room or uncompartmentialized area, utilize a trough drain or other, and tile walls, panned floor and use sanitary base, for example, or place in center of area, ring curtain, shower from overhead, and drain, sanitary base tile perimeter of room and skip tiling the walls all together, as long as youve trapped, vented and servicable dwv.

Sufficient slope to and DFU of the drain(s) to affect complete drainage and contain within the area, while in full "use" and drain completely immediately thereafter area is in-use.

If you are referring to an approval standards for pre-manufactured pans, they vary upon application details, size, area; location, size and type of drain(s); number, type, flow, of shower "heads", and other sources of water/steam; design, and application; requiring calculations. Specific products and applications have their own specifications and limitations.

I suspect your question has more to do with guidelines/recommendations from shower doors and other shower compartmentalizing assemblies/installations/designs; or possibly protection of other systems adjacent or below, or the building itself, etc; or perhaps how do determine the minimum required slope and drain and venting requirements for a particular shower area containing x fixtures.

There is a rapidly growing trend to install multiple showerheads in single user shower stalls, in attempts to subvert the Federal requirements of 2.5 GPM (9.5 LPM) maximum flow rate for showerheads. There are current efforts to develop plumbing code regulations to close up this loophole. Water conservation advocates are encouraged to support local, state and national efforts to restrict showerhead installations to standardized health codes of no more than one showerhead per 1296 square inches (8281 square centimeters) of shower stall floor area, and require showerheads to be at least 36 inches apart (.91 m). This proposed requirement would not allow a second showerhead installed unless the shower stall was designed for two persons (minimum of 2592 square inches of floor area).

For some more information on showers and non-compliant showerheads and showering systems access, I suggest these Alliance for Water Effiency web resources:
Non-Compliant Showerheads Introduction </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=2000>
American Society of Sanitary Engineering (2010) Scald Hazards Associated with Low-Flow Showerheads: A White Paper Press Release </uploadedFiles/Resource_Center/Library/residential/showers/ASSE-ScaldHazards-PR-October-2010.pdf>
American Society of Sanitary Engineering (2010) Scald Hazards Associated with Low-Flow Showerheads: A White Paper </uploadedFiles/Resource_Center/Library/residential/showers/ASSE-Scald-Hazards-Associated-with-Low-Flow-Showerheads-White-Paper-2010.pdf>
Koeller, J (2008) Danger in the Shower - 2008 Forum Looks at Hot Water </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=2710>
Biermayer, P. (2006) Trends in Shower Design and Their Effect on Energy and Water Use </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=1828>
Biermayer, P. (2006) Potential Water and Energy Savings from Showerheads </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=1826>
Koeller, J. (2005) Selected Quotes on Market Trends Showerheads and Shower Systems </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=1830>
Biermayer, P. (2005) Showerheads - Current Market Trends and Potential Loss of Savings </WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=1832>

HG brings up a very good scenario that is often overlooked Stateside. In Europe, possibly other places I don't know, it is common for the bathroom to be its own 'pan'. Bathrooms often times have a floor drain, the entire floor is a pan. This is especially true if the bathroom has a walk-in shower stall. The floor is sloped appropriately, the shower area doesn't have a curb and excess water is just squeegeed to the drain.
I'd love to see bathroom floor drains and the bathroom pan concept become more of a standard here than an oddity. Don't see it happening though.

Markus,

This is becoming more and more popular, especially with the aging population, and with "accessiblity" and "assistance" needs of an ever-increasing percentage of our population.

The how-to's aren't new - we've been doing same in non-private and multi-user shower/bathroom areas, nursing homes, hospitals, etc. for decades. Pre-formed or pre-manufactured "shower pans" are the "something new" and DIY'ing all trades work over the last three decades or so is what has altered the perceptions over what is "normal" and what is not (IMO).

Generally, the whole room, or uncompartmentalized curbless shower concept can be managed by either, segregating toilet(s), bidet(s) and urinals to separate compartmentalized "toileting" rooms or closets, OR by using to the wall not floor draining fixtures for same; or if space and distance allow, "invisible" demarks of distance and changes in slope for un-compartmentalized "curbless" showers within overall uncompartmentalized full "bathroom groups".

Many bathrooms with pre-esisting "tub/showers", even smaller ones, can be fit with a curbless larger shower. Simply swappling pre-hung door assemblies' hinges with Full-extension hinges on bathroom doors can sometimes make the unaccessible "bathroom" now accessible, sometimes removing and resetting door stop in addition to full extension hinges will "do the job" depending on floor plan, making even removal, enlarging door opening, and replacement with larger pre-hung door to the bathroom unnecessary. Sometimes relocating toilet to a corner (set 45 from walls) and an accessible wall mounted sink is employed at the same time.

As we live longer, keep our homes, and keep family members with special needs within family households, we adapt our living spaces more and more to those needs.

In this country, in general, showers are the preference by the majority daily hygene events, and baths less so.

HG, I used to do SRO and senior housing inspections. All the newer buildings had floor drains in the bathroom areas. Showers in bathrooms were floor grade for the most part for wheelchair access.
As you mentioned, this type of system has been around for awhile in various housing types. I would like to see it more in standard residential. I think it would alleviate a lot of the water intrusion issues that happen.
I've recommended this to small Condo buildings and everybody freaks out that its going to cost a fortune. Granted it will cost more than standard but it shouldn't cost that much more. The high bids that have come back seem to be due more to contractor inexperience rather than justifiable expense.

Thanks but I'm just looking for the "required" minimum depth of a pan if any exists.

Zero. None.

Requirements depend (on such things as the area, the max flow rate and number of shower heads; the slope and location of drain, the drain,vent configuration and rate) sufficiency of slope of area to drain containment and prompt drainage, presence of walls, surfaces, within spray or deflection (washed wall planes, curtains, shower doors) which may catch, concentrate and direct collections of water, etc.

As indicated, it may be zero clearance "depth" of an appropriately sloped transitioned area, away from walls or "end", i.e. free standing non-compartmentalized shower area which may or may not have a trough type drain system deliniating. Site-made "pans" are an everyday occurance even today.

Zero. There is no flat-out absolute requirement to have a "curbed" shower area, or a finished compartmented shower, or a pre-fabricated receptor, of any particular height walls, curbs or horizontal lips.

Thanks HG, that was the anwswer I was looking for.

Originally Posted by Marc M

Thanks but I'm just looking for the "required" minimum depth of a pan if any exists.

Yes and no.

There is no minimum depth of the shower pan, there is a minimum height of the shower pan and there is a minimum depth of the shower drain.

From the IRC:
- P2709.1 Construction. Shower receptors shall have a finished curb threshold not less than 1 inch (25 mm) below the sides and back of the receptor. The curb shall be not less than 2 inches (51 mm) and not more than 9 inches (229 mm) deep when measured from the top of the curb to the top of the drain. The finished floor shall slope uniformly toward the drain not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) nor more than 1/2 inch (13 mm), and floor drains shall be flanged to provide a water-tight joint in the floor.

Okay, so we have a curbless shower (actually, there is still a "curb", the curb is simply the floor level - note in the above code section the code's use of "curb threshold", while we are discussing the more commonly used term of simply "curb", but it is also the "curb threshold"), the top of the drain must be AT LEAST 2 inches down from the curb ... i.e., the curb is at least 2 inches high - above the shower drain.

Even better, fantastic. Thats what I was looking for. I suppose it's knowing the IRC cover to cover.

Originally Posted by Jerry Peck

Yes and no.

There is no minimum depth of the shower pan, there is a minimum height of the shower pan and there is a minimum depth of the shower drain.

From the IRC:
- P2709.1 Construction. Shower receptors shall have a finished curb threshold not less than 1 inch (25 mm) below the sides and back of the receptor. The curb shall be not less than 2 inches (51 mm) and not more than 9 inches (229 mm) deep when measured from the top of the curb to the top of the drain. The finished floor shall slope uniformly toward the drain not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) nor more than 1/2 inch (13 mm), and floor drains shall be flanged to provide a water-tight joint in the floor.

Okay, so we have a curbless shower (actually, there is still a "curb", the curb is simply the floor level - note in the above code section the code's use of "curb threshold", while we are discussing the more commonly used term of simply "curb", but it is also the "curb threshold"), the top of the drain must be AT LEAST 2 inches down from the curb ... i.e., the curb is at least 2 inches high - above the shower drain.

Am I understanding P2709 correctly?

If the requirement is a minimum 2 inches fall, "curb to drain", then any curbless shower "PAN" must have the drain located at least 4 feet from the entry point, (@ 1/2" maximum fall).

So it requires any curbless shower with a center drain to be at least 8 feet wide. Right?

At a safer 1/4 inch fall, now it's 16 feet wide. Not reasonable for most seniors or homes.

Am i missing something

Originally Posted by Gerald Star

Am I understanding P2709 correctly?
.
.
.
Am i missing something

You can have a 6 inch long slope, right? And it can still slope 1/4" per foot , right?

"the top of the drain must be AT LEAST 2 inches down from the curb ... i.e., the curb is at least 2 inches high - above the shower drain"

Yes, but how far must that 1/4" per 6 inch slope run out in order to have the required minimum 2" top of curb to top of drain fall?

Originally Posted by Gerald Star

"the top of the drain must be AT LEAST 2 inches down from the curb ... i.e., the curb is at least 2 inches high - above the shower drain"

Yes, but how far must that 1/4" per 6 inch slope run out in order to have the required minimum 2" top of curb to top of drain fall?

Looks to me it's 4 feet. If so, a center drain curbless shower needs to be a minimum 8 feet wide.

Originally Posted by Jerry Peck

There is no minimum depth of the shower pan, there is a minimum height of the shower pan and there is a minimum depth of the shower drain.

From the IRC:
- P2709.1 Construction. Shower receptors shall have a finished curb threshold not less than 1 inch (25 mm) below the sides and back of the receptor. The curb shall be not less than 2 inches (51 mm) and not more than 9 inches (229 mm) deep when measured from the top of the curb to the top of the drain. The finished floor shall slope uniformly toward the drain not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) nor more than 1/2 inch (13 mm), and floor drains shall be flanged to provide a water-tight joint in the floor.

Okay, so we have a curbless shower (actually, there is still a "curb", the curb is simply the floor level - note in the above code section the code's use of "curb threshold", while we are discussing the more commonly used term of simply "curb", but it is also the "curb threshold"), the top of the drain must be AT LEAST 2 inches down from the curb ... i.e., the curb is at least 2 inches high - above the shower drain.

I guess I am not following your question/statement.

Let me restate

1. Assuming the minimum drop is 2" "top of the drain must be AT LEAST 2 inches down from the curb"

2. Assuming maximum allowable slope is 1/2" p/ft. "The finished floor shall slope uniformly toward the drain not less than 1/4 unit vertical in 12 units horizontal (2-percent slope) nor more than 1/2 inch (13 mm)"

3. And if that's true, then the minimum distance from entry of a curbless shower to the top of drain has to be at least 4 feet long. (2" / 1/2" = 4 feet) "a curbless shower (actually, there is still a "curb", the curb is simply the floor level"

4. So if all that is true, then that means "any" curbless shower that has a "center" drain must be a minimum of 8 feet, entry to rear wall. 4 feet to drain and 4 feet from drain to rear wall.

That's a sizeable shower for most seniors and houses.


This 46" x 46" square curbless shower with a center drain has a slope of 3/8" p/ft. It only has a total drop from curbless entry to top of drain of 3/4".
shower curbless.jpg

So if the rest of this bath floor is tiled and level to the adjoining bedroom I assume it doesn't meet code as the curb is not 2 inches higher than top of drain.

Okay, got it.

One code section many forget about is this one, and it is a very important one:
- From the 2015 IRC:
- - R104.11 Alternative materials, design and methods of construction and equipment.
- - - The provisions of this code are not intended to prevent the installation of any material or to prohibit any design or method of construction not specifically prescribed by this code, provided that any such alternative has been approved. An alternative material, design or method of construction shall be approved where the building official finds that the proposed design is satisfactory and complies with the intent of the provisions of this code, and that the material, method or work offered is, for the purpose intended, not less than the equivalent of that prescribed in this code. Compliance with the specific performance-based provisions of the International Codes shall be an alternative to the specific requirements of this code. Where the alternative material, design or method of construction is not approved, the building official shall respond in writing, stating the reasons why the alternative was not approved.
- - - R104.11.1 Tests.
- - - - Where there is insufficient evidence of compliance with the provisions of this code, or evidence that a material or method does not conform to the requirements of this code, or in order to substantiate claims for alternative materials or methods, the building official shall have the authority to require tests as evidence of compliance to be made at no expense to the jurisdiction Test methods shall be as specified in this code or by other recognized test standards. In the absence of recognized and accepted test methods, the building official shall approve the testing procedures. Tests shall be performed by an approved agency. Reports of such tests shall be retained by the building official for the period required for retention of public records.

Being as that section dictates, as you pointed out, a 4 foot distance to a drain which is recessed 2 inches below a curbless shower entry to maintain the maximum stated 1/2 inch per foot slope; or, that a 2 foot distance to such drain would necessitate that the drain only be recessed 1 inch below such curbless shower entry to maintain that same slope; and recognizing that a curbless shower entry is more subject to water leaking out of the shower than a curbed shower entry regardless of how much the drain is recessed below the shower entry; and recognizing that a slope of 1/4 inch per foot is sufficient for water drainage from the curbless shower entry; and also recognizing that a curbless shower entry may be intended for handicapped persons; and also recognizing that the maximum permitted cross slope for handicapper persons is 1/4 inch per foot - it is hereby approved that the shower drain is permitted to be recessed 1/2 inch below the curbless shower entry ... signed, Building Official.

Absolutely meets code.

FWIW: there is an excellent article, by Michael Mitchell the San Francisco chief plumbing inspector, in reevesjournal.com of feb 5 2015.
Mitchell discusses changes in the code to cater for walk-in non traditional showers.

cityofpaloalto.org has a pdf explaining what they want in a walk-in receptor, and the slightly different requirements for a factory built receptor and a site built receptor.
They use the terms dam or threshold.