Shower Pan & Shower Pan Membrane Construction & Installation: Best Practices
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Shower pan choices, installation, troubleshooting: this article discusses the proper construction or installation of cement, pre-fab, or mortar-bed shower pans and shower pan membranes to build a leak-proof shower floor.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
Recommendations for Constructing or Installing Bath Shower Pans
This article series discusses current best design practices for kitchens and bathrooms, including layout, clearances, work space, and accessible kitchen and bathroom layout, clearances, turning space, grab bars, controls, etc. We include advice on choosing and installing kitchen countertops, cabinets, and kitchen or bathroom flooring, sinks, and other plumbing fixtures and fixture controls such as faucets. A list of kitchen and bath product manufactures and sources is included.
The fiberglass shower pan shown at left was placed and secured to the floor during bathroom construction, then protected from damage with cardboard pending installation of shower enclosure, plumbing, controls, and door.
Photo courtesy Galow Homes.
As explained in Chapter 6 of Best Practices Guide to Residential Construction:
A shower pan must be completely watertight and able to
hold pooled water should the drain get clogged.
Most are
built in place over a mortar bed with a waterproof membrane
liner.
However prefabricated setting beds have also
become available recently.
Guide to Using Prefab Cement Shower Pans
Our collapsing, leaking shower pan/floor installation (left) illustrates why site-built lead lined shower pans are a "lost art" and why most contractors opt for pre-fab shower pans of cement, fiberglass, or other materials.
For standard shapes and sizes,
one option is to install a prefabricated pan made from
40-lb polystyrene foam coated with a reinforced cementitious
coating that is ready to receive tile. These range in
size from 36x36 inches to 36x60 inches and come pre sloped
with a built-in drain.
One unit, called Pro-Form
(Bonsal American) is bonded to the subfloor with latex modified
thinset, coated with a liquid waterproofing
membrane, and is then ready to tile. As long as the subfloor
is sufficiently stiff to prevent flexing, these units
should perform well with 4x4–inch tiles. Smaller tiles
may exert too much of a point load for the underlying
foam, while larger tiles can cause problems with the slope
angle.
How to Install Prefab Plastic Shower Pans
A less expensive option is to
combine tiled walls with a one-piece fiberglass or acrylic
shower pan (not to be tiled). These are the same materials
used in one-piece shower or shower-tub units. A few companies
also sell stand-alone solid-surface shower pans.
Like other plastic units, these must be properly supported
underneath to prevent flexing and cracking. Some require
setting in sand, wet mortar, or plaster. In general, acrylic
units cost more than fiberglass but are stronger and less
prone to flexing and cracking.
How to Build Mortar-Bed Shower Pans & Install a Shower Pan Membrane
Built-in-place shower floors using
a mortar bed and modern waterproofing shower pan membranes can
provide many years of trouble-free service. For best performance
use a heavy-duty sheet membrane, such as 40-mil
Chloraloy (Noble Company), which is designed for use in
shower pans and similar applications.
To guarantee that any trapped water will drain properly,
the shower pan membrane is placed on a layer of latex-modified
mortar sloped 1/4 inch per foot toward the drain. Two-piece
clamping-type drains are designed to seal to the membrane
by compression between the upper and lower flanges (see Figure 6-41).
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Figure 6-41
[Click any image or table to see an enlarged version with additional detail, commentary & source citation.] |
A layer of sealant applied between the shower pan membrane and
lower flange serves as backup waterproofing. Weep holes
around the bottom of the drain, surrounded by pea gravel
or pieces of broken tile, allow any water that accumulates
to drain away (see Figure 6-42 below).
The shower pan membrane should run up all sides of the shower,
at least 3 inches above the height of the finished curb.
Secure the membrane to the framing with galvanized staples
or roofing nails along the top edge, being careful to
make no holes in the membrane any lower than 2 inches
above the finished curb.
At the inside wall corners, the
extra membrane material is not cut, but pleated and
folded over to lay flat against the framing. Avoid making
wrinkles here or along the bottom of the pan.
At the curb,
the membrane must be cut so it can fold over the top of
the curb. Seal these corner cuts with either prefabricated
“dam corners” or patches of membrane caulked in place
with Nobleseal 150, a high-performance Kraton-based
sealant.
Kitchen and Bath Product Manufacturers, Sources, Associations
Bonsal American
www.bonsal.com
Setting compounds, grouts, preformed shower pans, curbs,
and niches. Also, distributor of backerboards, isolation
membranes, and other tile-setting products
Color Caulk, div. of Roanoke Companies Group
www.colorcaulk.com
Color-matched caulking
Custom Building Products
www.custombuildingproducts.com
Elastomeric and liquid-applied membranes, self-leveling
underlayments, setting compounds, and grouts
Laticrete International
www.laticrete.com
Trowel-on membranes, self-leveling underlayments, setting
compounds, grouts, and sealants
Noble Company
www.noblecompany.com
CPE sheet membranes, trowel-on membranes, clamping
ring drains, and preformed slopes, niches, and curbs
Mapei
www.mapei.com
Trowel-on and sheet membranes, self-leveling underlayments,
setting compounds, grouts, and color-matched
sanded caulks
Custom Building Products
www.custombuildingproducts.com
Wonderboard cement backerboard, Easyboard cement and
polystyrene lightweight backerboard, and Rhinoboard
fiber-cement backerboard
Georgia-Pacific Gypsum
www.gp.com/build
Denshield gypboard backer with glass-matt facing
James Hardie Building Products
www.jameshardie.com
Fiber-cement backerboard
National Gypsum
www.nationalgypsum.com
Permabase lightweight cement and polystyrene
backerboard
Schluter Systems
www.schluter.com
Kerdi tile membrane goes directly over drywall or other
substrates
T. Clear Corp./Fin Pan Inc.
www.finpan.com
Util-A-Crete lightweight concrete backerboard
U.S. Gypsum
www.usg.com
Durock cement backerboard
W. R. Bonsal
www.bonsal.com
Extruded polystyrene backerboard with fiberglassreinforced
cement facing
-- Adapted with permission from Best Practices Guide to Residential Construction.
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Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.
- Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
- Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: ericgalow@gmail.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
 The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.
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- "The Elimination of Unsafe Guardrails, a Progress Report," Elliott O. Stephenson, Building Standards, March-April 1993
- "Are Functional Handrails Within Our Grasp" Jake Pauls, Building Standards, January-February 1991
- Access Ramp building codes:
- UBC 1003.3.4.3
- BOCA 1016.3
- ADA 4.8.2
- IBC 1010.2
- Access Ramp Standards:
- ADA (Americans with Disabilities Act), Public Law 101-336. 7/26/90 is very often cited by other sources for good design of stairs and ramps etc. even where disabled individuals are not the design target.
- ANSI A117.4 Accessible and Usable buildings and Facilities (earlier version was incorporated into the ADA)
- ASTM F 1637, Standard Practice for Safe Walking Surfaces, (Similar to the above standards)
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- ASHRAE resource on dew point and wall condensation - see the ASHRAE Fundamentals Handbook, available in many libraries. The following three ASHRAE Handbooks are also available at the InspectAPedia bookstore in the third page of our Insulate-Ventilate section:
- 2005 ASHRAE Handbook : Fundamentals : Inch-Pound Edition (2005 ASHRAE HANDBOOK : Fundamentals : I-P Edition) (Hardcover), Thomas H. Kuehn (Contributor), R. J. Couvillion (Contributor), John W. Coleman (Contributor), Narasipur Suryanarayana (Contributor), Zahid Ayub (Contributor), Robert Parsons (Author), ISBN-10: 1931862702 or ISBN-13: 978-1931862707
- 2004 ASHRAE Handbook : Heating, Ventilating, and Air-Conditioning: Systems and Equipment : Inch-Pound Edition (2004 ASHRAE Handbook : HVAC Systems and Equipment : I-P Edition) (Hardcover)
by American Society of Heating, ISBN-10: 1931862478 or ISBN-13: 978-1931862479
"2004 ASHRAE Handbook - HVAC Systems and Equipment The 2004 ASHRAE HandbookHVAC Systems and Equipment discusses various common systems and the equipment (components or assemblies) that comprise them, and describes features and differences. This information helps system designers and operators in selecting and using equipment. Major sections include Air-Conditioning and Heating Systems (chapters on system analysis and selection, air distribution, in-room terminal systems, centralized and decentralized systems, heat pumps, panel heating and cooling, cogeneration and engine-driven systems, heat recovery, steam and hydronic systems, district systems, small forced-air systems, infrared radiant heating, and water heating); Air-Handling Equipment (chapters on duct construction, air distribution, fans, coils, evaporative air-coolers, humidifiers, mechanical and desiccant dehumidification, air cleaners, industrial gas cleaning and air pollution control); Heating Equipment (chapters on automatic fuel-burning equipment, boilers, furnaces, in-space heaters, chimneys and flue vent systems, unit heaters, makeup air units, radiators, and solar equipment); General Components (chapters on compressors, condensers, cooling towers, liquid coolers, liquid-chilling systems, centrifugal pumps, motors and drives, pipes and fittings, valves, heat exchangers, and energy recovery equipment); and Unitary Equipment (chapters on air conditioners and heat pumps, room air conditioners and packaged terminal equipment, and a new chapter on mechanical dehumidifiers and heat pipes)."
- 1996 Ashrae Handbook Heating, Ventilating, and Air-Conditioning Systems and Equipment: Inch-Pound Edition (Hardcover), ISBN-10: 1883413346 or ISBN-13: 978-1883413347 ,
"The 1996 HVAC Systems and Equipment Handbook is the result of ASHRAE's continuing effort to update, expand and reorganize the Handbook Series. Over a third of the book has been revised and augmented with new chapters on hydronic heating and cooling systems design; fans; unit ventilator; unit heaters; and makeup air units. Extensive changes have been added to chapters on panel heating and cooling; cogeneration systems and engine and turbine drives; applied heat pump and heat recovery systems; humidifiers; desiccant dehumidification and pressure drying equipment, air-heating coils; chimney, gas vent, fireplace systems; cooling towers; centrifugal pumps; and air-to-air energy recovery. Separate I-P and SI editions."
- Principles of Heating, Ventilating, And Air Conditioning: A textbook with Design Data Based on 2005 AShrae Handbook - Fundamentals (Hardcover), Harry J., Jr. Sauer (Author), Ronald H. Howell, ISBN-10: 1931862923 or ISBN-13: 978-1931862929
- Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
- Building Research Council, BRC, nee Small Homes Council, SHC, School of Architecture, University of Illinois at Urbana-Champaign, brc.arch.uiuc.edu. "The Small Homes Council (our original name) was organized in 1944 during the war at the request of the President of the University of Illinois to consider the role of the university in meeting the demand for housing in the United States. Soldiers would be coming home after the war and would be needing good low-cost housing. ... In 1993, the Council became part of the School of Architecture, and since then has been known as the School of Architecture-Building Research Council. ... The Council's researchers answered many critical questions that would affect the quality of the nation's housing stock.
- How could homes be designed and built more efficiently?
- What kinds of construction and production techniques worked well and which did not?
- How did people use different kinds of spaces in their homes?
- What roles did community planning, zoning, and interior design play in how neighborhoods worked
- Humidity: What indoor humidity should we maintain in order to avoid a mold problem?
- ...
