Installing Hardibacker board in Shower?HELP

Old 07-23-07, 11:29 AM
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Installing Hardibacker board in Shower?HELP

I had my plumber built the pan and now need to install the Hardiboard. I'm unsure how high to keep it from the rubber pad and how low can I go to screw in into the studs. Can someone pleae help me.
Old 07-23-07, 12:25 PM
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First a couple questions...
1) Is the liner installed over a sloped mud floor or is it flat on the subfloor?
2) Is there blocking between the studs at the bottom plate to help support the lower edge of the cement board and liner?
3) Is the liner wrapped fully around the curb and up the jams at least 3"?
4) Are there any nails in the pan that would be lower than 2" below the completed curb height?
5) Is there a bench in this shower?

All these questions will help determine if there are any steps to redo or if there are any additional techniques you will need to make a leak free shower.

BTW, for the intersection between the wall and the curb, there are preformed dam corners. If your plumber made his own, slide a paper towel under the intersection and let a slopping wet rag sit over the liner joint. If the towel gets wet, you can count on your curb rotting out. 24 hour water tests really don't test that section of the pan.
Old 07-24-07, 06:34 PM
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Thanks for the help Tilebri.

I had my plumber install a new drain and the shower pan. It's fully wrapped up the 1x6 jams and it nailed in place. No nails are lower than 5 inches from the bottom of the pan. The liner is on the concrete floor and nothing else is done. I want to install the hardibacker board on the walls, the studs are exposed now. I would like to put a corner bench in the shower if possible. THe shower is 3' x 5'.
Old 07-25-07, 02:51 PM
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I think Tilebri was concerned as to whether the shower pan is constructed properly. Check out this link for proper shower pan construction.

Sounds like you might be missing a preslope there.
Old 07-26-07, 05:24 AM
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Yup, no preslope under the liner and seems your liner should be going up the walls a bit more too. Two things in your favor though, liner material is pretty inexpensive and over a slab, your preslope layer can be feather edged at the drain when latex additive is used in the preslope bed mix. While you are replacing the liner, you can hit the studs with a planer or sander to remove enough material from the studs so that the liner is flush with the face of the studs. Cement board overlapping the liner not only causes the botom to buldge as it passes over the liner, but also can result in abrasive wear on the liner.

Too bad plumbers don't like to follow what's in their own code books. All that matters to them is that it doesn't leak when tested though about 50% of the verbage is dedicated to ensuring both proper drainage and drying out. Fill you pan with water and see all the water sitting in the pan when the test plug is pulled. That's your shower swamp that will fester all kinds of organic growth. That standing water in a properly constructed shower with a preslope will not only drain out to dry but any water within the pan will regularly be replaced with fresh water.

As for the bench, there is no better shower bench product than "better bench" from Innovis corp, and many local tile dealers will carry them. Wood framed benches require a bunch of other waterproofing steps that could be problematic later.

Just for your info, here's the shower pan code:

"412. 8 When the construction of on-site built-up shower receptors is
Permitted by the Administrative Authority, one of the following means shall
Be employed:
(1) Shower receptors built directly on the ground:
Shower receptors built directly on the ground shall be watertight and shall
Be constructed from approved type dense, non-absorbent and non-corrosive
Materials. Each such receptor shall be adequately reinforced, shall be
Provided with an approved flanged floor drain designed to make a watertight
Joint in the floor, and shall have smooth, impervious, and durable surfaces.
(2) Shower receptors built above ground:
When shower receptors are built above ground the sub-floor and rough side of
Walls to a height of not less than three (3) inches (76 mm) above the top of
The finished dam or threshold shall be first lined with sheet plastic*,
Lead* or copper* or shall be lined with other durable and watertight
All lining materials shall be pitched one-quarter (1/4) inch per foot
(20. 9 mm/m) to weep holes in the subdrain of a smooth and solidly formed
Sub-base. All such lining materials shall extend upward on the rough jambs
Of the shower opening to a point no less
Than three (3) inches (76 mm) above the top of the finished dam or threshold
And shall extend outward over the top of the rough threshold and be turned
Over and fastened on the outside face of both the rough threshold and the
Non-metallic shower sub-pans or linings may be built-up on the job site
Of not less than three (3) layers of standard grade fifteen (15) pound (6.8
Kg) asphalt impregnated roofing felt. The bottom layer shall be fitted to
The formed sub-base and each succeeding layer thoroughly hot mopped to that
Below. All corners shall be carefully fitted and shall be made strong and
Watertight by folding or lapping, and each corner shall be reinforced with
Suitable webbing hot-mopped in place. All folds, laps, and reinforcing
Webbing shall extend at least four (4) inches (102 mm) in all directions
From the corner and all webbing shall be of approved type and mesh,
Producing a tensile strength of not less than fifty (50) psi (344. 5 kPa) in
Either direction. Non-metallic shower sub-pans or linings may also consist
Of multi-layers of other approved equivalent materials suitably reinforced
And carefully fitted in place on the job site as elsewhere required in this
Linings shall be properly recessed and fastened to approved backing so
As not to occupy the space required for the wall covering and shall not be
Nailed or perforated at any point which may be less than one (1) inch (25.4
Mm) above the finished dam or threshold. An approved type sub-drain shall be
Installed with every shower sub-pan or lining. Each such sub-drain shall be
Of the type that sets flush with the sub-base and shall be equipped with a
Clamping ring or other device to make a tight connection between the lining
And the drain. The sub-drain shall have weep holes into the waste line. The
Weep holes located in the subdrain clamping ring shall be protected from

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