bathroom wall material--easy question

Old 12-08-04, 01:51 PM
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bathroom wall material--easy question

Hi all-
Okay, I am brand new at this, but excited to learn a new skill. So I apologize for the really simple questions. This site is great! Context: I am just about to strip down my small bathroom's lathe/plaster walls (including around the tub/shower) and redo the whole thing...

1) From the studs out, what do I need to put on the walls? The bathroom is small enough that I don't mind making the entire room as waterproof as what will go behind the shower. On my bathtub/shower walls, I'm going to put up cultured marble. But from the studs to the marble, what do I need? It sounds like maybe a vapor barrier, then cement board, then the adhesive for the cultured marble??? I want this baby waterproof!

2)What is the best way to tear down a lathe/plaster wall to the studs?

Old 12-08-04, 02:16 PM
racer x
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Ah, another newbie. Now I don't feel so lonely! I'm in the middle of the same job minus the marble, add the ceramic tile. The cement board is for behind the shower. I used greenboard everywhere else. I read that a .4mm plastic sheet can serve as a vapor barrier but only necessary in the shower. Don't forget you need to insulate the tub flange so water won't wick up behind the marble. I used tar paper and a tube of tar in a caulk gun.

As far as the demo goes, all I used was a hammer, a pry bar, several masks, about four thousand garbae bags and a boat load of patience.

Hope this helps,
Old 12-08-04, 05:00 PM
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racer x and Oregonian,

Just some added notes here to ensure that things are done right.

Ceramic tile has long been a material of choice for use in bathrooms, kitchens, swimming pools, and other generally accepted "wet" areas. It provides a glazed, easily cleaned, and sanitary surface.

Through the first half of this century, ceramic tile was installed over a full bed coat of portland cement plaster in order to provide a durable, long-lasting tile substrate. The total system was comprised of materials that were certainly not detrimentally affected by water intrusion.

As gypsum drywall became more of a factor in the residential construction market, the extra expense of applying ceramic tile over a cement plaster bed coat became a budget problem. Gypsum panels as a substrate for ceramic tile were a natural. However the natural negative reaction between gypsum products and water was a big deterrent. Initial installation specifications for gypsum drywall as a ceramic tile substrate required the panels to be full size sheets to eliminate butt joints, a minimum 1/29 thick, and applied horizontally with the paperbound edge down toward the tub, shower receptor, or pan. A minimum 1/49 clearance or space was required between the edge of the wallboard and the tub, receptor, or pan to prevent capillary migration of water.

The gypsum drywall then had to be "waterproofed." This could be accomplished by one of two methods:
1. Skim coat—with the flat edge of a trowel a full 1/169 skim coat of an approved grade of tile adhesive was applied evenly to the entire surface to receive the tile. It was applied to the bottom edge of the wallboard and was to fill the cut-out spaces around soap dishes, pipes, towel bars, etc. This coating was allowed to stand at least 24 hours. After the skim coating had hardened so that it would not be grooved by the notches of a trowel, a bedding coat was applied over the lip of the tub forming a water dam behind the bottom edge of the tile.
2. Sealer—a waterproof sealant could be applied in lieu of the adhesive skim coat. It had to be specifically made for the purpose, and compatible with the tile adhesive. A heavy brush application of sealer was necessary, and included sealing all edges of cut-outs—and then the cut-outs were caulked with waterproof, nonhardening caulking compound.
The key to success of the drywall substrate for ceramic tile was to provide a surface that was impervious to free water intrusion and to provide seals against that occurrence at penetrations.

In the mid 1960’s U. S. Gypsum introduced a product called SHEETROCK® brand Gypsum Panels, Water-Resistant (W/R). This innovative gypsum product addressed the fact that water and gypsum were not friendly neighbors. The face and back papers were specially treated to provide water repellency and the core was treated with a water-resistant emulsion. The added water resistance eliminated the need for the extra skim coat of adhesive or the waterproof sealant. The face paper was made with a green color for product identity simplification to represent water-resistance, and the industry saw the birth of "green board."

Deterioration complaints due to water intrusion behind the ceramic tile dropped dramatically with the introduction of SHEETROCK® brand W/R Gypsum Panels. But the new product was not the full answer to water deterioration problems. If the ceramic tile grout cracks and lets water get behind the W/R gypsum panels, the W/R gypsum panels will eventually fail.

Portland cement basecoats have a long history of positive performance with ceramic tile finishes. Portland cement and water are compatible—the water certainly doesn’t "hurt" the cement. What would be more natural than a board product like gypsum board made from portland cement? Hence Durock Multi-Purpose Cement Board.

Since the portland cement composition of Durock Multi-Purpose Cement Board provides a material that can be exposed continuously to water without deterioration, it is ideal for extreme moisture-presence applications (see sidebar article on page 11). SHEETROCK® brand W/R Gypsum Panels can still be used in certain situations, particularly where exposure to water is occasional and indirect, i.e., residential applications.

Installing Cement Board
Installing and maintaining a substrate for application of ceramic tile is now possible without concern for water deteriorating the substrate. Both surfaces of Durock Multi-Purpose Cement Board can be used for application of ceramic tile. Typically the smooth side is used when type 1 organic adhesive is the choice for tile installation and the textured side used for thin-set type mortars. Cement board substrates are equally adapted to use on floors, which of course is not a good application for gypsum substrates.

Durock Cement Board provides a superior base for the application of ceramic tiles to walls, ceilings, and floors. Durock Cement Board satisfies the important criteria that should be considered in selecting a tile substrate:
1. The panel must have adequate strength and stiffness, in a wet and dry condition, to resist deformation under design loads when applied to framing at specified spacings.
2. The panel should be easy to handle, cut, and fasten. The panel, specified fasteners, and spacings must be capable of carrying the weight of the tile, mortar, grout, board, wind, or other service loads.
3. The panel must provide the required shear bond strength to secure the tile to the board, be dimensionally stable, freeze/thaw and fire resistant, and not delaminate, swell, soften, or deteriorate when exposed to water.
4. The panel should have national code acceptance and be recognized by the Tile Council of America (TCA) and the Ceramic Tile Institute (CTI) to assure the user that it meets the requirements of all the major code bodies and industry standards.
Durock Multi-Purpose Cement Board is accepted by all the Model Building Codes. Also, there are local code jurisdictions that are addressing the desirability of a cement board substrate via code restrictions. Many major builders and developers specify Durock Multi-Purpose Cement Board routinely as an assurance of long-term performance. Note that it is important that Durock Wood or Steel Screws be used to attach the board to framing to avoid the possibility of failure due to fastener pull-through.

Installing Water-resistant Gypsum Panels
1. If necessary, fur out studs around shower receptacle so that the inside face of lip of fixture will be flush with gypsum panels face.
2. Install appropriate blocking, headers or supports for tub and other plumbing fixtures, and to receive soap dishes, grab bars, towel racks, or similar items.
3. Do not use vapor retarders between water-resistant panels and framing.
4. Install receptors before panels are erected. Shower pans or receptors should have an upstanding lip or flange at least 1 inch higher than the water dam or threshold at the entry to the shower.
5. After tub, shower pan, or receptor is installed, place a temporary 1/4 inch spacer around lip of fixture. Cut panels to the required sizes and make the necessary cutouts. Before installing panels, apply thinned ceramic tile mastic to all cut or exposed panel edges at utility holes, joints, and intersections.
6. Install the panels perpendicular to the studs with the paper-bound edge abutting the top of the spacer strip. Fasten the panels.
7. For tile 5/8 inches thick or less, panels may be installed with stud adhesive to wood or steel framing. Apply one 3/8 inch bead to stud faces, two beads on studs where two panels meet. Drive nails or screws around the perimeter.
8. In double layer applications, both layers must be SHEETROCK® brand Gypsum Panels, Water-Resistant.
9. In areas to be tiled, treat all fastener heads with SHEETROCK® Setting-Type (Durabond 45 or 90) or Lightweight Setting-Type (Easy Sand 45 or 90) Joint Compound. Use the same joint compound with SHEETROCK® Joint Tape to finish joints.
10. For areas not to be tiled, embed tape with SHEETROCK® Setting-Type (Durabond 45 or 90) or Lightweight Setting-Type (Easy Sand 45 or 90) Joint Compound in the conventional manner.
11. Grout all tile joints carefully to avoid water leakage through the tile plane.

Hope this helps!
Old 12-09-04, 07:25 AM
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Outstanding! Thank you. Tom, can you give me more detail on what you mean by 'insulating the flange'? I understand you want the durock 1/4" up off the surface of the tub lip.

Are you saying to put a piece of tar paper between the flange of the tub (I assume the flange is the verticle part of the tub, a few inches high, to prevent water from spilling/seeping directly over the edge) and the durock? That sounds pretty good---do you need to do it all the way behind the wall of the shower?

Good stuff, I love learning from others.

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