- Slope the ceiling slightly. If you don’t, any steam that condenses there will drip down onto your shoulders.
- Protect wood framing with sheets of 6-mil plastic stapled over studs and joists. Overlap all edges by at least a foot.
- Seal the seams between the concrete backer-board panels (which are unaffected by moisture) with mesh tape and thinset.
- Cover every inch of plastered area with a waterproof membrane. Use either two coats of a roll-on liquid polymer such which dries into a seamless, rubbery skin, or embed sheets of flocked polyethylene.
- Tile and grout as usual. If using stone, apply an impregnator to seal the stone. You’ll need to repeat this treatment every two years.
- Make sure you seal around any fixtures that penetrate the tile—including shower and steam heads, digital controls, and valves.
