Liquid Waterproofing and Vapor Barriers for Tile Showers
Keeping water where you want it.
By Rob Robillard
When remodeling a shower, most people are more concerned with the aesthetic aspects—tile color, fixture selection, glass door style—and pay little attention to construction methods. They assume that the contractor will do things right. However, a lack of waterproofing measures is clearly evident in the many showers I remodel every year. Some contractors waterproof correctly, but most don’t.
When folks get excited about choices in aesthetics, they often overlook how the contractor deals with water infiltration as well as the other hidden details needed to ensure a long-lasting and quality job.
Over the past 20 years the tile industry has shown great advances in waterproofing tile-related products, especially with methods of constructing tile showers. Paint-on liquid waterproofing products now enable contractors and DIY’ers to waterproof a shower easily and efficiently. These paint-on systems, when combined with a copper shower pan and proper substrates, all work as a system to keep water in the shower and out of the wall cavity.
In my neck of the woods there are several liquid-based, “paint on” waterproofing products available. Some of the more popular brands are Laticrete Hydo Ban, Custom RedGard and MAPEI AquaDefense.
My local tile store sells Hydro Ban, which comes in a gallon bucket and is applied with a paint roller or brush. Hydro Ban can be used over cement board, fiber-cement board, concrete, mud work, and other areas where you would be installing tile. It’s a two-coat system and costs nearly $100 a gallon, with 5-gal. containers being better priced.
Hydro Ban is a thin, load-bearing waterproofing/crack-isolation membrane that does not require the use of fabric in the shower wall field, coves or corners. The product is a single-component, self-curing liquid rubber polymer that forms a flexible, seamless waterproofing membrane and bonds directly to a wide variety of substrates. It also has an anti-fracture protection of up to 1/8 in. over shrinkage and other non-structural cracks.
Where TO Use It
Liquid waterproofing should be applied to all surfaces in the shower area that meet water or moisture. I basically paint all of the surfaces that will receive tile in the shower, including horizontal areas exposed to moisture such as shower benches, shelving, half-walls, niches and especially the shower floor.
When installing horizontal surfaces in a shower such as shelves, half walls and niches, ensure that these surfaces all have a slight pitch to the drain in addition to applying waterproofing. These surfaces are extremely susceptible to leakage, and the pitch ensures positive drainage while the liquid waterproofing prevents moisture from getting past the tile and grout.
Liquid waterproofing is an outstanding redundancy barrier to the tile installation and allows you to skip the plastic sheeting behind your substrate. (Note: I still recommend installing a vapor barrier behind the substrate, and if you plan on installing a steam generator, you will definitely need a vapor barrier.)
Most of us hate reading instructions, but I highly suggest that you follow the manufacturer’s instructions for the brand and type of waterproofing that you are using. With some waterproofing, the companies will want you to use a special fabric, along with the liquid, over the whole surface. Some will require the fabric to be used in all corners, while some don’t require it at all.