A.Contributing editor Michael Byrne, an expert tile setter and consultant in Los Olivos, Calif., responds: While breezeway enclosures are good because they help shield walkways from precipitation and temperature extremes, they can also trap moisture. A floor that puddles is a nuisance and a safety hazard, and in the environment of an enclosed breezeway, chronic excess moisture can lead to mold and wood rot. So, depending on your breezeway's design and exposure, you may have to slope the walkway prior to tiling and provide a method of draining off excess water. And even without the need for a slope, scuppers, or a drain, retrofitting this installation for tiling will still require a waterproofing/crack-isolation membrane applied to the slab. Finally, if the crack in the concrete exceeds 1/8 inch wide or results in uneven concrete surfaces, the walkway should not be tiled at all.

Flat or sloped, all exterior tiled walkways need a waterproofing membrane. If sloped, the slope should allow the walkway to self-drain. I prefer to float a crowned, bonded latex mortar fill over a concrete slab, but many walkways are finished with the tiles sloped to one side only. Drainage is needed in either case; I recommend fitting the...

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