Synavax’s Crystal Clear Insulating Roof Coating can be applied to tile, wood-shingle, composite- tile, and metal roofs to protect against mold, mildew, moisture, and weathering from UV rays. Though the coating is described as “insulating,” the company offers no R-value or description of how it reduces heat transfer. The water-based, nontoxic, and low-VOC coating has a matte finish and is priced at $117 for one gallon. Synavax says the coating can’t be used on slurry or glazed tile. synavax.com