"No rug is weatherproof, but a rug can use UV-treated polypropylene yarns to resist fading," Carmen Barbee, merchandise buyer for Ballard Designs, told Consumer Reports.
Even with moisture resistance, outdoor rugs can still cause mildew when left on patios for a long duration without time to dry off the surface, especially on unsealed concrete.
Rugs can protect wooden or brick patios from fading, but while the area under the rug doesn’t fade, the rest of the patio does, leaving a silly cookie-cutter shape.