black brown browns colors colours contours cover dips exterior grooves hard horny plates layers lines outlines pointed points protection rough shapes shell shelter sides solid strength strong textures tips tortoise tortoise shell tough white angles appearance building capping cleaning covered covering danger dangers ear protection edge external height high high-pressure improvement maintenance pressure pressure-cleaning renovating renovation repairs restoration restoring risks risky roof roof-area roofing rooftop safety skies sky spray sunlight sunshine tiles tiling tools water wet work workman