Defect Problems of Cedar Roofing Shingles

Examine fire resistance treatment carefully. Fire risk is the principal defect of cedar shingles regardless of quality. The best fire retardant is one that is pressure applied into the wood rather than just sprayed. This treatment darkens the color of the shingles but they weather down to a gray color.

Look for shingles that are free from knots and are cut along the grain if your budget allows. Heartwood shingles have an edge grain that is tight, straight and stable. Sap wood shingles often have a slash grain cut that is visible as a wavy grain on the shingle surface. This type of wood is very prone to splitting and warping.

Nail zinc or copper strips at the ridge cap of the shingles. Rainfall will react with the metal to form a mild solution of zinc or copper sulphate and carry it two or three feet down the roof. This provides resistance to moss growth. Use rust-free nails. An application of a solution of zinc or copper naphthanate also retards moss growth.

Use the brush to apply a single coat of bleaching oil -- a mixture of linseed oil and bleach crystals -- to the shingles to protect them from rot and mold. Allow to dry for three or four days before fitting them on the roof. The bleaching oil turns the shingles into a gray color.