Some sections of old, unpainted shingles and siding may look darker than others. This discoloration is most likely caused by excessive tannins leaching from the wood and mildew growth. You’ll have to remove the mildew and prime the wood with a stain-blocking primer. You can prime and paint new shingles as soon as you’ve installed them, which is preferable since weathering can quickly alter the paintability of wood. You’ll have to recondition the wood fibers if you haven’t finished or painted cedar shingles within two weeks. Powerwashing old shingles is not recommended. Weathering makes them soft, and it’s almost impossible to avoid gouging them, and it’s equally difficult to properly dry the water forced under them. Editor’s tip: If you choose to stain cedar rather than paint it, there’s a few things you should know. Staining cedar siding differs from application of paint and other finishes. Stains dry rapidly, and fresh stain applied over dried stain will show lap marks. Editor’s tip: If you choose to stain over painted cedar shingles, you should know a few things. Staining cedar siding differs from the application of paint and other finishes. Stains dry rapidly, and fresh stain applied over dried stain will show lap marks. To properly stain cedar shingles: Editor’s tip: If you choose to spray either primer or paint on your shingles, apply the coating evenly and from different angles. Work in sections of about 20 square feet and back brush the coating immediately, so it gets worked into the shingle fibers and the recesses between them.
