One benefit of installing Western red cedar siding is the beauty of its natural finish. But some homeowners may desire—or feel the need—for painting cedar* siding. And by paint, we mean an opaque exterior finish—not a solid color stain.
Detailed answers are provided verbatim by Paul Mackie of the Western Red Cedar Lumber Association (WRCLA).
Why Paint Rather Than Apply Other Surface Treatments?
Details: The type of finish selected is driven by style preference, and truly what one wants the siding to look like and frequency of re-finishing.
Western Red Cedar siding finished on all six sides with a stain blocking primer and top coated with 100% acrylic latex paint has the longest expected service life for the coating system. Factory-applied finishes of this type are available in most market areas.
Is There a "Painted Cedar" Style or Is This Just About Practicality?
Short Answer: Yes, there is a style. It is not all about protection.
Details: In many markets, like New England for example, painted siding is the preferred ‘look’.
Beyond that, Western Red Cedar has multiple advantages over other cladding options because it’s natural, sustainable and a renewal product. It’s easy to install and is available in almost unlimited sizes and patterns for those that want a unique ‘look’.
Can You Paint Cedar Without Priming It First?
Short Answer: Yes, but it is strongly discouraged.
Details: A two coat system, primer with a paint top coat, will have a significantly longer service life than will a single coat of paint (or solid stain). Paint without a primer applied to weathered wood will have adhesion difficulties.
Are There Any Painting Techniques That Work Better For Cedar? For Example, Spraying vs. Hand Brushing vs. Rolling?
Short Answer: Hand-brushing is recommended.
Details: For refinishing, hand-brushing is always preferred. If one chooses to spray apply, best results will be achieved by back brushing the finish during application. It is likely that hand-brushing will get more paint on the wood.
Is There an Optimal Window of Time For Painting Cedar?
Short Answer: Paint within 2 weeks. Wait no more than 12 weeks.
Details: Many don’t know that Western Red Cedar has a natural resistance to rot, decay and insect attack. For best results, if paint is the selected top coat, fresh siding should be pre-primed on all six sides with a stain blocking primer and top coated with 100% acrylic latex paint. Alkyd-oil primers are recommended, but one may choose a high-quality latex primer as long as it contains stain blockers.
Allowing fresh siding to “weather” for as little as two weeks negatively affects coating adhesion. Test results from the Forest Products Testing Lab (run by the USDA for the Forest Service), show that after 12 weeks of exposure to sunlight, cedar siding has lost 50% of its ability to hold a film forming coating system like primer and paint.
There is a sample of Western Red Cedar siding on the test fence at the testing lab in Madison, Wisconsin. It was pre-primed on all six sides (including the ends), top coated with two coats of paint and placed in a frame.
It has never been re-coated, shows no degradation of the coating system and has been on the test fence for more than 24 years. Other samples were allowed to weather for 3 months, 6 months, 9 months and 12 months before being primed and painted.
The longer the siding was allowed to weather, the sooner the coating system failed. And in all of those cases, it failed to start at the end grain where the siding abutted trim because the ends of the siding had not been primed.
Can Extremely Old Cedar Be Painted?
Short Answer: Yes, but it requires heavy preparation. Even then, the paint is not expected to last long.
Details: Surface preparation is key to success when dealing with weathered wood.
The siding must be free from mold, mildew, and dirt. Loosened (photo degraded) surface fibers and any loosened remaining finish must be removed prior to re-finishing.
Sanding is an option on smooth face siding and commercial strippers/restorers are available to accomplish this task.
Does Vertical Grain Cedar Hold Paint Better Than Flat Grain?
Short Answer: Yes.
Details: Vertical grain cedar, because of cell structure orientation absorbs alkyd-oil, stain blocking primers better than flat grain cedar.
However, knotty cedar holds these primers well because most knotty cedar siding patterns have a textured or re-sawn face.
Can You Use Self-Priming Paint With Cedar?
Short Answer: WRCLA has no data about this.
Details: I have not seen any test data on the supposed self-priming paints. Factory finish warranties provided by primer and paint manufacturers apply to cedar siding that has one coat of primer and one or two top coats of paint.
* For the purposes of this interview, the abbreviated terms “cedar” and “red cedar” refer to the same product: Western red cedar.