Guide to Finishing Western Red Cedar - Bear Creek …

1 Guide toFinishing Western Red CedarGuide to Finishing Western Red CedarAcknowledgement:Much of the text of this brochure has been excerpted with permission fromFinishes for Exterior Wood published bythe Forest Products Society, Madison,Wisconsin. The Western Red Cedar LumberAssociation gratefully acknowledges thesociety s cooperation and performs better with a protective finishWood differs from other common building materials inthat it is a natural biological such, andbecause of its chemical and physical makeup, wood issusceptible to deterioration due to the effects of theenvironment and other agents.

2 The results of which canbe diminished by applying suitably formulated protectivecoatings or level of protection requireddepends upon the extent to which the wood is exposedand the severity of the species of wood in lumber form possess bothnatural and manufacturing characteristicsthat affect the choice, application anddurability of finishes. Naturalcharacteristics rangefrom seasonalgrowthpatterns,grain and theoccurrence ofknots, to the exudationof pitch, resin and watersoluble characteristicsinclude growth ring orientation resultingfrom the sawing process, surface texture,type of knot, planing, and moisture toFinishing Western Red CedarAmong all the softwood species.

3 Western Red Cedar is considered to have the very best finish-retention stains in contrasting colors thoroughly hide the grain andnatural tones of Cedar but retain the wood s surface Red Cedar has unique finish-retention abilitiesThe most important characteristics of Western Red Cedar (hereinafter abbreviated to Cedar ) that contribute to itsexceptional ability to accept and retain many differenttypes of finishes are its outstanding dimensional stability,fine texture, a pattern of growth that results in narrowbands of summerwood, and freedom from pitch stability is related to the wood s less dense the wood, the less it tends to shrink andswell in response to changes in moisture content.

4 Cedaris a low density wood exhibiting excellent to the general coarseness of the woodsurface, primarily caused by the sawing, planing orsanding of growth, or springwood and summerwood, isthe annual increments or bands of tree growth. Cedar hasa lower percentage of summerwood than most or resin can be found in most softwoods but isabsent in Cedar . However, water-soluble extractives whichgive Cedar heartwood its natural decay resistance control duringmanufacture improves Cedar s Finishing characteristicsCedar produced by members of the Western Red CedarLumber Association is well-manufactured under strictquality manufacturing processes, however,may affect the performance of coatings.

5 Surface texture influences the choice of finish thatshould be applied to provide the best finishes such as penetrating stains are preferredfor textured surfaces, whereas paint systems are moresuitable for smooth-surfaced content may increase or decrease according tothe environment. Finishing wood that is obviously wetmay increase the risk of coating failure. It is best to finishcedar when its moisture content has stabilized at thelevel that will prevail during the service life of of the WRCLA exercise rigid in-mill quality controls throughout the Cedar manufacturing Today s Cedar markof quality used exclusivelyby WRCLA members isan assurance that theproduct is strictly gradedfor its intended end practices influencethe performance of finishesThe moisture content of wood at the time ofconstruction and during the structure s lifetime is themost important factor impacting upon the performanceof

6 The finish. Good construction practices are critical tothe prevention of excessive moisture build-up in it is not within the scope of this publication todescribe in detail the many construction techniquesnecessary to maximize performance, the following briefchecklist should prove helpful. More comprehensiveinformation can be found in the WRCLA publicationInstalling Cedar Siding. Use stainless steel, hot-dipped galvanized or aluminumfasteners. Proper flashing methods should be used in all aspectsof construction, including those not directly related tothe siding and trim.

7 Provide adequate overhangs at eaves and gables. Install drip caps over windows and door frames. Allow at least 6 inches clearance between bottom ofsiding and the groundline. Install vapor retarders on the warm side of walls tominimize condensation in walls. Vent high humidity areas such as kitchens, laundriesand bathrooms. Vent attics and prevent unsightlystains, only corrosion-resistant hot-dippedgalvanized, aluminum, orstainless steel fastenersshould be used with steel is the siding with a factory applied machine-coat of primer and/or topcoat keeps its long lasting good looks.

8 Some applicators offer long termperformance warranty Finishes forCedar Siding and Trim6 Cedar should not be left to weatherEven though Cedar weathers over time to an attractivesilver-gray patina that has a certain architectural appeal,research chemists and wood scientists stronglyrecommend that some form of protective finish beapplied to prevent surface surfaces provide a poor substrate for a few weeks of exposure will decrease Cedar sability to hold a finish. Once the finish-wood interfacefails, the coating will debond, blister, crack, flake or longer the period of weathering, the more rapidly thefinish may weathering of Cedar can be accomplished byapplying a commercially prepared bleaching stain whichis essentially a water-repellent finish containing pigmentsand other finish is most effective on tex-tured maintain a uniformly gray wood surface,bleaching stain may have to be re-applied coloration of newly milled Cedar can beretained by applying finishes that contain ultravioletblockers.

9 Finishes containing both an effectivemildewcide and ultraviolet protection are these finishes contain a low percentage of solids,they tend to be high maintenance. Penetrating oil-basedstains or light-pigmented natural tones can also beapplied to provide uniform color and protect the : Cedar should notbe left unfinished for 6 to 12months as suggested by some finish manufacturers and Expected Service Life of Exterior Finishes for Cedar (1)On Planed (Smooth) Vertical Grain CedarOn Textured CedarFinishSuitabilityExpected Life (years)SuitabilityExpected Life (years)Water-repellent preservativeand oil (2)High1-2 High1-2 Semi-transparent stain (3)Moderate1-3 High2-4 Paint (4)Highup to 10 Highup to 10 Solid color stain (4)Moderate3-5 High4-6(1) Data compiled from research observations.

10 Expected life predictions are for an average location in the continentalUnited States. Expected life will vary in extreme climates or exposures such as desert, seashore, and deep woods, oraccording to the building s orientation.(2) Development of mildew on surface indicates need for cleaning and possible refinishing.(3) Follow manufacturer s recommendations for number of coats.(4) Expected life of two coats: one primer and one top coat. Applying a second top coat will increase the life of the accepts many types of finishesThe choice of an exterior wood finish for Cedar dependsupon the desired appearance and the degree of protec-tion required.