Finishing Exterior Wood

Finishing exterior wood is highly dependent on moisture content, type of wood, surface preparation, application method and finishing system used. It is recommended that all exposed wood members should be given a water repellent treatment coating prior to its installation. Follow these simple tips to have a better exterior wood finished.

Moisture

• Finishing your exterior wood will be poor if the wood moisture content is too high.
• Dark types of wood such as western red cedar, can discolor finishes if the wood is not dry when the finishing process is started.
• Look for wood that it is easier to finish like, western red cedar and redwood.

Paint

• Avoid painting or staining wood immediately after it has been installed. Sometimes wood gets wet or humid during the transportation or installation to the construction site.
• Brush application is more effective than spray or roller application.
• Primer and finish coating must be from the same manufacturer.
• All-acrylic latex solid-color stains are generally superior to oil-based solid-color stains on exterior wood when two coats are applied.
• When paint is used, it is recommended that two coats of all-acrylic top-coat paint applied over a stain-blocking acrylic latex primer lasts longer than other paint systems for exterior wood.
• Oil-based paint films usually provide the best moisture shield protection, but they tend to become brittle and are more likely to crack and peel.
• It is recommended the use of a paintable water repellent preservative as the first coat.

Surfaces

• Steel wool and wire brushes should not be used to clean surfaces to be finished.
• If two wood surfaces will be in contact and trap moisture these surfaces should receive a coating of preservative to prevent moisture problems associated to the contract between wood members.
• Exposed wood surfaces should receive a water repellent preservative coating.
• Water repellent preservatives are recommended for all exterior wood because they reduce moisture absorption, shrinkage and cracking.
• Exposed (non-contact) surface joists, framing and decking should be coated on all sides with a paintable water repellent preservative.
• Allow to dry wood surfaces that have been washed.
• Sanding, scraping, brushing or wiping may be necessary to clean the surfaces.