Stain or paint for a wood deck in Ottawa?

For a wood deck in Ottawa, penetrating finishes, meaning semi-transparent stains and water-repellent preservatives, are what the USDA Forest Products Laboratory recommends over paint and solid stains. Paint and solid stains are rated low suitability for decking because film-forming finishes are very difficult to maintain on a horizontal walking surface, and penetrating finishes have to be refreshed every few years.

Here is what the FPL figures look like in practice, keeping in mind these are US data and that expected life depends on climate and exposure:

• Water-repellent preservative: 1 to 2 years before recoating
• Semi-transparent stain on new, smooth-sawn boards: 2 to 3 years
• Semi-transparent stain on weathered or saw-textured boards: 3 to 6 years
• Tinted deck finish on new smooth-sawn boards: 1 to 2 years
• Tinted deck finish on weathered or saw-textured boards: 2 to 3 years

The condition of your boards matters: the FPL figures give longer intervals on weathered or saw-textured boards than on new smooth-sawn ones. The FPL's main point on longevity is that keeping water beading on the surface, rather than soaking in, is the best way to prevent checking and splitting, which is the most common reason wood decks are replaced, not decay.

If your deck was built before 2004, Health Canada notes it may contain CCA-treated lumber. For those older boards, Health Canada suggests applying a sealant every year using an oil- or water-based stain, and specifically says paints and other film-forming finishes are not recommended. For newer treated lumber, use the FPL decking intervals above and follow the product label.

One practical note: if you are refinishing an existing deck rather than finishing new boards, follow the label of the finish you choose for application conditions, coverage and recoat timing.

We found no City of Ottawa permit or zoning rule about refinishing a deck. If you are planning a new deck or replacement alongside the finishing work, the permit rules, inspections and material requirements would apply to the structural work.

When you are comparing quotes for any deck work that goes alongside refinishing, ask each builder to spell out exactly which line items, such as railings, stairs, removal of an existing deck, permit drawings and foundation work, are included in the price and which are not.