How do Ottawa painters prepare a previously stained deck for a fresh coat?

Deck refinishing is one of those jobs that Ottawa homeowners face every 2-4 years thanks to our punishing climate. A previously stained deck needs careful prep before re-coating -- skip the prep and your new stain will peel, flake, or wear through in a single season. Here's how Ottawa's experienced deck painters handle it.

Assessing the Current Stain Condition

Before doing anything, you need to figure out what you're working with:

Semi-transparent or transparent stain (you can see wood grain): These wear away gradually through foot traffic and UV exposure. Ottawa decks typically show gray, faded areas in high-traffic zones and better colour retention under furniture and along edges. If the stain is simply faded but not peeling, prep is relatively straightforward.

Solid stain or paint (opaque, no wood grain visible): These form a film on the surface that cracks and peels as the wood expands and contracts through Ottawa's -30 to +35 degree temperature range. Solid coatings on horizontal deck surfaces are the most failure-prone finish in our climate.

The water test: Sprinkle water on the deck surface. If it beads up, the existing stain is still repelling moisture and a new coat won't absorb. If it soaks in within 30 seconds, the surface is ready to accept stain (after cleaning).

Step 1: Clear and Inspect

Remove all furniture, planters, and grills. Then do a thorough inspection:

• Check for soft, punky wood by probing with a screwdriver. Ottawa decks take serious abuse from snow load and standing water -- deck boards over 15 years old often have rot at the joists and near the ledger board.
• Check for popped screws or nails. Freeze-thaw cycles push fasteners out of the wood. Reset or replace them.
• Look for mildew -- black or green spots, particularly common on north-facing decks and shaded areas. Ottawa's spring moisture creates ideal conditions for mildew growth starting in April.

Step 2: Strip or Sand the Old Stain

For peeling or flaking solid stain:
A deck stain stripper is the most effective approach. Products like Flood StripPeel, Defy Stain Stripper, or Ready Seal Stain Stripper ($25-$40 per gallon at Ottawa paint stores including Dulux on Gladstone or Cloverdale on Industrial) are applied, allowed to dwell, and then pressure washed off.

Apply the stripper with a pump sprayer, let it work for 15-30 minutes (follow the product label), and rinse with a pressure washer at 1,200-1,500 PSI with a fan tip. Work with the grain direction, keeping the nozzle 12-18 inches from the surface.

For worn semi-transparent stain:
Often you can skip stripping entirely. A good power wash with a deck cleaner removes surface grime and faded stain residue. Follow up with an orbital sander using 80-grit on any stubborn areas.

For severely failed coatings:
A belt sander or floor sander (rentable at Home Depot Innes Road for about $60-$85 per day) is sometimes necessary. Start with 60-grit and finish with 80-grit. This is labour-intensive but gives you a fresh wood surface.

Step 3: Clean with a Deck Wash

After stripping or sanding, the deck needs a dedicated deck cleaning solution:

• Oxygen bleach-based cleaner (like OxiClean or a purpose-made deck wash, $15-$25) removes mildew, algae, and oxidized wood fibres without damaging the wood or killing your landscaping.
• Avoid chlorine bleach on wood -- it breaks down lignin (the natural binder in wood fibres) and leaves the surface fuzzy and prone to premature failure.

Apply the cleaner, scrub with a stiff-bristle push broom, let it sit for 10-15 minutes, then rinse thoroughly with the pressure washer at 1,200-1,500 PSI.

Step 4: Brighten (Often Missed)

After cleaning, the wood often looks dull or gray. A wood brightener ($12-$20) containing oxalic acid restores the wood's natural colour and opens the pores for better stain absorption. Apply with a pump sprayer, let it work for 10-15 minutes, and rinse. This step makes a visible difference in the final result.

Step 5: Dry Thoroughly

This is where Ottawa's climate requires patience:

• Allow a minimum of 48-72 hours of dry weather before applying stain.
• The wood moisture content should be below 15% -- check with a pin-type moisture meter ($30-$50).
• May and June in Ottawa are ideal for deck staining: warm enough for proper stain cure, long enough days for drying, and before the peak summer humidity arrives.
• Avoid staining in direct hot sun -- the stain dries too fast and doesn't penetrate. Ottawa painters prefer morning applications on south-facing decks and afternoon on north-facing ones.

Step 6: Apply the New Stain

Once properly prepped, stain application is straightforward:

• Semi-transparent penetrating stain is the recommended choice for Ottawa decks. It absorbs into the wood, moves with seasonal expansion, and wears gradually rather than peeling. Products like Ready Seal, TWP, or Sansin ($50-$75 per gallon) are well-suited to Ottawa conditions.
• Apply with a stain pad, roller, or pump sprayer followed by back-brushing. Back-brushing works the stain into the wood grain.
• One to two coats depending on the product. More is NOT better -- excess stain that doesn't absorb will peel.
• Don't forget the end grain of deck boards -- these absorb the most moisture and benefit most from stain protection.

Professional Cost in Ottawa

Deck staining prep and refinishing in Ottawa typically runs:

• Small deck (under 200 sq ft): $600-$1,200


• Medium deck (200-400 sq ft): $1,200-$2,500


• Large deck (400+ sq ft): $2,500-$4,500

These prices include stripping, cleaning, brightening, and two coats of quality stain. Ottawa pricing runs about 10-15% below comparable services in the GTA.

For experienced deck painters and staining specialists in Ottawa, check the Ottawa Construction Network directory. And for questions about your specific deck situation, Ottawa Paint Contractors' Paint IQ is always here.