Deck or patio gray and discolored
moderate 2–5 h
Tools: garden hose with a jet nozzle or a pressure washer with a 40° tip, stiff deck brush, pump sprayer, bucket, eye protection and gloves · Materials: oxygen-bleach deck cleaner (sodium percarbonate), deck brightener (oxalic acid) for wood, deck stain or sealer, concrete cleaner for patios
Steps
- Sweep and clear the deck, cover nearby plants with plastic, and wet them down; cleaners and stain run-off scorch leaves.
- For wood or composite, mix an oxygen-bleach cleaner, spray it on, let it sit 15 minutes without drying, then scrub with the grain and rinse.
- If pressure-washing wood, keep a 40° tip 30 cm (12 inches) from the boards at 1,200 psi or less and keep the wand moving — a closer or narrower spray raises the grain and leaves stripes.
- For concrete or pavers, use a surface cleaner attachment or overlapping passes, and spot-treat oil with a degreaser first.
- On wood, apply a brightener after cleaning to neutralise the cleaner and lift the grey; rinse and let it dry for 48–72 hours.
- Stain or seal on a dry, shaded day: test the wood by sprinkling water — if it soaks in within a minute, the boards are ready to take stain.
Stop and call a pro if
- boards are soft, spongy or the fasteners are rusted through — that is rot, not discolouration
- the deck is more than a metre off the ground and the railings or ledger board move when pushed
- the previous coating is peeling paint that may be lead-based (homes before 1978 in the US)
What a pro does that you can't
A pressure-washing service uses a surface cleaner and the right pressure for the material, and a deck contractor replaces rotted boards and re-stains with a sprayer for an even coat.
DIY cost: $40–120 in cleaner, brightener and stain