Deck Cleaning & Sealing Cost

Frequently asked questions

How much does it cost to have a deck cleaned?

A contractor typically charges $1.20 to $3.00 per square foot for washing a deck, so $230 to $580 on a 192 square foot deck. Stripping an old failed finish costs more, often $2.50 to $5.00 per square foot, because it is slow work and the chemicals are harsher. DIY materials for the same deck run $40 to $110.

Can I pressure wash a deck?

Yes, carefully. Use a wide fan tip, keep the wand moving, work with the grain, and stay under about 1,500 psi on softwood — pressure-treated pine and cedar furr and gouge easily, and the damage is permanent. Many professionals now soft-wash with a cleaning solution and low pressure instead, which is gentler and works better on mildew.

How often should I clean my deck?

Once a year is the right cadence for most decks, usually in spring before the season starts. Decks under trees or on the shaded north side of a house need it more often, because that is where mildew and algae take hold. Composite decking still needs cleaning — it does not rot, but it grows the same surface mould.

What is the difference between deck cleaner and brightener?

A cleaner removes dirt, mildew and the grey oxidised surface layer; it is usually alkaline. A brightener is an acidic rinse — often oxalic acid — that neutralises the cleaner and restores the wood's colour and pH so stain penetrates evenly. Skipping the brightener after an alkaline cleaner is a common reason a fresh stain job looks blotchy.

How much does it cost to clean and seal a deck?

About $3.50 per square foot for a professional clean and one coat of sealer or semi-transparent stain, and around $5.50 when the boards also need sanding or an old finish stripped. That is roughly $700 and $1,100 on a 200 square foot deck. Doing it yourself costs about $1.20 per square foot in cleaner, brightener and stain — around $240 for the same deck.