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Estimate cost to clean and re-seal your deck.
With these inputs:
| Result | Value |
|---|---|
| Estimated cost | $700 |
Most decks need re-sealing every 2–3 years to prevent rot and UV damage.
Cleaning is the cheapest maintenance a deck gets and the one that decides whether the next finish holds. Price depends on the deck's size, its condition and whether the job is a wash or a strip. This estimates both the DIY materials and a contractor's price, and shows the annual cost of keeping on top of it rather than letting it go.
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.
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.
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.
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.
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.
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