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What it costs to clean, seal or stain a deck, and how often it comes round again.
With these inputs:
| Result | Value |
|---|---|
| Estimated cost | $143 – $281 |
| Finish needed | 2 gallons |
| Redo every | 2–3 years |
| Cost per year | $48 – $141 |
| Deck surface | 192 sq ft |
| Railing surface | 80 sq ft (40 ft × 2) |
| Total area to coat | 272 sq ft |
| Coverage assumed | 200 sq ft per gallon, 1 coat |
| Finish | $76 – $136 |
| Cleaner and brightener (1 gallon) | $32 – $55 |
| Brushes, pads, tape and plastic | $35 – $90 |
Coverage on decking is always worse than the can claims, because the label figure assumes smooth new lumber and a deck is neither. 200 square feet per gallon is a realistic working number for weathered exterior wood; buy one extra gallon rather than run out mid-board and leave a lap mark. The cost-per-year line is the one worth comparing — a solid stain costs more per application but comes round half as often as a clear repellent. Prices are national estimates.
Sealing is the cheapest thing you will ever do to a deck and the one that decides how long it lasts. This prices the whole job — cleaner, brightener, the finish itself and labour — from your deck's area and railing length, then shows the annual cost once you account for how often each product type has to be redone.
For a 16 by 12 ft deck with 40 ft of railing, a DIY semi-transparent stain job runs roughly $160 to $330 including cleaner and sundries. A contractor typically charges $600 to $1,100 for the same deck in weathered condition, more if an old peeling finish has to be stripped first. Per square foot of coated surface, professional work lands around $2.20 to $3.90.
Take the deck area, add two square feet for every linear foot of railing, and divide by about 200 square feet per gallon for semi-transparent stain on weathered wood. A 192 square foot deck with 40 ft of railing works out at 272 square feet of surface — two gallons. Buy the extra gallon; running out halfway across a board leaves a permanent lap line.
It depends on the product, not the calendar. Clear water repellents need doing every year, transparent toners every one to two, semi-transparent stains every two to three, solid stains every three to five, and deck paint or a resurfacer every five to eight. Horizontal surfaces in full sun always fail first, so the deck floor will need attention before the railings do.
Yes, every time. Stain bonds to wood fibre, not to the grey oxidised layer, mill glaze or mildew sitting on top of it, and finish applied over a dirty deck lifts within a season. Wash with a deck cleaner, follow with a brightener if the wood is weathered, and let it dry for at least two clear days before the first coat.
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