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Gallons of deck paint, solid stain or resurfacer for the deck, railing and stairs, with primer and cost.
With these inputs:
| Result | Value |
|---|---|
| Porch & floor paint needed | 2 gal |
| Surface to coat | 299 sq ft |
| Exact amount (2 coats) | 2.0 gal |
| Estimated cost | $90 |
| Deck floor | 200 sq ft |
| Railing (2 sq ft per foot) | 80 sq ft |
| Stairs (~4.6 sq ft per step) | 19 sq ft |
| Coverage used | 300 sq ft/gal per coat × 2 coats |
Coverage is a planning figure from typical manufacturer labels on smooth, sound wood; rough or weathered boards can take 25% more. Planning prices: $45/gal paint or solid stain, $55/gal resurfacer, $35/gal primer. Buy one extra gallon of the colour for touch-ups.
Deck paint, solid stain and resurfacer coatings are film-forming, so they go on in two coats and the coverage depends heavily on the product: a thick resurfacer covers about a quarter of what porch paint does. This adds the railing and stair surfaces to your deck area, applies the right coverage and coat count for the product, and gives the gallons, primer and cost to buy.
Divide the surface by the coverage and multiply by two coats. Porch and floor paint covers about 300 sq ft per gallon per coat, so a 200 sq ft deck with 40 ft of railing and four steps is about 298 sq ft of surface and just under 2 gallons for two coats. Buy 2 plus one for touch-ups.
Much less than paint: thick resurfacer or restore coatings are rated at roughly 75 sq ft per gallon for the two coats they need, about a quarter of what porch paint covers. That is why a resurfaced 200 sq ft deck with railings takes about 4 gallons where paint would take 2. They fill cracks and splinters, but they peel if the boards underneath are rotten.
Stain penetrates the wood and wears away gradually, so it is easy to recoat. Paint and solid stain form a film that hides worn or mismatched boards and lasts longer on vertical surfaces, but it peels when water gets under it and has to be scraped before recoating. Paint suits railings and older decks; penetrating stain suits floors on newer ones.
Prime bare wood, new pressure-treated lumber once it is dry, and any patched or stripped areas. A deck that was painted before and is still sound only needs cleaning and a light scuff. One coat of exterior primer at about 300 sq ft per gallon is enough; the calculator adds it when you choose to prime.
Two. Deck paint, solid-colour stain and resurfacers are all film-forming finishes, and their durability comes from film thickness, which one coat does not give. Let the first coat dry for the time on the can, usually 4 to 24 hours, and apply the second before the recoat window closes.
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