Building & renovation
How much wood impregnant do you need?
How much wood impregnating stain for decks, cladding and outdoor timber.
Quick answer
Wood impregnants soak in rather than sit on top — so “coverage” is really how much liquid the timber drinks before the surface looks wet. Softwoods and rough-sawn cladding absorb more than planed hardwood; two coats on exterior joinery are normal.
Advanced settings
Paint needed
8.8 liters
- Cans to buy
- 4 × 2.5 L
Impregnants soak into the wood: yield depends on species and roughness. Two coats are common on decks and cladding exposed outdoors.
How it works
Default yield is 10 m²/L per coat, same family as interior paint, but use the absorbent surface factor for new deck boards or weathered gray wood. Reapply every 2–4 years on horizontal surfaces regardless of what the first job calculated. Browse deck impregnating stain rated for your exposure class (use class 3+ outdoors).
Grey, weathered deck boards drink the first coat — pressure-wash and let dry 48 h before you calculate litres. A wide deck brush pushes stain into grooves faster than a roller; wood deck cleaner on mouldy boards improves penetration so you are not just sealing dirt under the film. Wear chemical resistant gloves — many exterior stains are solvent-based.
Impregnant has one rule that ruins the job when it is ignored: whatever the wood has not drunk within about fifteen minutes has to be wiped off. Left there, it dries on the surface instead of in the fibre and stays faintly tacky for months, collecting dust and fingerprints — the sticky deck that people blame on the product. Go back over with a dry cloth on anything that still looks wet. And give the cut ends far more than the flat faces: end grain absorbs several times as much, and it is where rot starts on every fence post and every deck board.
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Frequently asked questions
Impregnant or varnish on a garden deck?+
Horizontal decks take sun and foot traffic — penetrating oil/stain is easier to refresh than a thick varnish that can peel. Varnish is better on vertical cladding and furniture. Size liters with this tool; plan maintenance, not a one-time purchase. South-facing decks often need recoating every 18–24 months regardless of the first tin size.
How long between impregnant coats?+
Follow the tin: often 12–24 h at mild temperatures. Second coat on still-tacky wood will not penetrate evenly. Do not calculate liters for same-day double flooding — two thin coats beat one heavy puddle.
Do I need to strip old stain first?+
If the old coat is sound and the same chemistry (oil-on-oil, water-on-water), clean and recoat. Flaking or incompatible layers need stripping or sanding back — your m² area stays the same but prep time doubles.
Is one coat enough on fencing?+
Vertical rough-sawn fence boards sometimes look acceptable with one heavy coat, but end grain and post tops still need two. Use one coat in advanced only if you are maintaining an existing saturated finish.
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