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Larch oil for decking

Updated: 23 October 2026

The boards are down, and you want one oil before the next wet month. Larch oil for decking is a fair job when the timber is sound and you have accepted a warm tint. It is a poor job on brand-new resinous larch, on a deck you have just jet-washed, or when you wanted a non-slip clear coat. This page stays on horizontal boards. The tins and prices are on the [larch oil comparison](/hub/paints-and-varnishes/larch-oil). The Products Compared editorial team wrote this on 19 October 2026 from Osmo’s UK instructions and the amazon.co.uk files. We did not measure slip on a wet terrace.

The boards are down, and you want one oil before the next wet month. Larch oil for decking is a fair job when the timber is sound and you have accepted a warm tint.

Our top picks

Osmo Osmo 009 larch oil 0.75 litre

Best overall

Osmo Osmo 009 larch oil 0.75 litre
7.6/10about £23.82
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Osmo Osmo 009 larch oil 2.5 litres

Rank 2

Osmo Osmo 009 larch oil 2.5 litres
8.4/10about £72.31
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Bondex Bondex larch oil 3 litres

Best value

Bondex Bondex larch oil 3 litres
8.0/10about £30.36
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On this page
  1. 1.New larch and grey larch
  2. 2.Grooves, edges, and the tin that runs out
  3. 3.Water, slip, and a second product
  4. 4.What an oil will not do to the boards

New larch and grey larch

New larch will not take oil evenly. Osmo UK says wait at least six weeks so surface resins can weather. Grey larch that is still firm is a different start. Clean it, let it dry, and oil if you want the warm tone back. Do not jet-wash. If a board is soft under a screwdriver, replace it.

Grooves, edges, and the tin that runs out

Ribbed larch drinks more than a planed face. Osmo prints about 24 square metres per litre and also 35 ml per square metre. Those rates do not convert into each other. One UK review oiled about 15 square metres, sides included, and had about a litre left from the 2.5 litre tin. Grooves take the first coat. Bondex prints 22 square metres per litre. German-language reviews, not UK customers, say bare wood came in under that. Ignore a field that says 30 litres. The title is 3.0 litres. Oil the cut ends you can reach. Osmo says recoat when wear shows, with one coat on the worn track rather than a full rebuild.
Osmo Osmo 009 larch oil 0.75 litre

Testsieger

Osmo Osmo 009 larch oil 0.75 litre
7.6/10about £23.82
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Water, slip, and a second product

A water-beading coat is not a dry deck. Osmo says horizontal boards hold standing rain, which is why a clear UV oil is a poor deck coating. Keep the gaps between boards clear. Osmo 009 is not the anti-slip coat. More grip, in Osmo’s system, is Anti-Slip Decking Oil 430 as the second coat over a coloured oil, not instead of it. That tin is outside this set. Bondex’s family text says the oil is only partly non-slip, and not for wood-plastic composite. If you need grip more than a deeper honey colour, plan 430 before you buy 3 litres of tint.

What an oil will not do to the boards

Forest Research, citing BS EN 350, classes larch heartwood as 3–4 against fungi and sapwood as 5. An oil does not move a board up that scale, and these listings are not an HSE product-type 8 wood preservative. Osmo’s two to three years wording on sheltered recoats belongs to their UV oils, not as a guarantee you can paste onto 009. Recoat when the wear shows. Call someone in when joists are decayed, when you need a fire specification, or when a failed film has to come off the whole deck.

Common questions

How long do I leave new larch before the first oil?
At least six weeks, which is Osmo UK’s figure for new larch before Decking-Oil. Pressure-treated wood is longer: about 12 weeks of heavy rain or about six months of light rain on Osmo’s page. Oil earlier and the resin pushes the coat into patches. The six weeks is weathering, not a cure that makes the timber more durable.
How much oil does a grooved deck use?
More than 24 square metres per litre. A UK review put most of a 2.5 litre Osmo tin onto about 15 square metres once the sides were included, with about a litre left. Bondex’s 22 square metres per litre is a listing figure that rough-wood reviews undercut. Buy for ribs, cut ends, and a second thin coat, then keep the spare for the worn track next year.
Will the oil stop the boards going grey?
It slows the look of greying compared with bare wood or with Osmo’s clear 007, and a darker pigment does more of that than a clear oil. It does not freeze the new-board colour, and UK reviews say 009 itself adds a tan or orange cast. When the walking line wears through, you clean and recoat. You do not get a stated number of years from these listings.
Why does rain sit on the surface afterwards?
Because a water-repellent oil beads, and a deck is flat enough to hold that water in the grooves. Osmo cites standing rain as the reason a clear UV oil is a bad fit on horizontal wood. Brush pooled water off if it sits for hours, and keep the board gaps open. Beading is the claim on the tin. A pond on the boards means the drainage is flat, not that you need a thicker coat.
Is an oiled deck slippery?
It can be, especially when wet. Osmo 009 is not the anti-slip product. Osmo points you to Anti-Slip Decking Oil 430 as a second coat over the coloured oil. Bondex’s own family text says the oil is only partly non-slip. If grip is the main requirement, decide on that second product before you commit to a strong tint you then have to walk on.
Can I jet-wash the grey off first?
Osmo says not to. A jet raises the grain and soaks the grooves, so you wait again for the wood to dry before any oil will take. Clean with a brush, let the boards reach the moisture cap on your tin, and then oil. Grey, firm wood does not need to be blasted back to bare fibres.
Do I oil the underside and the edges?
Oil the edges and the cut ends you can reach. The UK review that used most of a 2.5 litre tin had included the sides, which is why a top-face sum ran out. The hidden underside of a board on joists is usually left, because you cannot coat it properly once the deck is down and trapped oil will not dry. Ends and the first few centimetres of the edge are the parts that take the weather.

Related pages

How to apply larch oil

Larch oil or clear decking oil

Larch oil buying guide

Larch oil

Best larch oil: review file, trial, or price/litre

Sources

Public sources from the research digest, last checked on 22 October 2026. Shelf prices and star lines are the amazon.co.uk figures in the display file, scraped 19 October 2026. The price band is this set, not a market average. No listing was lab-tested.

  1. Osmo UK Decking-Oil (retrieved 22 October 2026)
  2. Osmo UK: clear finish on decking (retrieved 22 October 2026)
  3. Forest Research FRRP035: BS EN 350 classes for larch (retrieved 22 October 2026)
  4. HSE biocidal product types (retrieved 22 October 2026)
  5. VOC in Paints, Varnishes and Vehicle Refinishing Products Regulations 2012 (retrieved 22 October 2026)
  6. Consumer Rights Act 2015, section 11 (retrieved 22 October 2026)
  7. East Sussex Fire and Rescue Service: fire hazards of linseed oil (retrieved 22 October 2026)
  8. TRADA: specifying timber exposed to weathering (retrieved 22 October 2026)
  9. amazon.co.uk listings in this set (retrieved 19 October 2026)