How’s your garden decking looking? Is it looking tatty, less than its best and in need of a good seeing to?
In our special series of three posts about wooden decking stains, treatments and oils, we’re looking at how to make your decking look beautiful and last longer, exploring the differences between the myriad of products on the market, their application and common-sense decking maintenance.
By the end of our third post, you’ll know exactly how to keep your softwood and hardwood decking in tip-top condition from one year to the next.
First… laying your decking the right way around
Did you know you were supposed to lay grooved decking face down? The smooth side is, believe it or not, less slippery than the grooved side, which is actually designed to face downwards. The smooth side also requires less oil than the grooved side because there’s a smaller surface area. Imagine a piece of concertinaed paper that is grooved but then stretched out flat… hey presto! It becomes bigger than when folded. Smooth decking is also easier to keep clean and finish. Apparently, the UK is the only country to predominantly ‘expose the grooves’.
About decking
Decking is both useful and good-looking in any garden but, left untreated and unloved, will soon start to look tired and worn. The good news? Even if your decking has suffered from the ravages of the British weather, it can be revived without too much fuss by simply following a few basic steps.
When it comes to treating decking, there are numerous factors to consider. In this article, we’ll address them all, but if you have a specific question, feel free to contact us.
Is your new wooden decking pre-treated?
Most new decking nowadays comes pre-treated with a wood preservative that offers protection against wood disease and insect attack. But few, if any, come ‘pre-finished’ with a decking oil or decking stain.
To check if your timber has been pre-treated, look for a green/brown tinge or a surface that’s darker than the inner cut face. Pre-treated decking is sometimes called tanalised timber, or tanalith, which is the industrial name for a wood preservative. If it has already been treated, it’s ready for finishing.
Decking treatment – Is a wood preservative necessary?
Although clear wood preservers don’t contain any pigments or dyes, the ingredients always influence the colour of the wood. If your decking is bare wood with nothing on it at all, applying a decking preservative comes highly recommended for a smarter appearance and a longer life.
What finish is currently on my old wooden decking?
If your decking has been finished already and just needs a makeover, you need to identify the wood’s existing finish. Most decking topcoat finishes fall into one of two categories: oils or sealers. Because manufacturers don’t always use this terminology on the tin, this will be helpful:
- Decking oils penetrate into the wood and become a part of it, with only a small amount remaining on the surface. The grain tends to show through very well and the wood retains its natural texture. Oil-based decking products are easier to maintain and repair, and most people also prefer to see the natural beauty of the wood grain rather than cover it up.
- Decking sealers bond and produce a film on the surface of the decking, much like a varnish or paint. Because sealers sit on the surface of the wood rather than penetrating it, the grain is covered up slightly or dramatically, depending on the product. The film actually looks like a semi-translucent paint and feels smoother than an oil, without that typical woody texture. Sealers can be problematic because they will at some point start to peel and flake. It’s just a case of when. When it comes to recoating, you have to remove all the flaky material first and can only use a similar product on top. If any flaky material remains, the finish tends to peel and flake faster because it’s sitting on top of an already unstable surface.
How to remove decking finishes
Once you’ve determined which finish is currently on your decking, it’s time to either prepare it for refinishing or remove it altogether to start fresh. Your decision depends on two things: what colour you want to achieve and which finish will give you what you want. Here’s a rundown of each method:
- Sanding is only practical if the decking is smooth, with no grooves, and you want to completely remove the decking sealer.
- Jet washing is a popular choice for removing decking sealers that have peeled or flaked with age. Decking oil finishes can also be cleaned this way, but you need to take care not to push the existing finish out of the wood and into surrounding plants, ponds and soil.
- Remove oil-based finishes with white spirit if you want to retreat your garden decking with a sealer. If you want to retreat a previously oiled exterior deck with a fresh coat of oil, you don’t need to remove all the existing oil. Just clean the surface with white spirit.
- Use a varnish stripper if you want to completely remove decking sealer and retreat it with an oil-based product.
In general, if the wood has been treated with a decking oil and you’re happy with the colour, it’s a simple matter of cleaning the decking and reapplying two or three coats of fresh oil.
It’s worth bearing in mind that the colour of the wood will influence the eventual colour of the finished decking. Using a cedar red decking stain, for example, will give you three distinctly different colours, depending on whether the wood is new and untreated, new and treated or old and untreated.
Hardwood decking or softwood?
Assuming the wood is either new or has had the previous finish removed, knowing what type of wood you’re dealing with helps you identify the best-performing wooden decking finish. Exotic woods like ipe and bangkirai are naturally very oily, as are many hardwoods, and decking sealers don’t perform at all well on oilier woods. If you don’t know the exact wood type, simply knowing whether it’s a hardwood or softwood will help enormously.
How to use oil-based decking products
Different hardwoods contain different levels of oil. If the hardwood is new or has only been felled during the last few months, it will contain more oil than if it was cut down three months, six months or two years ago.
Some woods, for example teak, remain oily for longer than others and remain weather-resistant for much longer than softwoods or less oily hardwoods. If your decking is teak, it may be best to do nothing for at least a year, then only apply one coat of decking oil or teak oil.
The best way of knowing whether wood is ready for oiling is to drop a small amount of water on the surface.
- If the water beads up and sits there, the wood is already nice and oily.
- If it sinks in and forms a blot mark, the wood needs oiling.
- If the water sits on the surface for half an hour or more, then starts to sink in, there’s already a reasonable oil content and your decking probably just needs one thin coat of fresh oil.
Alternatively, you can use a simple sight test: if the wood looks dry, patchy, black or grey, it is asking to be treated or oiled, although some people like the look of silvery grey, worn, weather-beaten wood.
If you’ve decided on an oil, the idea is to get as much of the product to sink into the wood as possible so it becomes completely water-repellent.
How to maintain decking
Next time, in Part 2 of our Complete Decking Guide, we’ll be taking a look at some of the more common decking problems that can occur, plus their causes and cures.
36 comments
I have a new deck of pressure treated pine, and there are some bright green stains around the knots from the treatment. How should I handle these when it comes to finishing the deck? Should I let the deck weather and hope the green stains disappear before applying a finish? Should I lightly sand them off at the risk of removing the treatment? Is either an oil-based or water-based finish better at concealing these green stains or allowing them to fade naturally?
Thanks so much!
Reply to Alex:
Hello there!
The green stains are caused by a preservative treatment put in the boards to protect them from rot and mould. This generally leaks out of the knots in the wood. You can clean these off with some Methylated Spirit directly before application of a decking oil or leave the boards to weather for a short period of time (4-6 weeks) and these will have faded or worn away in this time. Any coloured treatment is likely to discolour near these areas so covering them with a stain should really be avoided.
Thanks,
Samuel
Hello everyone, I have just built a new replacement deck in Balau which looks stunning in the wet. I would like to preserve the deep red colour as much as possible but realise eventually it will probably go grey like my previous Balau deck did. I have a conservatory built on the deck so they are very linked visually. I used 18 year old Balua vanished with 4 coats of Sikkens which is still beautiful and now the new deck matches when it is wet.
I had a bad experience on the last deck using an oil product which ended up a sticky film and took years to wear off. I am hoping there is a product that will provide UV protection, keep the colour longer and not become sticky or slippery. The 160mm Balau planks are groove up mostly and both plain and grooved are very slip resistant at the moment. Cheers Phil Hartle SO316NE
Reply to Phil Hartle:
Hello Phil,
Thank you for your question. Balau is often used because of its durable structure and appearance even with out a finish applied. It is of course a dense wood and so less willing to absorb oils that are applied. This does not mean that oils are not suitable and in fact I nearly always recommend oils for decking areas as the better and easier to maintain option.
It does need to be the right oil however, and I would always recommend an Osmo product for these types of wood. The Osmo Decking Oil (https://www.wood-finishes-direct.com/products/osmo-decking-oil) is a slightly thinner oil than many other decking oil brands and so more suited to these types of hardwoods. 007, from the Osmo Decking Oil range, is a clear option that will darken the wood and highlight beautifully the natural tones of the wood, resulting in that ‘wet look’ appearance. Or the Bangkiria 006 is a coloured option most suited for Balau and the addition of pigment will better slow down the silvering of UV damage. Both should be used in conjunction with the WR Base Coat (https://www.wood-finishes-direct.com/products/osmo-wr-base-coat)
So two thin coats of this can be applied to the wood, after a period of weathering, which needs to be around 12 weeks as a minimum. Then you are able to try a test area to ensure you like the result that will be achieved.
The previous issue you had with an oiled finish could be the result of the oil being unable to penetrate the surface of the wood, and this is usually the result of over application or the wood has not been weathered for long enough. And a regular clean to avoid the build up of algae will keep the wood slip resistant.
I hope all of that helps and if you have any questions at all please do not hesitate to get in touch via our contact us (https://www.wood-finishes-direct.com/pages/contact) page.
Kind regards Samantha.
I had decking fitted 3months ago that had been treated. I want to put a clear oil on and done a tester spot and the decking went green. What do you suggest I do or am I treating it too early.
Reply to nicola knox:
Good Afternoon Nicola,
Most exterior woods come pre treated or Tanalised, this is often green in appearance and is because of a copper content in the tanaliser, and over time the colour does wear away. Application of an oil to a new wood will highlight any colours, marks in the wood alongside the natural tones and grain.
There is not a lot you can do about this but do be assured that it will fade away over the course of the coming year, with out much reduction in the protective quality to the wood.
Kind regards Samantha
Hi i am putting down a new deck using tantalised boards which have a slight green tint from the preservative treatment i would like to protect them further and tint them to a light to mid brown colour, i do not want to use a paint type treatment as i have used these before and don’t like the appearance, is there a stain type treatment that can be applied by sprayer that is environmentally friendly, i know most of the older types of spray preservatives had some pretty unpleasant chemicals in and was wondering if the technology had moved on to effective but safe water based alternatives, also would you recommend leaving the decking down for a period of time to settle in before treating or is to ok to treat it straight away.
Reply to ian hosking:
Hi Ian,
You can use a wood preservative such as Barrettine Premier Universal Preserver (https://www.wood-finishes-direct.com/products/barrettine-premier-universal-preservative) to further protect the wood from biological threats such as mould, algae, wood rot and insect attack. Once treated and fully dry (24 to 72 hrs), use a lightly tinted / pigmented decking oil to achieve the colour you are looking for. Decking Oils are an excellent choice as they are very easy to apply and maintain. They help to keep the wood nourished and supple and provide excellent weather resistance. Ideally, a fresh maintenance coat should be applied in Spring and Autumn. A couple of good options are Manns Premier UV Decking Oil (https://www.wood-finishes-direct.com/products/manns-premier-uv-decking-oil) or Ronseal Decking Oil (https://www.wood-finishes-direct.com/products/ronseal-decking-oil). Alternatively, you can find our full range of decking oils here (https://www.wood-finishes-direct.com/collections/decking-oil).
I wanted to get some advice from you please. Every year, I scrub my decking clean with warm water and mild detergent and then after they are dry, I apply Ronseal Decking Oil. This year, I applied it twice – once in April and again in late September. When I was hand cleaning the deck in September, I didn’t notice any rot at all.
Last week, I noticed rot, images are below:
https://imgur.com/I4F9mEY
https://imgur.com/6WK249L
https://imgur.com/HzqdJov
My neighbours who have never cleaned their decking never applied any protection and have green or algae-like coating on their decks don’t have rot, which is odd. I don’t wish them to have this problem, but it’s perplexing that I apply protection and I get the rot.
I wanted to ask – what would you suggest as remedies? I am thinking of allowing the decking to dry from rain, then apply anti-rot treatment to the affected areas (which are quite small), then apply decking oil again. But, I think it is likely that the decking oil repelled water and caused it to accumulate at nail heads and small cracks which caused it. Most of the rot is at nail heads.
So I will need to apply something on the nail heads perhaps.
What, if any, would your advice be?
I am also thinking of stripping off the old with White Spirit so the rain water does not ‘sit’ on top on the surface and find it’s way to the nail heads.
Thank you
Reply to Joshua:
Hello Joshua,
Frustrating for sure when you put so much work in. It could be a number of factors that include the types of wood, position, surrounding environment. Areas exposed to dampness, such as large foliage or woodlands nearby can wear quicker. My advice would be to continue with your good care and maintenance.
Applying a Wet Rot Wood Hardener (https://www.wood-finishes-direct.com/products/ronseal-wet-rot-wood-hardener) around the area of the nail heads could help it will impact on the Oil that you are applying however and the oil may not penetrate the wood in these areas and you could have a slight variance in appearance.
Stripping oil can be a little difficult and time consuming, a pressure washer can be an effective way to clean and strip the decking, take care not to hold the nozzle too close however as this can damage the wood and cause splinters.
I hope that helps and if you have any further questions or need any more advice on products please feel free to email me at wood@finishes.direct
Kind regards Samantha.