Garden Decking Stains, Treatments & Oils : Part 1 - Getting Started

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.