Wood used outdoors has a lot to put up with, especially rain (lots of it for a lot of the year) and heat (some of the time), in fact, it often has to put up with rain and heat alternating over short periods of time. In addition to stress from the weather, it can also be vulnerable to attack by insects. A good exterior wood preservative will help to protect your wooden furniture and extend its useful lifespan.

Types of exterior wood preservative

When you set aside all the marketing, there are basically just two types of exterior wood preservative, solvent based and water based. Solvent-based exterior wood preservatives are believed to be absorbed slightly better by the wood, however, these days many people opt for water-based exterior wood preservatives because they are rather more environmentally-friendly, as well as a bit easier to use.

Both solvent-based exterior wood preservatives and water-based exterior wood preservatives can be covered with a suitable top-coat, such as wood oil, stain, varnish or paint. This is highly recommended as it helps to seal in the wood preserver and also add an extra layer of protection.

In all honesty, most exterior wood preservatives contain much the same ingredients regardless of whether they are solvent-based or water-based, the differences between the best brands and the lesser brands tends to be more about the quality and exact quantities of ingredients used rather than the nature of the ingredients themselves. There is, however, one ingredient which you may want to look out for and that is wax.

The good news about wax is that it provides wood with a little bit of extra protection against weathering. The bad news about wax is that it does not combine well with water-based paints and most shed paints are water-based. Therefore, if you have set your heart on painting your wood, then you would probably want to look for a wax-free wood preservative, but if you’re happy to use another form of top coat, then the extra protection of wax could be very useful.

Best Wood Preserver

In a change to how we usually write these articles, we’re going to go ahead and give you a run down of what we consider to be the best wood preservers on the UK market and, in particular, what we think is the best clear wood preserver, the best exterior wood preservative and the best wood preservative for sheds. We’ll then give you some tips on how best to use whatever product you choose.

Editors Pick

RONSEAL 5L Total Wood Preserver

Runner Up

Cuprinol 5L Wood Preserver

Best Budget

Everbuild 5L Wood Preserver

Cuprinol Ducksback 5 Year Waterproof for Sheds and Fences, 5 L - Forest Oak

We’re generally rather cynical about products which claim to be designed for use on sheds as a lot of them are simply regular exterior wood preservatives which are being marketed to a specific niche. Cuprinol Ducksback, however, is different and the reason it’s different is because it is enriched with wax.

As we mentioned previously, wax-enriched exterior wood preservatives will limit your options regarding your choice of top coat, however, in the case of sheds we think it’s a reasonable trade-off. The way we see it, sheds are big-ticket items and if any part of them gets compromised, you could well be looking at replacing the whole shed (whereas with, say, a fence, you could just repair the damaged part).

Another argument for using a wax-enriched exterior wood preservative for a shed is that sheds typically hold items such as bicycles and/or gardening equipment, which can be expensive and inconvenient to replace if they become damaged through water getting into the shed.

In addition to being wax-enriched, Cuprinol Ducksback is non-drip, low-odour and safe around plants, pets and children. Like the Barrettine it is designed to work without the need for an additional top coat, unlike the Barrettine, however, we do feel comfortable about this claim, thanks to the wax and the many, many happy customers who can testify to its efficiency.

Everbuild LJUN05 5Ltr Lumberjack Triple Action Wood Treatment, Red

This is basically the same product as above but in red.

Barrettine Premier Wood Preserver Dark Brown 5l

This exterior wood preservative is described as being water repellent and, according to Barrettine, it does not require a top coat. We’re not that brave and would, instead, suggest that this would be a good option to use in particularly wet areas, with an extra waterproof coat on top.

One interesting point about this wood preserver is that although it is coloured (and the colour has good UV resistance), it is actually semi-transparent, so you can still enjoy your wood’s natural grain.

Although this wood preserver is solvent-based, the odour is reasonable and it does a good job of protecting wood against both rot and insects.

Bartoline Creocote Light Brown 4 Litre

Up until 2003, creosote was the standard treatment for exterior woods and it did a very effective job of protecting wood against the weather, fungi and insects. In 2003, however, the Health and Safety executive banned the retail sale of creosote due to evidence of it being a cancer risk. It is now only available to trade users and in the sort of quantities which would be massively excessive for domestic use.

If, for some reason, you are set on having your exterior wood treated with genuine, old-school, creosote, you will need to contact a professional and have them do it for you. If, however, you are happy to use a product which has much the same look and standard of performance as old-school creosote but is much more enviromentally-friendly and much less hazardous to health (both human and animal), then we think you could be very happy with Bartoline Creocote.

This product is definitely for exterior use only, the odour is far too powerful for indoor use, but outside it’s fine. The colour deepens over the course of a few weeks, so if you’re disappointed, to begin with, hold off using more coats until you see how it ages. After a while, you’ll get to a rich, warm, mid-brown tone and if you want to go a bit darker, you can apply another coat and/or use another product on top.

Best clear wood preserver

We’d recommend the Cuprinol clear wood preserver for light tasks and then either the Everbuild or the Ronseal for heavier tasks, depending on whether you wanted a solvent-based clear wood preserver or a non-solvent-based clear wood preserver.

Best exterior wood preservative

Being old-fashioned, we’d say that Bartoline Creocote was the best exterior wood preservative of them all, but that’s probably because we’re of an age where we remember the days when old-school creosote was the standard treatment for all exterior woods. Setting that aside, we’d say any of these options would do a decent job, so your choice would probably depend on the specifics of the job.

Best wood preservative for sheds

Basically we’d say that either the Bartoline Creocote or the Cuprinol Ducksback was the best wood preservative for sheds, depending on whether you wanted to stick as closely as possible to traditional creosote or use a more modern product, which also offers excellent performance.

Using your wood preserver

Now that you’ve chosen your wood preserver (and possibly even ordered it), it’s time to go over the practicalities of using it. The key point to understand about all wood preservers is that they prevent damage, they do not (cannot) reverse it. Hopefully, the timber you wish to treat will already be in good condition, but if not then you need to deal with whatever the issue is before you apply the wood preserver.

We’d generally recommend giving the surface a good clean and replacing any decayed wood. For sheds, you might want to invest in a specific shed-cleaning product (and although it’s a separate topic, now might be a good time to check the condition of the roofing, as it would be rather ironic if you protected the timbers only to have water leak through the roof covering).

You may also want to rub down the timber with methylated spirit and give it a light sanding, but when you’re dealing with large areas, especially exterior wood, many people skip this step and that’s usually fine. We would, however, suggest that you double-check on your product’s can before taking a final decision.

Once you’ve applied your wood preserver (as many coats as required), you’ll probably want to put on a top coat and here are your main options.

Wood oil

Wood oil is a very nourishing product which really soaks into the wood to keep it full of healthy moisture and hence reduce the chances of it splitting. The nature of wood oil is such that it generally needs to be replenished fairly regularly, but if you have expensive wooden items, it can be more than worth it, especially since wood oil will bring out the natural beauty of the wood grain.

Wood stain

Wood stain is very similar to wood oil in that it also soaks into the wood to provide moisture and nourishment and, as such, does need to be replenished fairly regularly. The key difference is that, as its name suggests, wood stain actually alters the colour of the wood.

Wood varnish

Wood varnish does not sink into the wood and hence does not really provide anything in the way of moisture and nourishment. It does, however, provide a very robust, protective top coat and, in particular, can be waterproof, which wood oil and wood stain are not. Varnishes are usually solvent-based and so should work with wood preservers which contain wax although it’s recommended to check on the can.

Paint

Paint is essentially varnish with pigment in it, however, paint can be solvent-based or water-based. The former will generally be fine on top of wood preservers which contain wax (although again, always check the can), but the latter is unlikely to do a good job anywhere near wax.