Everyone has heard of wood preservers but what are they, why are they so important and how do they work?
Although wood is an amazingly versatile and durable material, it can be susceptible to deterioration especially where mould, algae, fungi and wood-boring insects are likely. The best way to protect and preserve wood, including timbers that have been tanalised or pressure-treated is to use a wood preservative.

In past years, treatments such as creosote and engine oil were used to preserve exterior timber, however, as a greater understanding of the toxic nature of these products became known many were banned or restricted for commercial use only by strict government legislation. Thankfully, todays domestic wood preservers are safer for both the user and environment.
Types of wood preservative
Most wood preservatives nowadays are manufactured with similar ingredients due to the government led restrictions, however the formulas and the strength of those ingredients do vary. In layman terms:
- Clear preservers help retain the natural appearance of the wood
- Coloured preservatives act as a dual purpose treatment and stain that change the colour of the timber
- Solvent-based formulas have been around longer and are known for their penetrative properties
- Water-based treatments confirm to strict V.O.C (Volatile Organic Compounds) regulations being imposed by UK, European and Worldwide governments, making them safer for the environment
Why use a wood preservative?
In short, wood preservers help extend the useful life of wood by preventing wood rot and decay caused by mould, algae, fungi and wood boring insects. Interior and exterior wood that has been preserved, treated and maintained can last for many 100s if not 1000s of years, making it a very eco-positive option.
How do wood preservers work?
The key ingredients of wood preservers are biocides and insecticides with the most commonly used being Permethrin. Permethrin is an insecticide in the pyrethroid family. Pyrethroids are synthetic chemicals that act like natural extracts from the chrysanthemum flower. Other common ingredients include Iodo propynyl Butylcarbamate and Tebuconazole. Most modern wood preservers are safe for humans, animals and plants when dry, meaning that they can be used on sheds, fences, wooden trellis, dog kennels, stables, joinery and more.
Are wood preservers an all-in-one solution?
Although wood preservers are great at protecting wood from biological threats, they only offer limited weather protection and direct contact durability. Some wood preservers contain a small amount of wax which means that rainwater will initially bead and run off treated wood. Surfaces treated with just a wood preservative however, will likely need re-coating every couple of years. Ideally, wood that has been treated with a preserver should also be treated with a suitable top coat such as an wood oil, wood paint or wood varnish. These top-coat products seal in the preserver and provide protection against weathering and wear from direct contact.
If overcoating a wood preservative with a water-based paint or varnish, it’s important to select a preserver that does not contain wax.
5 of our top selling wood preservers
Although we sell dozens of wood preservatives, here are just a few of our best selling products.
Barrettine Premier Wood Preserver
Barrettine Premier Wood Preservative offers microporous protection against wood rot, fungi, decay and mould as a deep penetrating solvent-based formula with wax and resin ingredients that help with water repellency. Due to this we only recommend using a solvent-based oil, varnish, stain or paint as a top coat if you wish, as water-based top coats will not adhere to the wax and resin base. Available in clear and an attractive range of wood tone colours.
Customer Review – Barrettine Premier Wood Preserver
The product is easy to apply, provided you don’t overload the brush and soaks into the wood. The boards on the house had two coats 3 years ago and still look good with little sign of green fungus (shady side). My neighbour has now decided to use it on his property.
Ronseal Total Wood Preservative
A highly penetrative, solvent-based formula Ronseal Total Wood Preserver is perfect for use on all exterior timbers including garden sheds, fences, joists, doors and window frames.
Customer Review – Ronseal Total Wood Preservative
Used for both my deck and my fence. Good coverage and easily applied using a brush. Natural colour which brings out the grain. Would recommend.
Cuprinol 5 Star Complete Wood Treatment
Available in clear only, Cuprinol 5 Star Complete Wood Treatment is a water-based, low odour and low VOC wood preserver specifically formulated for the treatment of interior timber. Deep penetrating formula ensures long lasting protection against insect attack, re-infestation and fungal decay.
Customer Review – Cuprinol 5 Star Complete Wood Treatment
I ordered this product as I needed to apply a thin coating that got absorbed readily on old interior timbers and new Oak beams alike. Little evidence of any staining which was important. Applied via a spray nozzle and also a brush. Low odour and lasted a long time.
Osmo Wood Protector (4006)
A wood protective treatment that is free from biocides and preservatives. Osmo Wood Protector (4006) is ideal for treating wood in high moisture areas, such as wet rooms, kitchens and bathrooms. Especially suitable for woods that are susceptible to blue stain, such as Pine.
Customer Review – Osmo Wood Protector (4006)
I can only say that I needed an undercoat to protect the bathroom wood door from steam, moisture and similar. So using the Osmo brand made sense before using Osmo oil.
Sadolin Quick Drying Wood Preserver
A clear water-based wood preserver suitable for new and bare timber Sadolin Quick Drying Wood Preserver is perfect as a pre-treatment before applying a wood stain, paint or other wood finish. Provides excellent protection for interior and exterior joinery against wood destroying fungi and blue stain.
Customer Review – Sadolin Quick Drying Wood Preserver
A great product that goes on easily. It’s protecting my log cabin even before I get round to getting the top coat on. Good preparation should result in a long life.
Top wood preserving tip!
All wood, new and old should be treated with a fungicidal wash or multicide wood cleaner before treating with a wood preserver. Why? Wood only needs to get wet or damp once for mould and algae spores to establish themselves in the wood grain. This can happen at any time in the transit or storage of the timber or the finished article including sheds, fences and decking boards. Although wood preservers will help to prevent mould, algae and fungi establishing itself on the wood, they are not always effective at killing off already established spores within the timber.
For this reason, we always recommend that all wood is initially treated with a fungicidal wash or mould and mildew cleaner to kill off any existing spores in the wood grain before applying a preserver.
Want to know even more about wood preservers?
For more information about wood preservers and their uses, contact our team of resident experts who are always on hand to help with project advice and product recommendations. Alternatively, see our wood preserver FAQ page which covers many of the most commonly asked questions about wood preservers.
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