Using a wood preserver helps to protect and preserve decking timbers, posts and supports from mould, algae, fungi, wood rot and insect attack, all of which can degrade untreated wood over time.
Types of Wood Preservative
Wood preserver come in water-based and solvent-based formulas and are usually available in both clear and coloured variations. Solvent-based wood preservatives generally penetrate deeper into the timber and often dry quicker than water-based formulas. Water-based preservatives are far less smelly to work with and are less harmful to the environment.
Although solvent-based formulas have traditionally been used for exterior wood care, stricter legislation regarding high VOC’s (Volatile Organic Compounds) means that many solvent-based wood preservers are being phased out and replaced with water-based versions.
Using a clear wood preserver on decking will retain the natural look of the wood whereas a coloured preservative will stain the wood, effectively acting as a decking stain. Although wood preservatives will protect decking from biological threats such as mould, algae and wood rot, they are not sufficient or durable enough to use as a standalone decking treatment. For this reason, once preserved, decked areas must be treated with a suitable decking oil, decking stain or decking paint.
Recommended wood preservatives for decking
Before buying a wood preservative to treat decking, it’s important to know what sort of decking treatment or finish you’ll be using. Some wood preservatives contain a small amount of wax to provide a degree of weather protection. Whilst this isn’t an issue with most solvent-based decking oils, it can be a problem with water-based decking paints and stains as the wax will repel the finish and prevent it from adhering or bonding with the surface of the deck. This can result in the flaking or peeling of the decking finish.
Top 3 wax-free wood preservers for decking
Recommended for use with water-based and solvent-based decking paints, decking stains and decking oils.
- Barrettine Premier Universal Preserver: A clear, wax-free, solvent-based, exterior wood preserver perfect for wooden decking and other exterior wood to prevent wood boring insects, wood rotting fungi and blue stain
- Sadolin Quick Drying Wood Preserver: A clear, water-based, wax-free wood preserver for new and bare timber. Perfect as a pre-treatment before applying a decking stain, paint or oil. Provides excellent protection against wood destroying fungi and blue stain
- Cuprinol Wood Preserver Clear: A clear, water-based, wax-free wood preservative treatment for interior and exterior timber that prevents insect attack, rot and decay
Wood preservers that contain wax
Can be used with solvent-based decking oils but not recommended for products that coat the decking such as decking stains or paints.
- Barrettine Premier Wood Preservative: A solvent-based high-performance exterior wood preserver suitable for garden decking. available in clear and coloured
- Ronseal Total Wood Preservative: A highly penetrative, solvent-based wood preserver for exterior timbers including decking. The clear formula is wax-free whilst the coloured versions contain wax
How to preserve wooden decking
For the best protection preserve all or as many of the timber components as possible with two coats of wood preservative. This should include both sides, edges and especially the end grain or sawn ends of the timber. The same should then be done with a suitable clear or coloured decking oil or decking stain or decking paint after the preservative has fully dried. This will help to protect these areas and especially sawn ends from moisture and water ingress.
Choosing the right decking preserver
If planning on painting or using a varnish type decking stain, its worth remembering that some decking preservers contain wax. Although this is fine if over-coating with a solvent-based decking oil, the wax content will prevent water-based decking oils, paints and varnish type stains from adhering to the wood. This could result in the finish flaking off.
Not sure what you need to clean, maintain or restore your garden decking? Read our decking care, maintenance and treatment guide to find out what you need to restore your wooden decking.