Why use a shed preservative?
Buying a garden shed is a big investment and it makes sense to spend some time protecting the wood with a shed preserver. After-all, its going to have to withstand the hottest and driest of summers and the wettest and coldest of winters for as many years as possible.
Applying a wood preservative to a garden shed helps to protect the timber against mould, algae and insect attack. In addition, many wood preservers also contain a small amount of wax which offers some limited protection against weathering including wind, rain and sun.
To seal the shed preserver in to the wood grain and provide the shed the best possible protection, it’s always recommended that once applied, any preservative is over-coated with a suitable top-coat such as an exterior wood oil, paint for sheds, shed stain or shed varnish. This will help to ensure that your shed will last year after year and potentially for decades if well maintained.
Types of shed preserver
Wood preservatives come in many guises but essentially, they all do the same job. Even those that are marketed specifically for sheds and fences are just the same as those that aren’t. Most brands produce both clear and coloured versions in either solvent-based or water-based formulas. Some types contain a small amount of wax whilst others do not.
Solvent-based vs water-based shed preservers
A question often asked is ‘are water or solvent-based shed preservatives best?’ Truth is that both types contain the same key preserving ingredients. Although solvent-based wood preservers tend to have better penetration, water-based preservers are more user and environmentally friendly. Both can be overcoated with an exterior wood oil or log cabin treatment to seal in the preservative and protect the structure from the effects of weathering.
What is the best wood preservative for sheds?
So which is the best wood preservative for sheds? This largely depends on what type of look or finish is required. To keep the shed looking natural, use a clear wood preservative and overcoat with a clear exterior wood oil or decking oil for the best protection. Sheds can be easily stained or coloured by using a coloured wood preservative then over-coated with a clear wood oil or clear decking oil. Alternatively, a clear preservative can be used then a coloured decking oil or coloured wood oil can be applied.
If using a water-based shed paint or garden paint, take care to ensure that any wood preservative used does not contain wax, silicon or oil as these will potentially repel the paint from the surface of the shed and prevent adhesion with the wood.
Top 5 Clear Shed Preservers
- Cuprinol Wood Preserver – Clear 5Ltr: Ideal for garden sheds, Cuprinol Wood Preserver Clear is a general-purpose preserver that provides deep penetrating protection to sound wood against decay, mould and blue-staining fungi
- Ronseal Total Wood Preserver – Clear: Ronseal Total Wood Preserver is a general purpose preserver that has been specially formulated to kill woodworm and prevent rot and decay. It is ideal for exterior wood including garden sheds and fences, and is suitable for overpainting. Perfect for use on rough or smooth timber
- Nourish & Protect Premier Wood Preserver by Barrettine: A solvent-based, high-performance exterior wood preserver suitable for garden sheds and fences. Low odour oil/spirit wood preservative that dries to a semi-transparent, matt/satin finish. Provides long lasting protection against wood destroying fungi (wet Rot), wood discoloring fungi and wood boring insects
- Sikagard Clear Wood Preserver – 5 Litre: Provides long lasting protection from wet rot, dry rot, decay and fungi. This fast-drying, non-flammable preserver can be applied to all rough-sawn or planed wood and joinery in damp or wet conditions without loss of performance. Its low-odour, solvent-free formula contains finely dispersed fungicides and algaecides to provide improved penetration into the wood, compared to standard, solvent-based, wood preservers
- Roxil Wood Preserver Clear – 5Ltr: A solvent-free, deep penetrating, liquid wood preservative that defends exterior wood against dry rot, wet rot, fungal attack and woodworm infestation. Ideal for wooden fences, decking, sheds, garden furniture and more. Its clear, Odourless formula – Increases the lifetime of timber by preventing wood destroying, wood discolouring fungi and woodworm. HSE Approved. Tested to European standards EN 152, 113 and 46-1. Designed to be used as a pre-treatment before application of Roxil Wood Protection Cream.
Top Coloured Shed Preservers
- Ronseal Shed and Fence Preserver: A coloured shed & fence preservative that colours, preserves and nourishes shed and fence timbers
- Cuprinol Shed and Fence Protector: A coloured, protective wood treatment for garden sheds and fences
Other ways to colour, waterproof, and protect sheds
An alternative approach to colouring or staining a shed with a wood preservative is to use a clear wood preserver first, and then a shed and fence stain, an oil-based, coloured shed treatment, or an exterior paint for sheds. These types of shed treatments are generally available in a much wider range of colour options.
Those of a certain age will remember when anything wood in the garden used to be treated with Creosote. The sale of Creosote is now regulated and can only be sold to farmers and for other industrial uses.
The good news is that there is a safer, more environmentally friendly version called ‘Creocote’. This oil based Creosote substitute is perfect for use on garden sheds and fences and is available in light and dark shades of brown.
- Barrettine Creocote: An oil-based Creosote substitute for exterior woods
Other shed treatments
Although wood preservatives are essential for protecting shed timbers from biological threats such as mould, algae and insect attack, for the best long term protection, it is recommended that sheds are first preserved then treated with a top-coat such as an exterior wood oil like Barrettine Log Cabin Treatment or even a clear decking oil. Applying a wood oil over the preservative extends the effective life of the wood preservative and provides excellent weather protection. The oil also keeps the shed timbers nourished and supple, therefore helping to prevent cracking, splitting and warping over time. To maintain the finish, simply reapply a fresh coat of wood oil as and when required to maintain the sheds weather resistance and appearance.
If coating the shed with a water-based stain, paint, oil, or other shed treatment, it is important to ensure that the preservative is one that doesn’t contain wax as this will repel the top-coat and prevent it from adhering to the shed.
Applying a shed preserver
When applying a garden shed preservative it’s worth remembering that both solvent and water-based preservers contain fungicides and biocides to protect sheds, log cabins, and garden offices from biological growth such as mould, algae, lichens and insect attack. For this reason it is strongly advised to always wear a suitable mask, old clothes, protective gloves, and eye protection and always follow the manufacturers instructions on the tin.
Top tips before applying a shed preservative
If mould, algae or fungi is already present on the shed surface, it must first be treated with a suitable mould and algae cleaner or fungicidal wash, and before applying a wood preservative. Preservers are designed to help prevent biological growth but will not kill it if it is already established. If mould, algae or lichens are already present on the wood, use a suitable shed cleaner to remove mould, algae and lichens.
Although wood preservers are safe for man, plants and animals when fully dry, they are very harmful to aquatic systems and should be kept well away from garden ponds, streams, drains and other water courses. Pets and children should be kept away from the liquid and freshly treated sheds until they are dry.
Always cover and protect items and areas not to be treated, especially stone, concrete, plastic surfaces and plants, and especially if applying a coloured preserver. Coloured wood preservers will easily stain these surfaces and could ruin some types of plastic.
Sealing in a shed preservative
Although many (not all) wood preservatives contain a small amount of wax, they don’t always provide long term weather protection. To seal in the wood preserver and provide the best all-round wood protection, garden sheds treated with a shed preservative can usually be treated with an exterior wood oil, suitable for garden sheds, once the preserver has fully dried, usually after 72 hours. This will help to keep shed timbers supple and nourished whilst protecting against water ingress and weathering. Some external wood oils also contain UV filters that will help to preserve the shed colour for longer.
If the shed is going to be treated with a water-based oil, paint or stain. It is important that the preservative does not contain any wax or silicon. Preservers that contain wax will repel water-based top coats and prevent them from adhering to the wood.
Can shed preservatives be spray applied?
This depends on the type of shed preserver being sprayed and also the immediate surroundings. There are several things to consider when spraying a wooden shed. Firstly, many preservers contain biocides and fungicides to protect sheds from biological growth and insect attack. Breathing in the fine mist when spraying should be avoided. Another factor is over-spray. Coloured shed preservers can and will stain porous surfaces such as stone or paved patios, rockeries, pathways and more, and is very difficult, if not impossible to remove.
Not all wood preservers or stains are suitable for spraying due to their viscosity. Many garden pump sprayers are only suitable for thin liquids like water. There are however a couple of sprayers that are specifically designed for spraying garden shed preservers and stains such as those below.
These machines are often designed to only spray a specific product or group of products from the sprayer manufacturer.
- Ronseal Precision Pump Sprayer: For spraying the Ronseal range of Fence Life and Fence Life Plus treatments
- Cuprinol Spray & Brush Pump 2-in-1 Shed and Fence Paint Sprayer: Designed for spraying the Cuprinol Spray Fence Treatment range.
Alternatively, there are a range of electric sprayers suitable for spraying sheds available but always check that they are compatible with the type of shed preserver or stain that you wish to spray.
Probably the simplest and most common approach approach is to use a block brush. These wide brushes are designed to cover large areas and although painting a large shed can be daunting, with a couple of shed block brushes and some helping hands, the task can get done more quickly.
More information on garden shed care and maintenance
Find further, general information and advice on other garden shed treatments here. Alternatively, you can find out more about specific shed treatments below.
- Before treating any garden shed with a shed preserver, stain, oil or paint, it has to be clean and free of any mould, algae or lichens. Find out which shed cleaner is best to clean and remove these common issues
- Find out about a range of shed paints and colours here. What is a shed paint? The answer isn’t as straight forward as you might think
- An exterior wood oil will protect garden sheds from weathering and keep the wood supple and nourished. With a range of clear and coloured wood oils available, which oil-based shed treatment is best? Our guide will help you decide
- Find out about a range of shed stains and colours here. What is a shed stain? As with paints, shed stains are not as straight forward as you might think. What is the difference between a shed paint and a shed stain?
Garden Shed FAQ’s
Can’t find the answer to your shed care or maintenance project above? See our frequently asked shed questions and answers page, where we try to answer some of the more commonly asked questions relating to shed care, maintenance, and shed treatments.