Best Wood Preservative for Cedar: 2025 Expert Review
DR Joinery
Expert Joiner & Timber Specialist
Western Red Cedar is the gold standard for garden studios and summerhouses due to its natural resistance to rot and decay. However, a common misconception amongst homeowners is that 'rot-resistant' means 'indestructible'. Without the right care, that beautiful reddish-brown hue will quickly turn a patchy silver-grey.
Living and working in York, I see firsthand what our wet winters do to external timber. Even high-quality cedar cladding can suffer from surface mould and algae build-up if not properly treated with a preservative before the final finish is applied.
In this review, I am looking at three wood preservatives that act as the perfect foundation for protecting your cedar outbuildings. Whether you are treating a brand new installation or restoring an older summerhouse, these products provide the essential chemical defence needed before oiling or staining.
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Specs vs. The Real World
The Spec: "Clear Protection"
"A clear preservative will keep the wood looking brand new and stop it changing colour indefinitely."
Clear preservatives stop rot and fungi, but they offer zero UV protection. The sun will still bleach the cedar grey unless you follow up with a UV-protective oil or stain.
The Spec: "One Coat Application"
"Slap it on quickly and the job is done for years."
On rough-sawn cedar, you need to saturate the grain. A single thin coat rarely penetrates deep enough. I always recommend two generous coats, especially on end-grains where water wicks in.
My Top 3 Recommendations
Three options to cover different needs and budgets
Everbuild Wood Preserver – Interior And Exterior Use – 1 Litre
Everbuild
If you are patching up a specific area of a cedar summerhouse or treating a small joinery project, this 1-litre tin is the ideal entry point. It utilises micro-fine active technology to penetrate deeply into the grain, offering robust protection against wet and dry rot.
The Good
- Excellent price point for small jobs
- Low odour compared to traditional solvents
- Deep penetration thanks to micro-fine technology
The Bad
- 1 Litre doesn't go far on cladding
- Requires overpainting/varnishing for UV protection
Installer Tip:
Use this size for treating cut stability ends during installation. Whenever you cross-cut a piece of cedar cladding, dip the end in this tin before fixing it to the wall to prevent water ingress at the joints.
Priced at £8.24 at the time of writing
Check Price on AmazonEverbuild Wood Preserver – Interior And Exterior Use – 5 Litres
Everbuild
For a full garden studio or summerhouse, buying in bulk is the only sensible option. This 5-litre tin offers the same high-quality protection as the smaller version but at a much better price per litre. It is the professional choice for treating large surface areas of cedar cladding efficiently.
The Good
- Best economic value for large projects
- Sufficient quantity for a standard garden shed/studio
- protects against blue stain and wet rot
The Bad
- Heavy tin to handle whilst up a ladder
- Still requires a UV topcoat for aesthetics
Installer Tip:
Pour a workable amount into a paint kettle rather than working directly from the 5L tin. It is safer, lighter, and prevents you from contaminating the whole tin with sawdust from your brush.
Priced at £19.98 at the time of writing
Check Price on AmazonCuprinol 5330417 Wood Preserver - Clear - 1L
Cuprinol
Cuprinol is a trusted name in UK timber preservation. This water-based formula is particularly good if you plan to paint or stain your cedar shortly after treatment. It acts as an excellent primer/basecoat that actively prevents rot without the potent smell associated with traditional solvent preservers.
The Good
- Low odour makes it pleasant to use
- Brushes clean up with water (no white spirit needed)
- Excellent compatibility with topcoats
The Bad
- More expensive per litre than the bulk Everbuild option
- Water raised grain may require light sanding before topcoat
Installer Tip:
Because this is water-based, it may slightly raise the grain of the cedar. Once dry, run a very fine sandpaper (180 grit or higher) lightly over the surface before applying your oil or stain for a furniture-grade finish.
Priced at £12.40 at the time of writing
Check Price on AmazonFrequently Asked Questions
Why does cedar turn grey?
Can I use these preservatives on the inside of a summerhouse?
How often should I treat my cedar garden studio?
Is pressure-treated timber better than cedar?
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