Choosing timber for your garden should be easy, but somehow it isn’t. Go into any timber yard, and you’re faced with like twenty types of wood, all vaguely resembling one another. The bloke there takes it for granted that you’re on the ball. You don’t. So you find yourself shopping and hoping for the best, buying whatever’s on sale. Then six months out, your nice new deck has warped into the shape of a Pringle, and you don’t know what happened. We’ll tell you what went wrong. You picked the wrong wood.
British weather is brutal on timber. Rain, sun, frost, more rain. Wood that looks fine indoors can be a sodden disaster outside in just a year if you get this wrong.
Why Your Timber Choice Matters More Than You Think
Garden timber sits outside getting hammered by the weather constantly. It swells when wet, shrinks when dry, then swells again. Insects show up looking for food. Fungi move in whenever there’s moisture. Wrong timber means your project fails. Simple as that.
Raised beds made from cheap softwood turn to mush in two years. Fences fall apart. Decking warps so badly you can’t walk on it barefoot. Yeah, you saved fifteen quid at the time. Now you’re rebuilding everything.
The right timber lasts decades. Wrong timber costs you twice because you’re doing it again.
Understanding Wood Durability Classes
British standards rate timber in five durability classes. This isn’t boring technical stuff. It tells you how long your wood lasts outside.
- Class 1: Very durable, lasts 25+ years
- Class 2: Durable, 15 to 25 years
- Class 3: Moderately durable, 10 to 15 years
- Class 4: Slightly durable, 5 to 10 years
- Class 5: Not durable, won’t see 5 years
Anything touching soil needs Class 1 or 2. Decking can get away with Class 2 or 3 if it’s treated. Fence posts in the ground? Class 1 minimum, or you’re wasting your time.
The Best Timber Types for Different Garden Projects (And Why They Work)
Oak
European oak is brilliant for outdoor use. Class 2 durability means British weather doesn’t faze it. Strong, gorgeous colour, ages beautifully. There’s a reason old barns and ships were made from oak. It doesn’t quit.
Costs proper money, though. But you get what you pay for. Oak outlasts basically everything else.
Best for: Pergolas, garden furniture, anything permanent.
Douglas Fir
Canadian Douglas fir has gotten really popular in the UK. Class 3 durability when treated. A wild grain pattern looks interesting instead of boring. Machines easily if you’re DIYing.
Cheaper than oak but still performs well. The Natural History Museum used UK-grown Douglas fir for their garden structures in 2025. Works for them, works for you.
Best for: Decking, raised beds, outdoor furniture.
Cedar
Western red cedar resists rot and insects naturally. Class 2 durability without any treatment. That’s massive. It weathers to silver-grey, or you can oil it to keep the red tone.
Lightweight makes it easy to handle. Smells amazing when you cut it too.
Best for: Cladding, fencing, storage boxes.
Larch
European larch is affordable and available everywhere in the UK. Class 3 to 4 durability, but treat it properly, and it does the job nicely.
Warm honey colour when fresh, which darkens over time. Good strength.
Best for: Fencing, cladding, garden edging, and budget projects.
Scandinavian Spruce
Spruce is in every timber yard. Light, easy to work with, uniform. Class 4 durability means it needs treatment for outdoor use, but once protected, it’s fine.
Cheapest option by miles. If your timber isn’t touching the ground and you’ll maintain it, spruce works.
Best for: Sheds, summer houses, and structures with roofs.
Teak
Class 1 durability. Waterproof, stable, gorgeous. Used for boats because it handles water better than anything.
Stupidly expensive, though. Only worth it for high-end furniture.
Best for: Premium furniture, statement pieces, when money doesn’t matter.
Treated vs Untreated Timber: What You Need to Know
Pressure-treated timber has preservatives forced into the wood fibres. This extends softwood life massively. Pine or spruce would rot quickly outside without it.
Treated timber usually comes with 15- to 25-year guarantees against rot. That’s proper reassurance for structural stuff.
Treatment gives wood a green or brown tint. Not everyone loves it, but it fades. You can paint over it once it dries out.
Here’s the thing. Freshly treated timber is soaking wet from the process. Let it dry for a few weeks before painting or staining. Otherwise, nothing sticks, and you’re redoing it.
Hardwoods like oak and cedar don’t need treatment because they’re naturally durable. But extra protection doesn’t hurt.
Sustainability Stuff
Around 40% of UK timber is now from sustainable sources. Search for FSC or PEFC certified. These are signals for responsibly managed forests.
UK-grown timber is having a moment. Douglas fir, oak, and larch all grow commercially here. Buying local cuts transport emissions and supports British forestry. The 2025 Wood Awards featured projects using UK-grown wood.
Reclaimed timber works brilliantly too. Old scaffold boards, fence panels, or demolition timber make great rustic features. Places like Oxford Wood Recycling clean it up and sell it cheaply.
Matching Timber to Your Specific Project
- Raised Beds: Oak, cedar, or treated softwood. Soil contact needs durability. Larch, if you’re watching money. Line the inside with plastic for extra life.
- Decking: Douglas fir or treated softwood. Oak if the budget allows. Leave gaps between boards for drainage.
- Fencing: Treated softwood panels are standard because they’re affordable and will last 15 years minimum. For a nicer look, use cedar or larch.
- Garden Furniture: Oak, cedar, or teak, depending on budget. These handle being outside year-round. Treated pine works if you cover it in winter.
- Pergolas: Oak or Douglas fir. Need strength plus durability. Design around available sizes rather than forcing weird dimensions.
- Sheds: Treated softwood or cedar cladding on treated frames. The base needs to be off the ground.
Practical Tips
Measure twice, buy once. Timber yards hate returns. Know your dimensions before shopping.
Check the moisture content if possible. Too wet means shrinking and warping later. Around 18% is ideal for outdoor use.
Buy 10% more than needed. You’ll make cutting mistakes or find bad knots. Extra wood saves a second trip.
Store timber flat, off the ground, and covered on top with air circulation underneath. Twisted wood is impossible to work with.
Apply the finish to all sides. Water gets in anywhere. The board ends especially soak up moisture like a sponge.
Where to Actually Buy Your Timber
Builders’ merchants stock basics. Specialist timber yards have better quality and selection. Check out Timber Store for a proper range of treated and natural timbers.
Online ordering works fine now. Most places deliver. Just factor in lead times.
Reclamation yards are worth visiting for character pieces. You might find old oak beams or weathered planks perfect for rustic projects.
Common Mistakes
- Using untreated softwood outside. Don’t. It rots within two years.
- Not accounting for wood movement. Timber expands and contracts with moisture and temperature. Leave gaps or use appropriate fixings.
- Overcomplicating things. Simple designs with standard sizes cost less and go together more easily.
- Skipping prep work. Sand down any rough edges, splinters, and prime as necessary. It takes an hour, but it makes everything better.
- Buying the cheapest without thinking. If you’ve to replace it in three years, it’s a false economy.
Look
The right timber for the right job isn’t complicated once you know the basics. Hardwoods like oak and cedar cost more but last ages. Softwoods like Douglas fir or treated spruce work brilliantly for most projects at lower prices.
Match the durability class to your project. Factor in British weather. Don’t skimp on ground contact stuff.
If you’re spending a weekend building something, use timber that’ll still be there in ten years. Your future self will thank you.
Now go build something decent.
