Building a garden cabin is one of those projects that rewards a bit of thinking before you order a single board. The timber you choose decides how the cabin looks on the day it goes up, how it looks in ten years, and how much of your spring you'll spend sanding and re-oiling. Get it right and the building quietly looks after itself. Get it wrong and you'll be fighting the weather every season.

In the UK, three species dominate: pine, cedar and larch. All three work. They simply ask different things of you.

Why the Species Matters More Than the Colour

Timber for outdoor buildings is judged on two things: natural durability and stability. Durability is how well the wood resists rot and insect attack without help. Stability is how little it moves as it takes on and gives off moisture through the British year.

In the UK, nearly all softwood is graded by a durability class. Class 1 is the most resistant, Class 5 the least. A timber's heartwood is the durable part; sapwood is the soft, sugary outer layer that rots quickly unless it has been pressure-treated. This is why two cabins built from the "same" wood can behave completely differently if one uses heartwood cladding and the other uses sapwood.

Whichever species you pick, insist on heartwood for anything exposed, and check the moisture content before fitting. Cladding that is too wet when it goes on will shrink and open up gaps at the joints.

Pine: The Practical Workhorse

Pine is the default for a reason. It is widely available, comparatively cheap, easy to saw and screw, and it takes paint and stain beautifully. Most garden buildings you see on a garden centre forecourt are pine, usually Scandinavian or Baltic, and usually pressure-treated to compensate for its low natural durability.

Used well, pine is a sensible choice. It is stable when it is properly dried, it holds a sharp edge, and it is forgiving of the small mistakes that any self-build involves. The trade-off is upkeep. Untreated pine sapwood will discolour and start to decay within a couple of seasons in damp conditions. Even treated pine benefits from a protective finish, refreshed every year or two.

Pine suits:

• Framing, studs, floor joists and internal linings, where it is sheltered and cheap
• Cabins that will be painted rather than left natural
• Budget-conscious builds where you would rather spend on insulation and glazing
• Shiplap or tongue-and-groove cladding that will be treated and maintained

If you go with pine cladding, buy pressure-treated boards, seal every cut end with end-grain preservative, and plan on a coat of oil or stain within the first few months.

Cedar: The Low-Maintenance Option

Western red cedar is the timber people choose when they want the cabin to look after itself. Its heartwood sits in durability Class 2 and contains natural oils that repel moisture and discourage insects, so it can be left bare without treatment and still perform for decades. It is also remarkably stable, which means less movement, tighter joints and fewer draughts.

Visually, cedar is hard to beat. Freshly installed it is a warm, honey-red; left alone it weathers to a soft silver-grey that suits a garden far better than you might expect. It also takes a stain well if you want to hold the colour.

The catch is cost. Cedar typically commands a significant premium over pine, and supplies can be variable. It is also softer than many people assume, so it dents and marks more readily under a ladder or a stray football.

Cedar earns its place on:

• Visible cladding, fascias and door surrounds where appearance matters
• Roofs and anything regularly soaked, where rot resistance pays off
• Builds where the owner wants minimal maintenance for years at a time

Bear in mind that "cedar" sold in the UK is not always Western red cedar. Check the species before you compare prices.

Larch: The Middle Ground

Larch is the quiet favourite of people who have built before. It sits between pine and cedar on both cost and durability, with heartwood around Class 3 to 4, meaning it will last well if it is kept dry and reasonably well ventilated, but it wants some protection.

Its great strength is density. Larch is harder and heavier than pine, so it resists knocks and takes fixings firmly. It has a lovely straight grain, and Siberian larch in particular is prized for tight growth rings and a clean, pale appearance. Left untreated, it fades to a grey not unlike cedar, though the process is quicker and less even.

Larch works well for cladding, decking and structural elements that will be stained or oiled. It is less suited to being left entirely bare in a shaded, damp corner, where it will soak up moisture and start to go soft. Budget for a finish every two to three years.

Matching Timber to the Job

The mistake most builders make is picking one species for the whole cabin. A smarter approach is to mix them.

Use pressure-treated pine for the frame, floor and roof structure, where nobody will see it and the loads are high. Use cedar or larch for the cladding, doors, windows and any trim on show. Treat the base and any timber within 150mm of the ground as sacrificial — use a damp-proof course, keep timber clear of soil, and accept that these boards will need replacing first.

Whatever you choose, three habits will add years to the build:

• Keep a 300mm gap between the cabin base and the ground, with airflow underneath
• Seal every cut, knot and end grain as you go, not at the end of the project
• Re-coat before the old finish fails, not after the grey sets in

Buy the best timber you can afford for the parts you see and touch, and be pragmatic about the parts you don't. That balance is what separates a cabin that still looks well after fifteen winters from one that needs re-cladding in five.