What Timber Is Best for Sheds? Shed Timber Sizes and Thickness Explained

"Shed timber" covers several different parts: the frame that holds the building up, the cladding on the outside, the floor, the roof boards and the base underneath. This guide explains what to look for in each, with real figures from the ranges we sell so you can compare like with like. For the bigger picture on choosing a shed, see our best garden sheds guide.

Which wood are sheds made from?

Almost all timber sheds are made from softwood, usually spruce (sometimes sold as whitewood) or pine (often called redwood). Power Sheds, for example, use Scandinavian timber, and the Power Sheds Premium range uses pressure-treated Scandinavian pine. Hardwood is rarely used for sheds because of its cost and weight. With softwood, the species matters far less than the treatment and the thickness.

Treatment: the biggest difference

Whatever the treatment, a timber shed lasts longer if it's re-treated regularly. Our timber care guide explains how often, and we sell Protek Shed & Fence and Protek Wood Preserver Plus Plus.

Shed frame timber sizes

The frame is the skeleton of the shed. A thicker frame keeps the building rigid, holds shelving better and stops doors dropping over time. These are the frame sizes on the sheds we sell:

Frames are measured differently from brand to brand, and some figures are nominal (before planing), so treat small differences with caution. The big steps, such as a standard frame against a heavy-duty one, are what matter.

Cladding thickness

Cladding is the boarding on the walls. Thicker boards make a stiffer, more weather-resistant wall.

• 12mm tongue and groove is the common standard: Power Sheds, Sovereign and Shedlands standard cladding.
• 15mm to 16mm: Sovereign 15mm loglap and 15mm pressure-treated upgrades, Shedlands 15mm loglap, and Suresheds' 16mm option.
• 18mm to 20mm: Sovereign and Shedlands Premier 18mm shiplap, Vista 18mm pressure-treated boards and Suresheds' 20mm option.

Nominal vs finished: a board's nominal size is before it's planed; the finished size is what you get. Sovereign's standard cladding is sawn at 16mm and planed to 12mm, and Shedlands Premier is 22mm nominal and 18mm finished. Check both sheds are quoted the same way before comparing.

Heavy-duty sheds: what timber thickness to look for

If you're building a workshop, storing heavy machinery or fitting benches, step up on every part:

• Frame: around 44x44mm or more, such as the Sovereign Cumbria (44x44mm), Shedlands Heavy Duty (50x50mm with diagonal cross bracing), Power Premium (58x44mm) or Suresheds Wharfedale Workshop (3x2 inch, up to 24x12ft).
• Cladding: 16mm to 20mm, or an 18mm Premier upgrade.
• Floor: the floor takes the most punishment. Upgrades include the Shedlands Heavy Duty 22mm Floor Boards and the Sovereign Pressure Treated Heavy Duty Floor (18mm).
• Roof: a heavy-duty felt, felt tile or EPDM rubber roof covering lasts longer than standard felt.

Timber for the floor and roof

• Floor: Power Sheds and Sovereign sheds use 12mm tongue and groove floors, Shedlands use 22mm floorboards, and Power Sheds 44mm log cabins have a 19mm floor. Heavier floors are worth it if you'll be wheeling a mower or standing at a bench.
• Roof boards: Power Sheds and Sovereign use 12mm tongue and groove roof boards, which are sturdier than thin sheet material. The felt or rubber covering on top keeps the rain out.

Timber for a shed base

Timber that touches the ground needs the most protection. Use pressure-treated timber rated for ground contact, never untreated softwood.

• The Power Sheds Shed Base Kit uses UC4 pressure-treated timber, rated for direct ground contact, and can go on soil, grass, paving or hard standing.
• The Suresheds Tanalised Airflow Base is made from 4x2 tanalised timber and fitted with your Suresheds building.
• The Shedlands Timber Shed Base is a pressure-treated frame that lifts the floor bearers clear of the ground.

The bearers under the floor should also be pressure-treated. Our base guide explains bearers, spacing and every type of base.

Common questions

What timber is best for sheds?

Most sheds are built from softwood such as spruce or pine, and both make good shed timber. What matters more is how the timber is treated and how thick it is. Pressure-treated (tanalised) timber lasts longest and usually carries a longer guarantee. Dip-treated or base-coated timber costs less but needs re-treating when it goes up and then every year.

What thickness of timber should be used for a heavy-duty shed?

Look at the frame as well as the cladding. The heavier-duty sheds we sell use frames of around 44x44mm to 3x2 inches, such as the Sovereign Cumbria (44x44mm), Shedlands Heavy Duty (50x50mm), Power Sheds Premium (58x44mm) and Suresheds Wharfedale Workshop (3x2 inch). For the walls, 16mm to 20mm cladding is a step up from the common 12mm, and an 18mm to 22mm floor copes better with heavy kit.

What size timber is used for a shed frame?

It varies by range. On the sheds we sell, standard frames run from 32x44mm (Sovereign) and 38x50mm nominal (Shedlands) to 44x28mm, doubled in key areas (Power Sheds), and 2x2 inch (Suresheds). Heavier-duty buildings go up to 50x50mm, 58x44mm and 3x2 inch.

What timber should I use for a shed base?

Use pressure-treated timber rated for ground contact for anything that touches soil or gravel. The Power Sheds Shed Base Kit uses UC4 pressure-treated timber, which is rated for direct ground contact, and the Suresheds Tanalised Airflow Base is made from 4x2 tanalised timber. Ordinary untreated softwood will rot quickly on the ground.

What timber is best for a shed roof?

Tongue and groove roof boards make a sturdier roof than thin sheet material. Power Sheds and Sovereign sheds use 12mm tongue and groove roof boards under the roof covering. The covering on top, whether felt, felt tiles or EPDM rubber, is what keeps the rain out, so check its condition every autumn.

Is tanalised timber better for a shed?

Tanalised means pressure-treated: the preservative is forced deep into the wood rather than coating the surface. It gives longer-lasting protection against rot and insects and usually comes with a longer guarantee. Suresheds and the Power Sheds Premium range are fully pressure-treated, and Sovereign and Shedlands offer pressure-treated cladding upgrades.

Specifications vary by model and size, so always check the product page. Guarantee terms are the manufacturers' own.