No spin — just the published specs
Standard vs Heavy Duty vs Composite
The same canon of verified numbers our product pages run on, side by side — including the nominal-and-finished sizes most manufacturers won't print.
Cladding
- Standard
- 16mm nominal Tanalised T&G shiplap
- Heavy Duty
- 22mm nominal Tanalised T&G loglap
- Composite
- WPC composite — colour through the board
Why it matters+
Cladding is the building. Thicker boards move less, seal better and shrug off knocks — and the tongue-and-groove profile is what keeps wind-driven rain out of the joints.
Framework
- Standard
- 38×50mm pressure-treated
- Heavy Duty
- 38×50mm pressure-treated
- Composite
- 38×50mm pressure-treated
Why it matters+
The skeleton every panel hangs off. 38×50mm pressure-treated framing is the same on all three builds — we don’t thin the frame to hit a price.
Roof covering
- Standard
- Mineral felt (EPDM upgrade)
- Heavy Duty
- Mineral felt (EPDM upgrade)
- Composite
- EPDM rubber — included
Why it matters+
Felt is the industry standard and fine for years; one continuous EPDM rubber membrane has no seams to lift and carries a 20-year anti-leak warranty (30 fitted by us).
Breathable membrane
- Standard
- Included
- Heavy Duty
- Included
- Composite
- BBA-certified, included
Why it matters+
The invisible layer most cheap sheds skip to save £10–£30 — it lets moisture out of the walls while keeping wind-driven rain off the frame.
Treatment
- Standard
- Tanalith E pressure treated
- Heavy Duty
- Tanalith E pressure treated
- Composite
- None needed
Why it matters+
Tanalith E vacuum pressure treatment forces preservative deep into the timber cells (UC3-rated) — dip-treated sheds only coat the surface. Composite needs none at all.
Maintenance
- Standard
- Colour treatment every 2–3 yrs
- Heavy Duty
- Colour treatment every 2–3 yrs
- Composite
- Zero
Why it matters+
Timber wants an optional colour refresh every 2–3 years to stay looking sharp. Composite is colour-through — nothing to treat, ever.
Colour fading
- Standard
- Refresh with paint or stain
- Heavy Duty
- Refresh with paint or stain
- Composite
- UV-stabilised — rated within 10% over 10 yrs
Why it matters+
All composite fades a little — quality decides how much. Ours has UV stabilisers mixed through the board and is rated to hold colour within 10% over 10 years; timber you simply repaint whenever you fancy a change.
Warranty
- Standard
- 20 years anti-rot
- Heavy Duty
- 20 years anti-rot
- Composite
- 30 years manufacturer
Why it matters+
The number that tells you what the maker really thinks of the build: 20 years anti-rot on timber, Standard or Heavy Duty, and 30 on composite.
Nominal vs finished — the honest version
Timber is measured before machining — that "sawn" size is the nominal figure. Planing it smooth (and, on cladding, cutting the tongue-and-groove profile) removes a few millimetres, so a 16mm nominal board finishes at around 12mm, and a 24mm nominal floor board finishes at around 18mm.
Every timber manufacturer works this way — but most only quote the bigger nominal number. We publish both, so you can compare buildings on the wood you actually get, not the wood it started as.
Prices depend on size — every size page shows all three builds priced live, and Heavy Duty re-prices instantly in the Build studio.
