Metal vs wooden vs plastic sheds: which lasts in a UK garden?
A pressure-treated timber shed suffers less from condensation, a galvanised steel shed is the most secure but needs venting, and a plastic shed needs almost no upkeep. The guarantee and the base matter as much as the material.
The short answer
Choose wood (pressure-treated shiplap or tongue and groove; we suggest going thicker than the standard 7–11mm cladding) if you want a shed where condensation is usually not a problem. Choose galvanised steel for bikes and expensive kit, but plan for venting and anchoring. Choose plastic for no-paint, low-upkeep storage on a sheltered, solid base. Compare guarantees: they range from 10 to 25 years.
Metal, wooden and plastic sheds compared
| Wooden | Metal (galvanised steel) | Plastic (resin or HDPE) | |
|---|---|---|---|
| Example guarantees | 10 years anti-rot (dip treated, if re-treated every year); 25 years (pressure treated) | 10, 12 or 20 years, depending on maker | 10 or 15 years |
| Upkeep | Re-coat every 1–2 years; every year for dip treated | Minimal: a simple wash with soap and water | Almost none |
| Condensation | Usually not a problem, according to Summerhouse24 | The main complaint; needs vents and a dry base | Can happen: plastic doesn't breathe |
| Security | Generally lower | Highest, especially on certified models | Hard to secure |
| Floor | Varies by model | Varies (Asgard includes one; the Yardmaster listed has none) | Included on Keter and Lifetime models |
| Fixing down | Sits on a level base or bearers | Bolt down (anchor kit often included) | Light, must be anchored through the floor |
The rest of this guide explains what sits behind each row, starting with the thing most comparisons skip: how much wooden sheds vary.
Wooden sheds: cladding and treatment decide how long they last
"Wooden shed" covers everything from a thin budget box to a solid building. Two details on the spec sheet tell you which you are looking at.
Cladding. Overlap boards sit horizontally, each one lapped over the one below. It is the cheapest style and is typically around 7mm thick. Shiplap boards slot together with the lower edge sitting over the board below. Tongue and groove boards slot together into a flat, tight wall, usually 11–15mm on panel sheds. Standard shed cladding is about 7–11mm; upgraded ranges go to 19mm, 28mm or 44mm.
Treatment. Dip-treated timber is dipped in preservative that soaks into the outer layer. Garden Buildings Direct says this protects the wood for about 12 months, after which it needs a new coat, and annual re-treatment is usually a condition of the guarantee. For example, a Forest 6x4ft overlap dip-treated shed (7mm cladding) carries a 10-year anti-rot guarantee "provided product is re-treated annually". Pressure-treated timber has preservative forced into it under pressure in a sealed cylinder, which goes deeper. Forest's Beckwood 6x4ft shiplap shed (12mm cladding, pressure treated) is guaranteed against rot for 25 years.
The timber species matters too. Which? notes that most sheds are pine or spruce, that larch and Douglas fir are slightly more rot resistant, and that cedar is the most rot resistant but costs almost twice as much as pine.
Summerhouse24 adds that wood breathes and absorbs changes in moisture, so condensation is usually not a problem.
Metal sheds: secure, but plan for condensation
Most metal sheds are galvanised steel: steel coated in zinc against rust. Better ones add a paint or enamel coat on top. Screwfix lists Yardmaster's 7ft6 x 6ft apex metal shed as hot-dipped galvanised steel with a 12-year manufacturer's guarantee (T&Cs apply). Asgard offers 10 years on its weatherproof metal storage. Biohort's galvanised, enamel-coated sheds come with a 20-year guarantee against corrosion. Asgard says a well-maintained metal shed can last upwards of 20 years. Which? warns that thin, cheap panels are flimsy, and that higher-quality sheds are stronger, more secure and less prone to rust.
Condensation is the complaint you will see most in forum threads. Steel is cold, so warm, damp air inside the shed condenses on the roof and drips onto whatever is below. Owners on Mumsnet and Singletrack describe exactly this, while Singletrack owners of vented metal sheds (an Asgard among them) report no problems. Moisture comes from the base, from wet bikes and mowers, and from poor airflow. The fixes, from Asgard, Gardensite and Norfolk Sheds:
- Choose a shed with roof vents, and leave space around it for air to move; keep it away from walls, trees and shrubs.
- Lay a damp-proof membrane under a concrete base and let the concrete cure fully (over a week in damp weather) before building on it.
- Seal along the inside of the base rails with silicone once the shed is bolted down.
- Let wet tools, bikes and mowers dry before you shut them in.
- If it still drips, line the underside of the roof with insulation or fit a raised timber floor on bearers.
Security is where metal earns its place. Asgard's high-security sheds are approved under the police Secured by Design scheme and tested by the Loss Prevention Certification Board (LPCB). Cheap metal sheds are a different matter: one Singletrack poster called metal sheds "very insecure"; another replied that this applied to Yardmaster "tin cans", and that an Asgard is considerably more secure.
Floors, assembly and anchoring. Many metal sheds come without a floor (the Yardmaster listing says "Base Not Included"; Asgard's have an integral metal floor), so you need a solid, level base. Asgard asks for one at least 50mm thick. Assembly is fiddly: one Mumsnet poster said a 10x8ft metal shed "took absolutely ages", and Biohort recommends teams of two or three. Bolt it down: Biohort rates its sheds to 150km/h winds only when professionally assembled and anchored. Which? also notes metal sheds heat up quickly in sun, which makes them a poor workshop or office.
Plastic sheds: no painting, but anchor them well
Plastic sheds are made from polypropylene resin (Keter) or HDPE panels on a powder-coated steel frame (Lifetime). Gardensite describes Keter's resin as UV resistant, and Keter says it lasts "many years without warping, rusting, fading or peeling". Gardensite describes Lifetime's UV-protected plastic as resisting "cracking, fading, rust, and rot". Keter gives a 15-year limited warranty if you register the shed; Lifetime gives 10 years. Most include a floor: Keter's sheds come with a heavy-duty floor panel, and Lifetime's with a PVC floor. Lifetime puts assembly at about 2–6 hours for two adults.
The drawbacks are wind and security. Plastic sheds are light, so they must be fixed through the floor into a solid base; Which? calls them flimsy in stormy weather and hard to secure. Like metal, plastic doesn't breathe, so condensation can form inside. Summerhouse24 advises against storing rust-prone metal, seeds, electronics or anything that must stay dry in a plastic shed; for metal sheds it says you need electrical ventilation if you store metal, electronics or textiles. Upkeep is minimal: a Singletrack poster reported a Keter still in good condition after about ten years with no maintenance.
What it costs
Based on the examples in this guide, a small (6x4ft to 7ft6 x 6ft) pressure-treated shiplap shed or galvanised steel shed cost about £400–£500 at UK retailers in October 2026. Premium coated-steel ranges cost much more: Biohort's Europa range started from about £890 in October 2026. Large plastic sheds are not always the cheap option either: a Lifetime 10x8ft cost about £2,200 in October 2026. Remember to add the base, which most metal sheds and all sheds on grass need.
Size it for what you store
Norfolk Sheds suggests 6x4ft or 7x5ft with double doors for two adult bikes and tools, and 8x6ft once you add a mower and barbecue. In a small shed, a mower with a folding handle that can be stored upright saves floor space; our guide to choosing a lawn mower covers this. If your shed will hold hand tools, our garden tools guides cover choosing and looking after them; in a metal or plastic shed, plan ventilation from the start to keep them dry.
Do you need planning permission for a shed?
In England, most garden sheds are permitted development and need no planning application, provided that, according to the Planning Portal:
- It is not in front of the house's principal elevation (usually the front wall).
- It is single storey, with eaves no higher than 2.5m and an overall height of no more than 4m with a dual-pitched roof, or 3m with any other roof.
- If it is within 2m of a boundary, it is no more than 2.5m high in total.
- Together with other buildings and extensions, it covers no more than half the land around the original house.
You need permission for any outbuilding in the grounds of a listed building. In national parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites, outbuildings more than 20m from the house are limited to 10 square metres in total, and in these areas and conservation areas a shed at the side of the house needs permission. These are England's rules; elsewhere in the UK, check with your council.
Which to choose
- General garden storage: a pressure-treated shiplap or tongue and groove wooden shed, ideally with cladding thicker than the standard 7–11mm.
- Bikes, e-bikes or expensive tools: a coated galvanised steel shed with vents, bolted to a concrete base. Pick a Secured by Design or LPCB-certified model if security is the reason you are buying it.
- Workshop or somewhere you'll spend time: wood. Metal heats up fast and drips in cold weather.
- Lowest upkeep, sheltered spot: a plastic shed with a floor, fixed down through the floor.
- Exposed or windy garden: wood, or metal with a proper anchor kit. Avoid an unanchored plastic shed.
- Coastal garden: if you choose metal, make it galvanised and keep air moving through it.
Whatever you choose, give it a level, dry base and room for air to move. For more on furniture and storage for the rest of the garden, see our outdoor living guides.
Questions people ask
Is a metal shed better than a wooden shed?
For security, usually yes, especially certified high-security models. For storing tools or using it as a workshop, wood is usually better: Summerhouse24 says it breathes, so condensation is usually not a problem. Metal sheds need vents and a dry base to stop condensation dripping inside.
How do I stop condensation in a metal shed?
Choose a vented shed and leave space around it for air to move. Lay a damp-proof membrane under the base, seal the base rails inside with silicone, and let wet bikes and tools dry before storing them. If it still drips, line the underside of the roof or fit a raised timber floor.
How long does a wooden shed last?
Makers state guarantees rather than lifespans. A dip-treated shed typically carries a 10-year anti-rot guarantee that depends on re-treating it every year; a pressure-treated shed can carry 25 years. A dry, level base and regular coating make the biggest difference.
Do plastic sheds blow away?
They can if they are not fixed down, because they are light. Bolt the floor to a solid, level base using the anchor points provided, and check the fixings before the windy season.
Do I need planning permission for a shed?
In England, usually not. A single-storey shed that is not in front of the house is normally permitted development if it is no more than 2.5m high within 2m of a boundary, with eaves no higher than 2.5m, and no taller than 4m with a dual-pitched roof or 3m with any other roof. Listed buildings and protected areas have stricter rules.
Sources
- Metal Sheds vs Wooden Sheds vs Plastic Sheds, Asgard
- Metal Sheds And Condensation, Asgard
- The Big Shed Debate: Timber, Metal or Plastic, Norfolk Sheds
- Wooden Garden Shed, Plastic, or Metal? Which Material is The Best Choice for Your Shed?, Summerhouse24
- How to buy the best shed, Which?
- Wooden shed cladding thickness guide, Garden Buildings Direct
- Pressure treated vs dip treated wood buildings, Garden Buildings Direct
- Forest 6 x 4 ft Overlap Dip Treated Shed, Gardensite
- Forest Beckwood 6 x 4 ft Shiplap Reverse Apex Shed, Gardensite
- How to prevent condensation in a shed, Gardensite
- Keter sheds range, Gardensite
- Lifetime 10 x 8 ft Plastic Shed, Gardensite
- 15 most asked questions about sheds, Keter
- Metal Garden Shed, Biohort
- Yardmaster 7' 6" x 6' (Nominal) Apex Shiplap Metal Shed Stone Grey, Screwfix
- Outbuildings: planning permission, Planning Portal
- Metal sheds, Mumsnet
- Sheds: wood vs metal, Singletrack