Timber pole sheds have been part of the New Zealand farm landscape for generations, and plenty are still going strong. Steel portal frame buildings have taken over much of the market because they span further and don’t rot. We build in steel, but we’ll give you a fair comparison, including where a pole shed still makes sense.
How they’re built #
A pole shed uses treated timber poles set into the ground, with timber purlins and girts carrying the roof and wall cladding. A steel portal frame building uses steel columns and rafters, bolted to concrete footings, with steel purlins and girts. The roof and wall cladding is usually steel on both.
Side by side #
| Steel portal frame | Timber pole shed | |
| Clear span | Wide spans with no internal posts (Steelspan up to 30 m) | Shorter spans, so wider sheds need poles inside |
| Rot and insects | Steel doesn’t rot, shrink or get borer | Treated timber lasts well, but in-ground poles are the weak point over time |
| Straightness | Factory-made to tight tolerances | Timber varies and can twist or move as it dries |
| Fire | Steel is non-combustible | Timber burns |
| Birds | Box steel purlins give birds fewer places to perch, and can be designed into your building if you want them | Timber purlins and ledges attract roosting birds |
| Fixing things to it | Needs self-drilling screws | Easy to screw or nail into |
| Moving or extending | Bolted frames can be extended, or taken down and moved | Poles are set in the ground for good |
| Upfront cost | Competitive, especially as span and size grow | Often cheaper for small, simple sheds |
Where steel needs care #
Steel’s enemy is corrosion, so the right protection matters. Coastal sites need the right grade of steel and cladding, and buildings housing animals need extra thought because ammonia and moisture inside are aggressive to metal. Our posts on coastal sites and cladding finishes cover this. Steelspan frames are Z275 galvanised steel, and we match cladding to the site.
Where timber still makes sense #
For a small, simple shed where internal poles don’t bother you, a pole shed can be a cheaper option, and local builders know them well. Some people simply like the look of timber.
Fitting out a steel shed #
People sometimes worry they can’t hang shelves in a steel shed. If you line a Steelspan building, ply linings can be screwed directly to the steel frame, and shelving and hooks then fix straight to the ply. Steel or timber battens are an option if you prefer.
Our view #
We’ve been involved with both timber pole and steel buildings, and both are good, used in different applications. Some of it comes down to personal preference. Steel holds its straightness and doesn’t split, warp or rot. On open-sided buildings, though, corrosion can be more of a durability issue, and we can allow for that in the design. No one building fits every purpose.
Ground conditions often decide it. Where the ground doesn’t allow poles to be drilled in, timber is ruled out pretty much straight away, and that’s where steel frame buildings come into play. Put side by side on a suitable site, it’s largely preference and the limits of what timber can do. Pricing is often much the same, so it comes down to weighing up the attributes of each and making an informed decision. We’re glad to help you with that.
Talk to Steelspan #
Tell us the size and what’s going inside, and we’ll show you what a clear-span steel building would cost. Use our Easy Shed Quote or call 0800 787 726.
