Steel Frame vs Timber Frame for Farm and Commercial Buildings in Scotland

We build steel. So you'd expect us to say steel every time. But timber framed farm buildings have been going up across Scotland for generations, and for some buildings they're a perfectly good choice. If you're weighing the two for a new shed, workshop or commercial unit, this is the honest comparison we'd give you over a cup of tea.

The basics

Steel portal frames use hot-rolled steel columns and rafters, connected rigidly at the eaves and apex, with lighter purlins and side rails carrying the cladding. The rigid connections let the frame span wide openings without internal columns. See our portal frames page for how they're put together, or portal frame basics if you want the parts named in plain English.

Timber framed agricultural buildings traditionally use timber posts and trusses or glulam beams, with timber purlins and rails. They're common for smaller sheds, livestock housing and buildings where timber cladding is wanted for looks or ventilation.

Span and clear space

This is where steel tends to win clearly.

A steel portal frame can give large clear spans without internal posts. For a machinery shed, grain store or commercial unit, clear space means you can turn a tractor, stack bales wherever you like, or let the building to a tenant who wants an open floor. If the building is a let unit, the commercial steel buildings introduction is the decision list before you compare frame materials.

Timber can span reasonable distances, especially with engineered timber like glulam, but for wider buildings it typically needs bigger sections or internal posts, and the cost climbs.

Height and doors

Big vehicle doors and high eaves are easier to achieve in steel. If you need to get modern farm machinery or HGVs in and out, steel portal frames make tall, wide openings straightforward.

Durability

Steel, properly protected with the right coating system, is durable and doesn't rot or get eaten by insects. Corrosion risk depends on the environment: livestock buildings, coastal sites and wet areas need appropriate protection.

Timber that's properly treated and detailed can last well, but it's more vulnerable to rot where it's kept damp, for example at post bases or where muck sits against it. Good detailing keeps timber dry.

Livestock housing is an interesting case. Ammonia and moisture are hard on both materials. Steel needs a suitable coating; timber needs protection from wetting and contact with muck.

Speed on site

Steel frames are fabricated off site, then bolted together on site. Erection is usually quick once the foundations are ready. Timber frames can also be fast, especially prefabricated trusses, but large timber buildings often take more on-site work.

Fire

Steel doesn't burn, but it loses strength at high temperatures. Timber burns, but large sections char on the outside in a way that can be predictable. For agricultural buildings, fire is often more about what's stored inside (hay, straw, fuel) than the frame.

For commercial buildings where people work, fire safety is designed into the building and the building warrant, whichever material you choose.

Adaptability

Steel frames are relatively easy to extend: add bays on the end, add a lean-to on the side. Timber can be extended too, but matching the existing structure and loads can be trickier.

Looks and planning

In some rural locations, the look of the building matters to planners. Timber cladding is sometimes preferred for sensitive sites. Note that you can put timber cladding on a steel frame. The frame and the cladding are separate choices.

Cost

We don't publish guide prices, because every building is priced to its own size, loads and specification. In broad terms:

• For small, simple sheds, timber can be competitive.
• As span, height and loads increase, steel usually becomes the more economical way to get a large clear space.
• Snow and wind loads in Scotland can be significant, especially in exposed or upland sites. The frame has to be designed for your location, which affects both materials.

The fairest comparison is two priced designs for the same building, not a rule of thumb.

Insurance and resale

Some insurers and buyers have views on building types. If insurance, finance or resale matters, ask your insurer or agent whether they have a preference.

So which should you choose?

Steel often makes sense when:

• You need wide clear spans or tall doors
• The building is for machinery, grain, commercial letting or a workshop
• You want to extend later
• Speed of erection matters

Timber can make sense when:

• The building is small and simple
• You want a traditional look or timber-specific ventilation
• The planning context favours it

Getting a price

Tell us the size, use and location of the building. We design, fabricate and erect steel frames, cladding and doors from our Penicuik workshop, and we price every building individually. See our agricultural sheds, farm buildings and commercial units pages, or get in touch.

FAQ

Is a steel building colder than a timber one?

The frame material makes little difference to temperature. Cladding and insulation decide how warm a building is.

Can I have timber cladding on a steel frame?

Yes. Timber space boarding and cladding are often fitted to steel frames, particularly on livestock buildings and in rural settings.

Which lasts longer, steel or timber?

Both can last a long time when they're properly specified, protected and maintained. Steel needs the right coating for the environment; timber needs to be kept dry.

Do steel buildings need planning permission in Scotland?

That depends on the building, the location and its use, not the frame material. Some agricultural buildings can proceed with a prior notification; others need full planning permission. See our planning guidance or speak to the council.

Can a steel building be extended later?

Usually, yes. Adding bays or a lean-to is one of the advantages of steel portal frames. It's easier if the original design allowed for it.