Oak Frame vs Pressure Treated Timber

  • April 10, 2023

Considering an oak frame structure or pressure treated timber? We’re here to help. Even though we specialize in oak frames, our goal is for you to walk away satisfied, and part of how we achieve that is by providing information on all types of structures, not just the ones we sell.

We want you to be able to choose the structure that’s best for you. Let’s talk about how the two types compare in these areas:

  • Installation time
  • Effect on Environmental
  • Customisation
  • Cost (initial and lifetime)
  • Quality Control

Is an oak framed structure or pressure treated softwood structure better for me?

Pressure treated structures typically cost less half the price of oak framed structures upfront. However, they often need to replaced every 5–9 years and tend to look cheap. Oak framed structures are much more durable, need less maintenance, and look classy.

Installation Time

Oak Frame

Oak frame structures are designed and manufactured on a CNC machine, the joints are designed to interlock and actually increase in strength over time. From delivery on site to full erection of your oak frame structure can be 3-5 days (larger structures may take longer). Oak Framed structures have to be knocked together as well as fixed together with dowels.

Pressure treated

Most pressure treated timber structures are not designed with interlocking joints which get stronger over time, but you can definitely install them quickly. Often these structures are bolted and/or screwed together. Bespoke structures may take longer, but still typically less than a similar Oak Frame or brick structure.


Oak framed structures are designed to last much longer than pressure treated timber, but the installation time is longer. Winner: Pressure treated Timber

Effect on Environment

Oak Frame structure

Oak is a naturally rot and insect resistant timber, there are no chemicals added to the timber in the process, it achieves up to 25 years resistance to rot when in the ground and over 100 years when kept above the ground.

Pressure treated timber

Pressure treated timber is coated with toxic pesticides, This allows the timber to last a long time without rotting when used for outdoor structures This also means that the timber will not readily decompose in the ground and even when it does – It may leach toxins into the soil. Pressure treated timber is regarded as hazardous waste and is not readily recycled in the UK. Burning pressure treated timber gives off toxic fumes so this is not an option either.


Pressure treated structures may last 5-9 years but they are not easy to dispose of at the end of its life. Oak Framed structures reused, recycled or even composted when it is no longer required. Winner: Oak Frame


Oak Frame

Oak Frame structures can be manufactured to any shape or size. While you can choose a wide variety of standard designs, you are not limited to these.

Customised designs may cost more but there are no real limits on the designs.

Pressure Treated

Most pressure treated structures are supplied as standard structures, Some can have accessories and features added, but the options for overall shape and design are limited. . accessories and features cost more, but still typically less than a similar oak frame or brick structure.


Pressure treated structures can have accessories and features added, but the options for customisation are limited. Oak Framed structures can be manufactured to virtually any shape, size or design. Winner: Oak Frame

Cost (initial and lifetime)

Surely, a pressure treated timber structure is cheaper than an oak frame structure? you could be wrong if you look at the life cost of each.

Oak Frame

DIY-ing an Oak Frame structure can cost between £10,000–£30,000, depending on the structure size and any upgrades.

Most oak frame projects cover both manufacturing and installation, which costs £15,000–£50,000 altogether. As usual, you’ll pay more for extensive landscaping, accessories, and other features.

Long-term, your only serious maintenance expenses will be in cleaning and oiling if you choose to protect your structure from UV light. You’ll spend less than £1000 over a ten-year period.

Oak Framed structures have a high residual value and are an attractive proposition for prospective buyers of your property.

Pressure treated

Most pressure treated structures cost at least £5,000 less than similar oak framed structures so this may seem like a win for pressure treated timber.

If you love to DIY home improvement, a pressure treated structure may be your Everest. Someone who wants a completely DIY pressure treated structure may spend under £5,000. Base pressure treated timber packages from most joinery shops typically cost £3,000–£5,000, while ready-to-use pressure treated structure packages will typically cost £5,000–£15,000.

The pressure treated structure needs to be replaced every 5–9 years, costing £3000–£5000, which includes the labour and materials.

How this adds up: the low initial cost of the structure could be offset within the first ten years after construction, and over the entire lifetime of the structure, it will cost thousands more than an oak frame structure.

On top of the initial and lifetime costs, you’ll need to read your whole structure warranty. The warranty often includes fine print that makes a repair ugly:

  • The warranty only offers to replace damaged components of the structure, this can mean a patchwork of new and old timbers
  • The warranty does not cover any labour, fixings, or other expenses.
  • The warranty does not cover components of your structure that are starting to rot but still ‘structurally sound’
  • The warranty only covers timber affected by insect or fungi attack, if your structure falls down because the screws and or bolts have corroded – this isnt covered. The irony here is the chemicals used in pressure treatment actually causes corrosion of hardware and fasteners (Galvanic Corrosion)

Pressure treated structures are cheaper upfront and may be the better option if you’re on a budget and can avoid the long-term costs. Oak frames are a bit more expensive initially but offer lower costs in the long run. Winner: Oak Frame

Quality Control

Oak Frame

Oak frame structures are fabricated on a CNC machine and sent to the customer with an installation drawing, The assembly of an oak frame structure involves tight joints when lock into place over time.

Pressure Treated

Similar to an oak framed structure, Pressure treated timber is fabricated on a CNC machine however, the joints are not designed in the same way to get stronger with age. Pressure treated timber also undergoes a chemical treatment process before the timber is fabricated, this process is poorly managed or controlled resulting in insufficient treatment of the timber. This means that the service life of pressure treated timber can vary from 2 years to 10 years with no way to discern a well treated timber from a poorly treated timber.


Pressure treated structures are made on similar machinery to oak frame structures but that is the only similarity. Oak Framed structures are naturally rot resistant and require no chemicals, They are also designed in a way to increase in strength as the timber dries out and shrinks. Winner: Oak Frame

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