Almost every oak frame company says its work is sustainable. Very few explain what they mean by it. The word has been worn smooth by overuse, and in construction it often means nothing more specific than “we used wood”.
So this is an attempt at a straight answer. Oak framing has genuine environmental advantages over the alternatives, and it also has costs that get quietly left out of the brochure. Both are worth knowing before you commit to a frame.
Timber is the only structural material that grows back
Start with the obvious. Steel is smelted, concrete is quarried and fired, and neither process reverses. A tree is a structural material that a forest replaces on its own, given time and management.
Time is the catch. An oak suitable for framing is somewhere between eighty and a hundred and fifty years old when it is felled. That is not a crop in any meaningful sense — it is closer to an inheritance. The oak in your frame was planted by someone who never expected to see the building.
This is why forestry management matters more than the material itself. Oak from a managed woodland where felling is planned against regrowth is a renewable material. Oak stripped from an unmanaged forest is not, whatever the invoice says.
Where our oak comes from
We buy oak from suppliers in the UK and in France. The French oak comes from government-managed forests, and our square beams come from Normandy. To give a real example, one consignment in 2024 came from Lot 12A in the Creuse and Lot A9 at St André.
All of it comes through sawmills that buy in line with the UK Timber Regulations, which exist to keep illegally felled timber out of the country. Some of it is PEFC certified. Whether a particular delivery carries that certificate depends on whether the French agent holds chain of custody.
We can't run a chain of custody scheme ourselves, because the way our Self Selection Centre works makes the auditing it needs impossible. We still check that our timber comes from the right schemes, and we'd rather tell you the limit than put a logo on the page we can't stand behind.
That means our timber travels. A lorry from France to Monmouthshire is real transport carbon, and it isn't zero.
What timber actually does for carbon
A growing tree takes carbon out of the air and locks it into its own structure. Roughly half the dry weight of timber is carbon that used to be atmospheric CO₂.
When that timber is put into a building rather than burnt or left to rot, the carbon stays locked up for as long as the building stands. An oak frame raised today and standing in three hundred years is three centuries of storage. That is the strongest environmental argument for timber framing, and it is a real one.
The comparison that matters is against what you would otherwise have built. A steel or concrete frame emits carbon at the point of manufacture and stores none. Timber emits comparatively little in processing — milling and cutting, mostly — and stores a meaningful quantity for the life of the structure.
Why we cut green oak
Green oak is timber used unseasoned, straight from the mill, at high moisture content. It is what we use for most frames, and the reason is partly environmental and partly practical.
Kiln drying timber is energy-intensive. Air drying oak takes roughly a year per inch of thickness, which for a 200 mm principal post means eight years of stock sitting in a shed. Green oak avoids both. It is cut, worked and raised while still wet, and it dries in place over the first two or three years of the building's life.
The trade-off is movement. Green oak shrinks as it dries, and it shakes — those long splits that open along the grain. Neither weakens the frame, because a properly cut frame is designed to accommodate the movement. But it does mean the building is alive for a couple of years in a way a steel frame is not, and the detailing around glazing and plaster has to allow for it.
The parts that are less green
Three honest caveats.
Insulation. Most oak frames are encapsulated — wrapped in an insulated panel system so the frame stays visible inside. Those panels are usually petrochemical foam. The frame may be timber but the thermal envelope often is not, and on a whole-building carbon assessment the insulation can outweigh the frame. Wood fibre and sheep's wool alternatives exist, cost more, and perform differently. Worth asking about early.
Foundations. Every oak frame sits on concrete. Nothing about the frame changes that.
Glass. Large areas of glazing are a defining feature of contemporary oak framing and glass is energy-intensive to produce and a weak point thermally. A frame with a fully glazed gable is a beautiful thing and it is not a low-energy decision.
Longevity is the argument people underrate
The most environmentally significant thing about an oak frame is not the carbon in the timber. It is that the building is likely to still be there in two hundred years.
Medieval oak frames are still standing and still working across the Welsh Marches and the Wye Valley. The most wasteful building is the one demolished after forty years because it was never worth repairing. A structure that gets adapted, re-roofed, re-glazed and handed on has amortised its carbon over a period no modern system building will match.
That is a slow argument and it does not photograph well. It is also the one we believe most.
If you are writing a planning statement
Clients frequently need this material for a design and access statement or a planning submission, particularly in the Bannau Brycheiniog National Park and the Wye Valley National Landscape, where sustainability credentials carry weight.
The defensible claims are: timber is a renewable structural material from managed forestry; the frame sequesters carbon for the life of the building; green oak avoids the energy cost of kiln drying; and the expected service life substantially exceeds that of conventional construction.
The claim to avoid is that the building is carbon neutral. It is not, and a planning officer who reads a lot of these will notice.
The short version
Oak framing is a genuinely better environmental choice than steel or concrete for the structure of a building, mainly because of carbon storage and longevity. It is not a zero-impact way to build, and the insulation, foundations and glazing usually matter more to the total picture than the frame does.
If the environmental case is important to you, tell us at the first visit. It changes the insulation conversation, and that conversation is much cheaper to have before the frame is designed than after.
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