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In defence of green oak


People often ask why it is that we make oak frames out of freshly sawn green oak with a high moisture content rather than using more stable dry oak.

Well, having laboured hard this week over a small glazed gable frame made from bone dry oak, I’m feeling well placed (and motivated) to answer.

BECAUSE IT’S EASIER!

Green oak will bend to your will, cleave along the grain, respond compliantly to a reasonable sharp chisel or saw, and pretty much do what you ask it to do. Air dried oak on the other hand will sap your strength, blunt all your tools in a heartbeat, mess with your mind and leave you weeping on the workshop floor in a dusty heap.

Here’s the fruit (dried?) of my labour:-

Oak Frame Gable by Castle Ring Oak Frame

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“Shrinkage” – don’t be alarmed‏!


Green Oak and Timber Framing

Timber framers work with green oak because it can be sawn and chiseled easily. Dry oak is merciless and will blunt your edged tools as if you were cutting through metal.

The down side of using wood with a high moisture content is that as it dries it shrinks. Not only does it shrink, but it shrinks in different directions – tangentially (lots), radially (quite a lot) and longitudinally (barely at all). What all this technical stuff means in lay terms is that timbers will invariably develop big splits or shakes, and in addition will twist and cup to varying degrees.

Green Oak

It’s an important part of the framer’s job to be aware of likely movement and shrinkage so that the timbers can be selected and oriented appropriately. In this way the structural integrity of the frame is maintained.

The cracks can sometimes look alarming as they appear, but rest assured, they will settle down, and one of the many extraordinary properties of oak is that as it gets older it gets harder.

Green Oak

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Oak frames and staining


It’s an irritating fact of life that a green oak frame will invariably require cleaning once it has been erected and made weather tight.

From the moment it is felled and converted into timbers, the oak will start to bear the marks of it’s physical journey from tree to frame.

To start with, tannins in the oak react with iron saw blades during milling producing distinctive blue black stains. Then when we timber framers get our grubby clomid online mitts all over it in the workshop, we leave a trail of pencil marks, calculations and dodgy doodles compounded by copious numbers of highly visible ink lines. Add to this a muddy building site and more Great British weather leeching out tannins to create yet more brown staining, and the frame can end up looking a little the worse for wear.

Green oak - timber framing and staining

But fear not. The oak cleaner is there to help……to be continued!

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Tusk Tenon


The tusk tenon is a useful joint to choose when you need to connect horizontal timbers (such as in a floor layout) without weakening either beam too much. The tenon extends from some point up from the bottom surface, usually at the central or neutral axis of the beam into which it will locate.
Castle Ring Oak Frame tusk tenonsThis is all about preserving continuous beam fibres at the top and bottom of the morticed beam. What does “continuous beam fibres” mean? It means your house won’t fall down!The upper shoulder is cut at an angle to increase the strength or “shearing” area of the tenon, along with a “step” below the tenon for the same reason.

Castle Ring Oak Frame timber frame tenon

The great thing is that once the joint is assembled you’ve no idea it’s there.

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