In heavy structural timber framing, the bracing is often done with what we call ‘grown’ curves.
Wood curves are usually limbs of an Oak tree which have grown with a natural bend or bow. The fibrous structures within the wood have a natural tension and compression within them – acting as nature’s equivalent of pre-loading.
The curved tree limbs are ideal timber frame braces because none of the fibres have been cut along the length. The fibres stay intact throughout the length, bound to each other. which maintains mechanical strength.
The alternative; braces from cut Oak curves
As curves don’t exactly grow to order, we can supply a complete fresh sawn through & through board that has been cut to achieve the requirements. The actual shaping is done by the framer. A cut curve is a brace that has been cut and shaped from a blank section of regular, straight-grown, structural timber, usually Oak.
These may be more suitable for use on single-storey buildings, where bracing has less loading, or on new builds which don’t require such authentic attention to detail. They’re a great alternative to ‘grown’ curves. They’re cut to order as part of any fresh sawn Oak cutting list and are priced in the same way.
When would you choose natural grown Oak curves over a cut curve?
A skilled carpenter-framer might select natural grown curves for bracing over cut ones, where a traditional frame is being restored and historical integrity needs to be maintained. Perhaps, in the case where the frame is being built as a residence, if extra strength is required, or if a barn structure requires authentic timber replication then these fit the bill.
In our experience, the timber framers specifying curved braces are skilled craftsmen and know how to work the timber to get the best results, whichever brace they use.
Ordering structural Oak curves for braces
Whether grown or cut, the structural Oak curves are usually supplied as waney edge, through and through cut, to the specified brace thickness. We periodically have stock of Oak curves, kept in our beam yard for selection alongside the rest of our seasoned structural stock. Due to scarcity, we don’t always have them available but they can also be sourced from normal air dried waney edge boards, of which we keep 80mm, 100mm and 120mm thick in Oak.
Our structural stock is primarily for restoration and renovation work, however it is excellent for new build frames. Whilst timber will already have begun to dry and show plits and cracks that also means it is already stabilising, hardening and toughening. It’s also easier to achieve a smooth, clean surface from planing.
Our French-sourced structural timber (Oak) is certified PEFC.
Our British-sourced structural timber (Douglas Fir, Chestnut) is certified Grown in Britain.
Chain of custody certification is provided with your order.
Do you need TRADA Certified Visual Strength Grading BS 5756 for Oak as an additional service? See the pdf below for more information.
