Black and white photograph of an oak log.


Responsibly sourced materials

The Timber Frame Company uses sustainably sourced timber for all our frames.  We support the Forestry Stewardship Council and PEFC schemes by purchasing accredited oak, larch and Douglas fir from sustainable sources wherever possible.

How oak is graded for structural use

Wood is an amazing substance.  It is renewable, recyclable and strong.  Its qualities differ depending on how it's cut (across or along the grain) and it has a beautiful appearance.  How the oak or Douglas fir is graded and chosen for each specific task is fundamental to the performance and look of the finished frame.  This is particularly important in post and beam framing, which relies on just a few large section timbers: every timber and joint is critical to the frame's performance.

Before any timber reaches us it will have been graded under a recognised standard.  We also have our own timber grader (registered under the CATG scheme) who can check the quality of the oak we receive.  From then onwards, our carpentry teams constantly reassess and consider each piece as a frame is manufactured.

The oak we buy is graded to THA/THB and TH1/TH2 (BS5756 BS EN 14081:1:2005).  The grade specified tells the structural engineers which set of numbers to crunch when they work out if the frame will stand up THA/1 is better structurally (but more expensive) than THB/2.  These grades fall into two main strength classes for temperate hardwoods; THA D40, THB D30.


Timbers are then carefully selected, by experienced carpenters

Within each grade, the individual oak timbers will show substantial variation.  Although the entire lot is graded as suitable for structural use, there is a big difference between 'low graded' and 'high graded' stock.  Properly trained carpenters are taught how to select timbers carefully to enhance their structural and aesthetic appeal within the finished oak frame.  For example, they will ensure that timbers are not cut in a manner that would place a knot at the end of a beam, or within a joint, where it may reduce the performance of the finished frame.  On the other hand, some knots look nice:  in which case they may place the timber within the frame so that it will be visible in the finished structure.


We use our own grading system for key parts of the frame

This care and attention to detail requires experience and professionalism.  The selection of timbers makes a huge difference to the quality of the frame and our standards match or exceed the structural requirements of the British Standard.  Over a period of years we have developed our own, more exacting, timber standards for particular requirements for example where we specify ‘glazing standard', the oak must be free of knots and have a very straight and parallel grain.

You'll see plenty of beautiful, carefully selected timber in the projects on our portfolio.  Here are some of the timbers that didn't make the grade and why.