New materials, old ideas

The more I look at the way our modern extension is being built, the more I am convinced that it is a fitting companion to the original 16th century oak-framed house. There is not a great deal of difference between the basic structural concepts, and only the materials and methods of fixing are new.

The biggest difference is that an old oak frame is mortised and tenoned rigidly with a few very heavy timbers while a modern softwood frame uses more but lighter timbers fixed with nails and steel hangers, and plywood sheets to increase rigidity. A modern construction can also use some big timbers, eg our glulam roof beam which runs the length of the building.

The timber frame takes shape
The timber frame takes shape
The roof timbers are added, with a Glulam central beam
The roof timbers are added, with a Glulam beam
The panels are infilled with insulation, with plywood panelling behind
The panels are infilled with insulation, with plywood panelling behind

The extension is a conventional modern timber-frame building. First, a wood frame was constructed piece by piece by Terry Booty of Booty Builders and his team, Andrew and Tim, on a low brick base; then they filled the spaces between the timbers with blocks of Celotex insulation, today’s equivalent of the hazel sticks and clay daub that fill in the panels of the old house.

The new timber is treated softwood, which I suppose is a lot less likely than oak to be here in 500 years time, but it is still a pretty durable material. The insulation is a hi-tech foam that takes us well above the new building regulation minimum, and will be much warmer to live with than clay. (One of the advantages of timber frame construction compared with blockwork or bricks is that it much easier to stuff loads of insulation between the panels). The fastenings of steel may not last as long as wooden dowels but they are cheap and easy to use.

Putting all those changes aside, if you stripped the old house back to its frame it would look quite similar, from a distance, to these pictures of the new extension. Its original builders would have been on site fitting individual timbers together, using different methods but with an objective – constructing a wooden frame to be infilled on site – much the same as Terry’s expert team, who made the basic structure in an impressively short time. The detail has changed, of course, but not the underlying idea of how to make it stand up as a rigid structure that keeps out the weather.

I am convinced that modern materials using an old concept are just as authentic as new oak framing for building an extension to a mediaeval timber building. In fact, it is hard to stop an oak framed extension with exposed timbers looking like a poor pastiche of the original. It can be done, but there are very few examples around Suffolk that manage it.

The first layer ofroof insulation is added and protected with a plastic membrane
The first layer of roof insulation is added and protected with a plastic membrane

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