Timber Framed Buildings

I was inspired to write an article after looking at this amazing photo. According to the website EXPLORINGGB.COM, "The Great Barn at Harmondsworth is the largest standing medieval timber-framed structure in Britain."  It was built in 1425 and still stands proudly today. Bear in mind that there were no nails in this construction; the timbers were held together with mortise and tenon joinery. You will often see pegs driven through the joint to lock it in place.

This carpentry joinery has been implemented for the last 7000 years, so it's no surprise we are still using it today, It was very important for barns, which needed a large space in the middle of the floor for threshing grain—in other words, sturdy roof framing with no post in the center. Nowadays, since machinery does most of the work, large barns often stand empty.  Nonetheless, timber framing is far from extinct; right here in Pennsylvania many Amish builders continue to specialize in these time-honored structures, using techniques inherited from their ancestors. At the same time, modern timber framing companies sell custom kits for homes, though the cost tends to be prohibitive for the average home owner.

In the old days, before sawmills came along, square timbers were hewn by hand using adzes, broadaxes, and draw knives. In stone house basements today, you can still see the evidence of these hand-hewn tools; the surface of the logs are rough, and you can see where little slips of wood have been chopped off. Also, because the mortises and tenons were individually measured and cut by hand, none of the joints were interchangeable. So the carpenter marked both timbers with "carpenter marks" or Roman Numerals so they could be matched in the future when the building was erected. These carpenter marks can still be seen today in old barns. 

The majestic frames are best appreciated on the inside of the barns; usually the exteriors are rather common looking and nondescript. The same applies to many old houses, which were cladded to protect the wood. The exceptions are the famous half-timbered homes we often associate with the Tudors, though they were actually common for a century before that. They are called half-timbered because big logs were split in half, and the flat side was placed on the exterior. So the whole building frame was exposed, and the large spaces between the timbers was infilled with wattle-and-daub (willow branches stuffed with mud or clay), then later with brick and stone; all the infill was coated with plaster. 

Half-timbered homes were so popular we saw many them reproduced in the Tudor Revival period of the early to 1900s. As the century progressed, timber frames started to be superseded by post-and-beam construction, which looks very similar. The big difference is that post-and-beams use metal fasteners and connectors rather than mortise and tenons. Sometimes the connectors are hidden, sometimes not. It takes less skill to construct these homes, and as a result they are less expensive to build. But the end result is equally pleasing to the eye. 

Now, we have pretty much come full circle and totally enclose our timber framed houses with exterior cladding, often using modern SIP (Structural Insulated Panels) panels—then, on top of that, regular shingles, or builder's choice of siding. The SIP panels come with a rigid foam core for insulation, sandwiched between two structural facings, usually OSB (Oriented Strand Board). Again, they look like pretty normal houses on the outside, and you won't notice the timber framing until you go inside. Then… wow! Takes you right back to our ancestors.