Q&A: A "Half-Timbered" Tudor with Stucco

A.Will Beemer, co-executive director of the Timber Framers Guild in Becket, Mass., responds: You are proposing an infill system, as opposed to the usual enclosure system, which wraps the entire structure with insulating panels. Traditional infill systems used materials such as adobe or wattle-and-daub. You are probably planning to build stud walls covered with stucco between the posts of the timber frame. Unfortunately, the finishing details where this infill meets the timbers would prove daunting.

Your proposal could work, but the success of the system would depend on a number of conditions: You must be located in an arid climate; you must use dry timbers; and you must be meticulous about caulking. In a mild, dry climate, such as that of the arid Southwest, you would not have the moisture migration and condensation problems we do in the Northeast. In a cool, damp climate, your timber frame is at risk of rotting from rain on the exterior or from the condensation of interior moisture on cold surfaces near air leaks.

Most timber frames are built with green timbers that shrink as they dry. Because shrinking timbers will magnify the difficulty of caulking any gaps between the infill system and the timbers, you should begin with dry timbers. One option is to use dry reclaimed timber, although such timbers are more expensive than green timbers.

Choose a species that is rot resistant and that swells and shrinks little with moisture changes. Cedar would be a good choice, although cedar is expensive and not very strong. I would probably use Eastern white pine, which shrinks very little, and get around the rot-resistance problem by keeping the frame well off the ground and protecting it from the weather with wide roof overhangs. Water does the most damage, not exposure to sunlight or air.

Any gaps that open up between the infill system and the drying timber would have to be caulked, both inside and out. This caulk could be the infill material itself (adobe, etc.) or one of the new synthetic caulks that bonds to wood and masonry. Since wood can swell and shrink with humidity changes, these caulk joints will require vigilant maintenance. If all of these requirements are discouraging, and you want an easier way to keep your timber frame lasting a few centuries, you should wrap it in an insulating skin.