Colonial Wall-Framing Methods

Scribe Rule

• In scribe-rule framing, the joints in one timber are custom cut to fit the joints in a second timber. The carpenter uses specialized transfer tools to transfer the dimensions, along with any irregularities in the first timber, to the second timber. These marks, known as “marriage marks,” ensure a tight joint. Even though timbers may perform the same function, they aren’t interchangeable when this method of framing is used, because the connection between each pair of timbers is unique. Scribe-rule framing is useful when joining hand-hewn timbers that aren’t uniform in size.

Square Rule

• When sawmills started turning out timbers uniform in size, carpenters developed new ways of framing. The square-rule method of framing uses recessed joints. By cutting the joints on a common plane, the timbers can be treated as though they are uniform in size no matter what their actual shape is. This method of framing is the one most commonly used today, and allows for the use of interchangeable parts.

Joining

• The mortise-and-tenon system of joining timbers is the one most commonly used in timber framing. This system includes a male end or tenon cut onto the end of one timber and a square-cut female receptacle or mortise on a second timber. Pegs or hardwood dowels can be used to lock the two pieces in place. Adzes are used to form the tenons and mortises, and the process is very labor intensive.

Changes

• Timber-framed buildings have exposed frames that can make a house look unfinished. To address this problem, carpenters developed different joining methods that also served as decoration. These techniques didn’t change the way the timbers were fastened, but they did change the appearance of exposed beams by adding symmetrical sloping edges, rounded moldings or other decorations that some people found more aesthetically pleasing.

Wood

• Hardwood like oak was originally used to make timber wall frames in colonial New England. However, by the mid 1800s, softwoods like spruce, hemlock and pine became more common. These woods, along with Douglas-fir and white fir, don’t tend to warp, are easy to work with and hold nails well.