Post and Beam Frame | Library builder

The “beam” component of “post and beam” timber framing usually refers to a heavy top plate, sometimes called a girt, or it could refer to a girder. Girts will often be supported later by infilling the individual panels of the building’s perimeter. In this book, I use the word “panel” to refer to the spaces between posts around the perimeter. Girts can also gain strength by the use of intermediate posts, between the major posts. If not called upon to provide a joining surface for two consecutive girts, these intermediate posts can be less substantial, thus less expensive. An example of this is our garage at Earthwood. See Figures 2.12 (photo) and 2.13 (post and girt plan.) We have full-sized eight-by-eights at each corner of the 24-foot by 28-foot (7.3-meter by 8.5-meter) structure. In addition, we have eight-by-eights halfway along the walls. But, providing further strength to the girts, we have what I think of as secondary posts, still substantial four by-eights, laid up so that the eight-inch (20.3 centimeter) dimension corresponds with the 8-inch thickness of the wall. The sides of the building, therefore, have four panels

on the long side, each about seven feet in length including the posts, and also four panels on the south (gable) side, each about six feet long. The 24-footwide north side features a 16-foot garage door, with little four-foot panels on each side. An 18-foot-long (5.48- meter) eight-by-eight carries the girt system over the garage door. This large beam can also be thought of as a giant lintel over the garage door.

I was told at a building supply that the rough opening for our double garage door was 8 feet high and 16 feet wide, and it was framed accordingly. In reality, the height dimension turned out to be seven, not eight, feet (2.13 meters). The door fit with a foot to spare. We later hung a horizontal two-

by-eight from the eight-by eight with 10-inch pieces of two-by-eight material, filling the spaces with cordwood masonry. Because of this mistake, our garage is actually a foot higher than it needed to be, causing me to do a bit of extra cordwood work.

In the case of the girts at our garage, they were well-supported during construction, with temporary diagonals screwed to the external frame to prevent racking of the building due to wind loads. Later, individual diagonals would be removed and panels would be filled in with cordwood masonry, which also serves to prevent racking. We do not have any true girders at our garage, as we have at the Earthwood house. It is the clear-span girders in a post and beam frame that need to be engineered for both shear and bending. Appendix В gives an example of this.

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