Building a Timber Barn, continued
To achieve the right "look," there's no beating the tried-and-traditional materials. My frames are built from locally harvested and milled eastern white pine, which arrives at the site still green. Except for rare cases when the lumber comes from an unfamiliar sawmill, all of our framing stock is rough-sawn to full dimension. A 6x6 is literally 6 inches square, and my joists measure a full 2½ inches. Occasionally, but not often, I'll have a client who wants the interior surfaces planed smooth, which requires a simple request to the sawmill and a material upcharge to the customer.
Walls are framed with 6x6 posts on 6- to 8-foot centers. We can spread or squeeze the layout to suit the overall wall length. The posts are tied at the top with a continuous 6x6 lintel.
Typically, we work with 12- to 14-foot-long posts and build a story-and-a-half balloon-framed wall with a level lintel around the full perimeter.
The second-floor joist ledger is notched into the outside face of the posts, which extend above the floor to create a knee-wall, adding headroom and storage space to the "loft." The posts are united with a continuous 6x6 lintel that carries the rafters.
We lay all the posts on sawhorses for gang-cutting. Because the lengths are nominal and rough from the mill, the first task is to square-cut one end. At the ceiling level, typically 8 feet, we notch the exterior face of the posts to let in a 2x10 ledger board. The floor joists rest on that ledger and run to the center of the building span.
Posts are notched for a 2x10 ledger and 4x4 purlins before standing. This barn is being raised over a full foundation on an engineered-lumber deck frame. Pine floor boards will cover the plywood subfloor.
Between the mudsill and the lintel, we notch the posts to fit a 4x4 wall purlin. The purlin is typically located around 4 feet high on the wall and establishes the common windowsill height. This height provides uninterrupted wall area for installing a perimeter workbench.
No headers needed. With both the lintel and the joist ledger carrying overhead loads, individual window headers are unnecessary. Instead, we reinforce the opening cutouts with 4x4 jambs and a butt-fitted 4x4 header, both for appearance and to provide solid nailing for the exterior trim. We often use recycled divided-light wood sash in new pine frames. Not only does this provide the barn with the right look of Yankee make-do frugality, but I can get the sash free from a replacement window contractor.
As a touch of authenticity, the author often uses recycled wood window sash and installs them in site-made pine frames.
Sometimes we let the posts run long and cut them in place. The clients may still be undecided about the second-story windows, preventing us from predetermining the required opening height, or the top of the foundation may be so uneven that it's easier to stand the posts and trim the tops to a level line.
Girders. At the center of the second floor, we typically use a steel I-beam strongback to break the span. While steel isn't a traditional barn-building material, it allows me to eliminate some of the posts required by a sawn wood girder. It's also easier for us to work with than an engineered wood beam, because we don't need multiple layers or metal joist connectors. Instead, the floor joists are nailed to a 2-by cleat set on the bottom beam flange and are secured by a 16d common nail driven down through the top flange. Predrilling the steel flange doesn't take much effort; I have a helper do it. The end of the joist is notched around the top flange and is slightly higher than the beam, to allow for eventual drying shrinkage. Otherwise, the flooring will develop a hump over the girder. To minimize the appearance of the I-beam, we can easily veneer the sides and bottom with 1-by pine.
At center span, joists are carried by a steel I-beam and rest on a 2-by pine cleat that's nailed to the bottom flange. The top edge of the joist is notched to clear the top flange and allow for shrinkage settling, so that a lump doesn't develop over the beam in the floor upstairs.
A nail driven through a predrilled hole in the flange captures the joist to prevent roll-over.
We set the 2½ floor joists on 2-foot centers. To create a stairwell, we leave one joist out, usually at the end of the run. After installing short, diagonal braces between every post and the 2x10 ledger to help stiffen the frame, we're ready to install the 1x10 shiplap subflooring. Alan maps the layout from the center of the deck to ensure that a single board will bridge the steel I-beam. Beginning at one side of the deck, the first board is notched around the posts, and the rest of the floor is laid with butt joints staggered over joist centers. Flooring goes quickly, face-nailed with 3-inch common gun nails, two in the field and three at the butts.
Flooring layout begins at the center of the span to ensure that a single floor board covers the top flange of the steel beam and can be nailed down at its edges. The center of the board eventually comes into full contact with the beam as the joists dry and shrink.
Next, we set the 6x6 lintels, which are scribed in place over the posts, then notched to let in the posts.
The posts are all cut to an equal height and are captured by notches in the lintel beam.
The lintel is first scribed in place.
It is then flipped over and kerfed with a circular saw set to cut 1 inch deep.