Sills. In framing the sills of a house the corner joints usually are made by being halved together as at a, Fig. 22. The sills of a heavy building are frequently fitted together by an open mortised joint, as at 6, Fig. 22. If the sills are built up and spiked together, they should be crossed at the corners as at c, Fig. 22. Large straight timbers are difficult to obtain in long lengths, and are therefore often built up of others of smaller dimensions. Timbers built up in this way have about 75 per cent of the strength of solid timbers of the same size. If the pieces are sprung, or crooked, they often may be straightened by nailing pieces together which are sprung in opposite directions, one piece straightening the other. In a cheap building, the sills sometimes are fitted against each other with a square butt joint, depending upon the boarding and the finish to hold them together. This is bad construction, and never should be used by a carpenter who values his reputation.

Fig. 22. - Framing of Sills at the Corners.

The girders, which extend across the house to support the floor joists and the partitions, are made uniform in size with the sills, and the floor joists are cut to fit them by the same method as at the sills.