Timber framing 101 -Mortises

More than two feet of this post's rotted end had to be removed. A chainsaw is the fastest and generally most accurate way to do this.

Using a carpenters square, Jason marks the cuts for a mortise and its housing on one of the original posts. A mortise is a hole in the post or beam that accepts a tenon. The tenon is the extension of a beam or a knee brace that fits into a mortise. A housing is an inset in the post larger than the mortise itself. Most of the weight of a beam is actually transfered to the post through the housing shelf.

An electric mortiser, incorporating a small chainsaw, is used to rough cut the mortises.

Next, the bottom of the mortise is cleaned out using various chisels.

Then the housings are cut, first using a hand saw or circular saw, the wood is chiseled or chopped out, and finally the cut is "fine tuned" and a slight inward angle added to make the joint clean and tight when a beam is inserted. Dave is roughing out the wood with a chisel and a very large mallet.