Timber Frame Compost Hutch Design

A few years ago we built a chicken coop using wood from a dead spruce on our property. You can see a video of the whole process in parts I and II. We also had a few blog posts with details of the build and plaster walls. We have plans to build a new timber frame workshop classroom for the institute in coming years. In the meantime, we will practice our skills by building a compost hutch. Our goal is to build it using as many supplies from from the local environment.

The hutch measures 18 × 6 ft with three bays. Each bay has replaceable wooden sides and allows for a series of compost piles at different stages of decay. The roof is thatched with wheat straw. The wood may come from nearby trees cut by a neighbor arborist. Although we plan to hew some of the logs, we will likely hire another neighbor with a small mill to cut out the timbers and planks. Our goal is to open up the building of this as a series of workshops over the summer of 2021.

The frame has four bents (segments) held together by a bottom sill and top plate. The rafters are at 50° to facilitate rain and snow running off the thatch. The posts are 6 × 6 in but the sills are only 4 × 6 in as they do not need to support the weight of the frame, just keep the feet of the posts together. The plates are 6 × 6 in. Each bent has two braces measuring 2 × 4 in, as this small frame only needs modest bracing. The top plate also has two braces on each side, measuring 3 × 5 in, although this dimension receives less stress than across the bents (front to back). The rafters are 3 × 5 in at 2 ft on-center spacing with 1-×-3-in purloins at 9-in intervals. The posts are bound into bents by 6-×-6-in beams held by a dovetailed, extended through tenon with wedges. The posts fit in the sills and plates with stub mortise-and-tenon joints. The rafters meet in an open mortise-and-tenon joint at the peak and rest on a bird-mouth joint on the plates.

We’ve gone on to create cut diagrams for each of the timbers.