It’s been a productive month. The structure is back on the new slab and the main framing and sheathing is complete.
The ADU walls now sit on a new mudsill of pressure-treated 4×4. I’m using a rubber gasket stapled to the bottom of the 4×4 to isolate the wood from the concrete and to also help make the wood-concrete joint air-tight.
I ordered the gaskets from Conservation Technologies: http://www.conservationtechnology.com/building_gaskets.html
(They are also a good source for Shim Screws for window and door installation.)
The main changes to the existing Garage framing was the installation of a 4×12 Glulam beam which will become an exposed feature running the length of the ADU. The rafters had to be cut down to fit against the new beam. An extra sillplate was added at the top of the wall as the existing sillplate was looking gnarly.
The architect specified Simpson Strong-Drive SDWC TRUSS Screws to attach the rafters to the sillplates rather than the usual hurricane hold-down ties. It’s as strong as a hold-down connector but faster to install – just drive one screw vs. nailing in 10 nails per connector. The kit that Simpson provides includes the required drive-bit, also a jig for getting the entry point and drive angle correct. The screw head is orange which makes it easy to verify that all rafters have been fastened.
On the north and south facing walls it was possible to retain most of the existing studs however the wood on the east and west walls had to be replaced due to extensive rot in the bottom of the studs.
The existing rafters were also retained, however doubled up to provide extra strength. The old wood had a greater tendency to split when driving nails.
The plywood wall sheathing was installed vertically so that all edges fell on studs/sillplates for maximum nailing strength. (Had they been laid horizontally then blocking would have been required between all studs.)
The roof sheathing was laid horizontally to maximize the number of rafters tied together by each sheet.
Panel spacing was around 1/16″ for the walls, and increased to 1/8″ in the roof sheathing where I’m thinking there is greater possibility of thermal expansion/contraction.
The builder has provided much of the construction lumber. I’ve been using Parr Lumber for some items