Day Twenty

October 21, 2023

installing purlins across the roof

all roof, all day

well, maybe not all day. saturday is a half day for the crew, optional for the volunteers.

when last we saw the roof, we were finishing up the first layer - plywood. in the picture above you see that gray insulation has been installed over the plywood, and purlins (the horizontal slats) are being installed. they serve a few purposes. probably more than a few, but i only know a few. they help to hold down the insulation, they create a track where another layer of insulation will be installed between them, and they provide an anchor on which the metal pro-panel roof will be mounted.

once you start covering the rafters with layers - plywood, insulation, purlins, insulation, metal roof - you must be able to find the structure is beneath it. i realize this is an obvious statement to anyone who’s worked construction. you must be able to measure to it accurately, or you wind up with a bunch of screws poking through the plywood and missing the rafters and bracing. more than a little conversation was had about the measuring, and we had to remove and redo a couple purlins after looking at the roof from underneath and seeing a bunch of ‘shiners’ (a wayward screw).

in the pictures below you can see how the white hard insulation has been brought up and joined to the insulation coming down from the roof. this completes the enclosure of the ‘thermal wrap’ with the insulation we’ve seen as we built up the surrounding berm. you can also see the black, chimney tops of the cisterns, that are now buried by the berm.

the walk around. you can see that insulation has been installed around the front greenhouse wall.

i’ll finish up with a thought and a couple videos.

i did my coursework for the earthship academy in 2020. i did well on the final exam, which was good for my ego, but that said, being on-site and participating in this build is invaluable. study, married with hands-on experience.

the first video is panning around the interior from within the greenhouse.

this next one is walking up the berm to the roof (a route which i’ve travelled a hundred times at this point), which has been covered over in plastic as we leave for the day.