Truss Design for Energy-Efficient Shed
The time is getting close to start construction on my energy efficient shed. Some quick background:
– 8’*12′ (can’t build larger for building code reasons)
– Pacific Northwest (climate very similar to Seattle but a little colder)
– I want to be able to store stuff in the shed throughout the winter that cannot freeze.
– I will be insulating the shed and hope to keep it from reaching freezing inside with a minimal amount of energy (e.g. turning on a 100 Watt lightbulb whenever it is going to drop below freezing – ideally hooked up to an anti-freeze thermostat.)
– Basic plan is for 6″ walls insulated with rockwool and a vapour barrier on the inside. 6″ or 8″ insulation in the floor and the attic. No plans for external insulation.
– Attic will be vented (soffit vents and a ridge vent)
– Passive de-humification (moisture absorber such as DampRid as needed)
– No windows or vents. Air tight. Single insulated steel door.
I’m designing the trusses now. I want to have a minimum of 6-8″ of insulation wall to wall.
I looked at the possibility of building Raised Heel/Energy Trusses but it looks like it complicates things significantly. (Option on the left of the diagram)
So I’m now proposing the option on the right of the diagram. I’d use gussets on all three corners. The bottom 2*4 sits directly on top of the wall. It seems like this hits all the criteria:
– Easy to build (no birdmouths, etc.)
– Seems like it would be adequately strong in all the required directions.
– Gives me height above the top of the wall to install insulation while still allowing an air gap above.
Am I missing anything? Any suggestions? Seems too simple – and I haven’t seen others done like this – what am I doing wrong?
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