I have a 10×20 shed in the back yard, and as my wife and I get increasingly addicted to woodworking, it is becoming “the workshop” where we spend a lot of time on our shared hobby. We live in Austin [where it will be 101° F today] so we’re focused on making the building cool enough. Heat isn’t much of a concern.
We’re still very new to building stuff—I’d classify us as “advanced novices”—so forgive any silly mistakes below :-D
More specs on the building
Again the size is 10×20. It sits on a mostly-stable concrete slab and we have a bare concrete floor. 2×4 studs (unevenly spaced) which are skinned somewhat loosely with painted plywood and exterior trim. Totally unfinished on the inside. Gable roof with the ridge running along the major axis, probably about 20 – 25 degrees, plywood decking and galvanized steel on top. The “attic” space is not separated from the general interior space—there is no ceiling, only open trusses. The attic is not vented in any way, but we do have two good-sized operable windows (at typical interior height) at either end of the shed, which we usually leave open with the screens. And finally, there’s a well-sealing pre-hung door in the middle of the broad side.
This building is definitely leaky in terms of air flow, because hey it’s a wooden shed right? :-D
As we add insulation here, I don’t imagine we would choose to make it more airtight; that might be a losing battle, and we’re not that concerned about energy efficiency anyway.
What we’re up to so far
The building has a subpanel of its own, and a half dozen outlets and a couple of switches. All of this is (unfortunately) wired on just one breaker from the subpanel, so I know I’m going to need to do some re-wiring (utilize multiple breakers) in order to e.g. separate the lights from the eventual table saw, etc.
Meanwhile we purchased a refurb 6000 BTU window A/C unit, and this morning we are in the process of mounting this in a thru-the-wall fashion. We’re going to get it rigged up and probably test its cooling capabilities even before we’ve done any insulating work.
The plans from here
My thinking is, we’re probably not going to be spending long hours in this shop except on the weekends, so I don’t see us leaving the small AC unit running when we are not in it. This means the temperature and humidity levels will be changing frequently inside. Am I already on the wrong track here?
If not, then here’s what we’re thinking for insulating / closing in the shed:
Finally, the questions
- Some kind of moderate insulation (batts or rigid foam) in the stud spaces and roof rafters
- Close over the insulation (perhaps loosely) with thin plywood sheathing as the interior walls
- Leave the “attic” space inside the gable open to the interior with the trusses still exposed, so that space can be used as an overhead storage loft, or a place to route wiring and dust collector hoses, etc.
- I know that if I was working on a true interior space, or I was in a colder climate, I would definitely have to worry more about condensation and dew points, etc., think about vapor barriers, and so on. But, given that this is a leaky building that will probably always remain so … do I need to worry about that or am I doing fine with the plans above?
- The hottest part of the building right now (by far) is the metal roof and the heat coming through it. Will insulating here in the rafters be enough to make a difference? Or do I also need to consider adding some kind of attic vent or fan (passive or forced) to move the hot air out of that space?
- What have I missed? What would you do here? What are we about to do wrong?
Thanks A BUNCH for reading this far. Appreciate all your help.