Before deciding on HLG, I was also looking at Sol-strips (don't have a link handy) you can just mount them on a sturdy aluminum sheet-pan and add-subtract-change spectrum with different strips, etc. I decided against it because it looked like a money-hole I the long run - "oooh a UV strip I can add..." and stuff like that - but that's just how I am.
*packs bowl and settles in*
I have a 3br 2bth house to myself, and could put my permanent room anywhere, to include knocking down walls if I wanted. I may build a perfected room later, but here's the stuff I thought about while deciding
separate flower -veg, obviously, but completely separate. Separate exhaust fans (not much smell, and not as much air needed in a veg room) intakes, basically 2 separate environments.
not as much height needed for veg either.so I was thinking about a half-height room. with the veg part on top (easier to work on stuff), and just storage underneath, or a separate clone room or seedling mat set-up.
Either big enough to walk in and close the door, or small like a closet. A 'huge closet' that is not designed to walk into is just gonna be a pain dealing with whatever is in the back.
Heat and AC is good, but not 'into' each space. AC brings condensation and possible nasties into a warm environment, designed to grow stuff. So having the intake in a ROOM that has climate control is better. If you end up in a garage, you could still have it on a wall that connects to the house, and just cut a return air vent and mount a grill inside the house. Nothing suspicious OR ugly about it. But in my case, a closet in a climate controlled bedroom is the same thing.
Raise the floor and make it waterproof. No matter what else this is just handy, but you can also rig a drainage system in the sub-floor, flush plants in place etc. if you really get into it.
I'll let you know if I think of anything else, but basically look at how a tent is designed, and do that
https://www.amazon.com/BloomGrow-Reflective-Hydroponic-Water-Resistant-Removable/dp/B076JDB8ZG/ref=sr_1_12?crid=1NXD1T69NZKG7&keywords=veg+and+flower+grow+tent&qid=1548109357&rnid=2941120011&s=Garden+&+Outdoor&sprefix=tent+flower+and+veg,aps,219&sr=1-12&th=1