A couple of thought: First, having just gone thru designing and building an engineered GH, I doubt your conduit on 4' centers will hold 52#/sqft load. My place is also 15' wide. I use 14ga 2" sq steel tubing on 4' centers, and that would not meet our 48# load. I ended up needing a center support (a small I beam) running the length at the midpoint of the span, with posts to ground to take the extra load. So I doubt the smaller, thinner conduit will be able to do it without some mid span supports. The steep slope of your roof might help (I don't recall the amount of load shedding that gives), but if you really want the structure to be able to hold 52# per sq ft, I don't think this will do it. You could look into building the "arches" into trusses (more so than you are already doing), by adding strategic cross members. That would certainly up the load they can handle but I can't say that alone would get you to 52#. Of course, if you are willing to go out there and brush the snow off after every big storm, it may not matter. BTW, does your 52# load include wind loading? I am curious why you plan to run the length of the GH N-S vs E-W. Typically for maximum solar gain in fal/spring/winter one aligns them E-W. I'd agree with the other comments about vent size. You might consider vents on the ends close to the peaks. Not entirely as good as peak roof venting, but much easier to build, and if the building is aligned with the prevailing breezes, can work OK. You might even consider removing the ends for the summer.

Interesting conversation. Although the first video was scary to watch, I watched it again and did notice the first house wasn't even completed which to me leads to the interview to be inconclusive. You can't compare a finished home to a new home under construction with just wood framing and then say the new home burned down, it just doesn't make sense or maybe I overlooked something. I don't have my house covered except for windows and roof but I do know it would burn down faster than my neighbours house which is 60+ years old because my home is essentially *naked* and I would have nothing left if both our homes were to have a fire. As for insurance, my insurance company hasn't asked anything about our trusses vs. traditional lumber so my premiums would remain the same. I was pretty concerned about this whole thing after reading it yesterday and called our city inspector (who's also a friend) and asked about the pros/cons and his response was "if new homes have this problem which he hadn't heard of, older homes have others you may not have such as old electrical issues so there's concerns about everything causing a fire in any type of home". Not trying to argue with anyone but essentially everything in our homes are a fire hazard that can bring down a house in a matter of minutes. As long as everyone is out safely, that's what we all have insurance for.

Hi, Bill I was not sure if I should start new thread or not since its same subject/ similar situation, I want to use a white glass over porcelain tile it is a very strong thick tile that is 24 x 24. (have you seen it/use it before?) I have wood truss (2nd floor) framing with varying spaces from 16" to 24". Probably only the shower area they ran them closer the rest of the room is 24 We have 2 layers of 3/4" plywood down and we are going to run screws every 4-6 inches or so to reduce movement. I was then planning to use the orange ditra with the little squares to eliminate the possibility of cracking. Am I correct? Old floor was 6 x 6 bathroom ceramic wall tile and it was a mess with cracks. I don't want a repeat performance. I thank you in advance for your help.

I was forced into renovating a second floor bathroom for numerous reasons. Never having liked the layout, I thought this was a perfect time to change it. The room is 70" wide by 126" deep. I wanted to put the vanity on the left wall, the toilet next to the vanity and then the tub on the back wall, drain to the left, so the left wall would become a wet wall. Problem was, the joists ran across the room, not down. Putting the toilet on the left wall would force me to bore 4" holes through 2"x8" joists. The two joists to be bored would sit directly under the tub. A real no-no. I did a little (clearly, not enough) research on the internet & mostly talked to some local building supply stores. I had an idea that laminating (glued & screwed) 7 1/2" X 30" strips of 3/4" plywood to both sides of the joists might provide enough support that the joists could then be bored. And this is where I was ill-advised. I was assured this would provide enough support, and that with 3/4" ply subfloor followed by 1/2" cement board the floor would be solid enough to support the tile I wanted to install. After completing this portion of the renovation and replacing the subfloor, another trusted advisor spoke up and said that I can't do that. I've since stopped the renovation in order to take the time to figure out what to do so that the plumbing and floor support will be safe and to code; hence, my now having found this thread. As an FYI, in doing my second round of research, I stumbled across these metal joist reinforcers - http://www.metwood.com/products/reinforcer . They look like just the thing I need to solve my support issues, assuming I leave the bathroom in it's current configuration. The problem with them for me is that they cradle the bottom of the joist and I don't want to have to tear up the first floor ceiling in order to install them. So, one of my questions for all you engineering gurus with your mathematical wizardry is, if I were to attach 30" long strips of 1/8" or 3/16" steel strap to both sides of the joists, both above and below the holes, do you think this would provide enough support for a full tub of water and a tile floor? If so, how would you suggest fastening them? Should they be screwed independently to each side, or bolted so that they sandwich the existing laminated joists? Further, should I be using some form of glue or cement to 'laminate' the strapping to the bulked up joists (not that I'm aware of any metal-to-wood adhesive)? Another option I have is to remove one side of the plywood lamination I've done. Then sister both existing joists with a new (at least 6', but as long as possible) joist that has one of the joist reinforcers listed above attached. Due to the construction, the joists are fully supported by a bearing wall on the left side of the washroom so these new sistered joists would have the benefit of being supported on one end. Any thoughts on any of these potential solutions? Thanks in advance for anything shared.