"letting the shower run for 30 minutes...no leaks" That showed no evidence of water flowing during the 30 minutes. The mushrooms? That shows you have a wet curb. How the curb got wet is the mystery. You mentioned "going under the house." Is this a crawl space? What is the "ground" of the crawl space? Dirt? A thin rat slab? A membrane of some sort over the earth, with the membrane covered by stone or something else? If there is any membrane, how is it detailed, or sealed, to the perimeter walls of the crawl space, or is this open pier and beam construction. You mentioned "in the crawl space you can't see anything because icynene is sprayed under the house...". Here's a concern. Crawl spaces are moist. Thus the need for vapor barriers of some sort to protect the underside of the house from excessive moisture/humidity build up in the crawl space. If there is a vapor barrier, it needs to be properly sealed against the mudsill (or some other part of the foundation's perimeter) of the house. That prevents any damp air from beneatht eh vapor barrier from getting to the bottom of your first floor. Back to the icynene. Icynene is an OPEN CELL foam. Meaning, it's like a sponge. A particle of air, on a microscopic level, could pass right through a thickness of icynene. On the bad siade, moist air can pass into and/or through icynene, and the icynene can hold the vapor from the moist air, with the foam eventually becoming saturated. Not "saturated" as a spnge, where water will drip out of the pores, but "saturated" in terms of the foam holding moisture against the bottom of your house's subfloor. If Icynene is to be used in an application like this, is need to be sealed with a topical sealer that will serve as a vapor barrier, that prevent the open-cell icynene from becoming saturated and promoting rot. A better foam is a closed-cell type of foam like polyisocyanurate, or "polyiso". While not technically correct, think of polyiso as being a bunch of microscopic sealed spheres. Air can't pass from one, through one, or around one sphere to another, so polyiso is "closed cell" and does not allow air or wate vapor to pass through it. Polyiso in and of itself is a vapor barrier. It does not need a topical coating to seal it. So...could there be a leak in the shower that is saturating the curb, that is in turn manifesting itself as mushrooms growing through the one unsealed area between the curb and the floor? Yes. Or could the icynene under the house be saturated and holding moisture against the bottom of your house's subfloor...and it's showing itself by coming into the living space through an unsealed area at the curb? Possibly. You have a history of the leak in the shower iteslf. That's a smoking gun. Your tile guy apparently wasn't the greatest. You have evidence of moisture outside the shower with the darker colored marble. those are a couple more bullets loaded in the already smoking gun. You have icynene under the shower. That can hold moisture, either vapor coming through the foam from the crawl space below, or liquid water soaking the fowm from a leak in the shower above. My first reaction is that at a minimum the curb needs to be demo'd, as that's the source of the 'shrooms, and the area under the curb needs to be dried out and repaired. Depending on the extent of the damage, it my then be prudent to go under the house and cut out a small section of foam to expose the area of subfloor unde the curb. Start small, as you may find no damage at all. From there, you'll have visual access to the damaged area from above as well as from below. It'll be like peeling back the layers on an onion. Go only as far as you need to, for like cutting into an onion, the further you cut into your house, the more it'll make you cry. Regardless, check out the combo of the crawl space and the icynene. Make sure you have proper detailing of botht he crawl space and the underside of the open cell icynene. Sorry for the long post...but moisture damage can be insidious, and the combo of crawlspace and open cell foam made me want to reply with a little more detail than I might otherwise offer. It might just simply be a bad shower, or it might be more. But you just need to have your eyes wide open so you can actually process what you see when you try to make repairs to the damage that you have. Mongo

Thanks, Jack. I had a Noritz tankless at my old house and am familiar with the placement implications. The new one is a Rheem (re-branded Paloma) and is has lower initial activation and continuous flow sense requirements than any of the others. That was one of the few complaints I had with the Noritz (no hot water with very low demand fixtures operating alone). The unit's inlet and outlet are 3/4" and the supply trunks that connect to the current tank (not far away) are as well. No sense in deviating for less than 10 feet of path. I already know the local gas utility needs to upgrade the meter to handle my simultaneous demand (199k BTUh for the tankless alone...), but I believe the distance and diameter of the black iron already serving the vicinity of the install will be adequate. BUT...maybe not. That's why I'm hiring a pro to calculate and warranty that part. Also, the gas company won't even touch the work until after it's permitted and signed-off by a licensed plumber (fair enough). I was thinking of a 3/4" board large enough for all the mounting of what's pictured in the attached image. I have a combined tpr valve outlet on my (hot) service valve, but everything else should be nearly identical to that image. My current tpr outlet is actually slightly higher than the new heater will be installed, so I may have to re-route that to a floor sump a few feet away instead. Also, I plan on hard-wiring mine to a box with a power switch and an accessory receptacle. Not sure if I need the hard-wired portion to be GFCIed or just the receptacle.

Here's some more pictures of the bracing. As you can see the weather is better today so I was able to work. Tonight after the kids go to bed I'll seal the ends of the panels with caulk so they can cure. This is the side wall where the corner braces and side wall braces connect. They are anchored at the top of three center most studs. Showing where the ones connect on the back wall And a closer view on the back wall. Bracing this wall is mandatory as far as I can tell. Far too much give in it as designed. This thing is rock solid now. Its going to take some major wind to hurt it. I'm a huge fan of this green house and the design (for the most part). The track design to hold the bolts makes adding stuff down the road super easy. I'm already thinking of adding bolts to let me attach shade cloth to the inside of the roof. Grommets in the shade cloth and fender washers would allow you to attach the cloth right to the ceiling snugly. The back wall at the peak is just begging for a fan too. I won't caulk the panels in so I can take them out to add things to the structure as needed. Oh the options are endless!!!!!!!

What I hear you asking is, Which structural items should be splurges? You'll find lots of opinions on that, but my thoughts: - Go with 2x6 framing ... it'll "feel" more solid, and you can never go back and build your exterior more solidly. - Go with a simple roofline ... a simple roofline is cheaper, yes, but also a simple roofline gives fewer weak points for leaks to begin. I am going with a metal roof, which is more expensive up front, but I will probably never need to replace it in my lifetime. - Windows are a splurge item. I've spent lots of time staring at people's windows as I walk my dog, and I've decided that windows are a make-or-break item. Quality windows do so much for the look of a house ... and they also save you money on your utility bills. - Splurge on quality doors too. Not necessarily fancy doors, but solid doors that'll keep out an intruder. - Since you want the option of expanding your attic, be sure that you build your attic flooring strong enough that it can be living area. This will cost you up front, but it would cost much, much more in the future. - Go with mid-range, standard sized appliances, HVAC, etc. Maybe that's not a structural item ... I'm not sure. - Go with upgraded electrical and extra outlets. Likewise, try to consolidate your plumbing (that is, back your kitchen up to your bathroom so that fewer walls are water-carrying walls) and go with the best quality plumbing. Take photographs of all these things while your walls are still "open". - I'm going to disagree with you on one item: We're planning to build on a slab. Why? Because we had a repairman out for our HVAC last month, and my husband dutifully walked him to the crawl space. He came back into the house without the repairman, and I guess I looked surprised. My husband said, "I am 53 years old, and I am never crawling under the house again." (Note: He has always despised crawling under the house or going up a ladder onto the roof.) I said, "Okay, then that decides one of our construction queries. If you're never going under the house, we're building on a slab." He just nodded, and walked away. Decision was made. Just be aware that if you spend the money to build it above basic standards, you will never recoup that money when you sell the home someday. No one will pay you for that. We are going mid-range on just about everything. For most things, I think that's "plenty" and is the best bang for the buck. Use a quality house wrap, better yet use the Huber Zip System or at the very least a rainscreen system for your siding. Make sure your windows and doors are flashed properly (including a sill pan), and installed perfectly. Less visible than the framing, but -- yes -- very important. Similar thought: Don't skimp on insulation. (ICF if you're expecting small arms fire in a coming civil war.) You laugh, but we have two firing ranges on our farm. One for guns, one for bows and arrows. AND we have a significant problem with trespassers coming on our land to deer hunt ... worse, these jerks take the heads and feet and leave the bodies behind for us to deal with. Flooding is usually not an issue, although Hurricane Matthew this past October dumped a lot of rain and caused flooding that's never been seen before in this area. I'm in your general vicinity, and -- yeah -- we don't need to think about some of these extreme weather needs. I've seen flooding after a hurricane a couple times, but it's not common. I was living in the Charlotte area during Hurricane Hugo, and Hurricane Floyd was not kind to us. But, honestly, we don't have some of the issues that other people have in more extreme climates.