After making a lot of calls all day and talking to practically every inspector and builder in our builder's association, I have come to the conclusion that I just happen to find something that likely happens in every winter build. I reacted a bit hastily and tore our about half the house to dry out the bays and fg. I'm coming off a week of paying and arm and a leg for a basement remediation company to encapsulate our crawler, so I think I was just a bit paranoid about ANY moisture. Thank you for the link Renovator8! I had read a few other articles that guy has written and he makes a lot of sense. I definitely fall into the old school category. I have some major concerns about sacrificing the health of your structure simply in the name of energy efficiency. I just don't think having an energy efficient home should trump all else requiring expensive air exchange systems to fight what a well designed and considered home is capable of doing on it's own. Every mold mitigation company rep I spoke to today says they only really see mold issues in homes that are way too tight, and most importantly ones that have vapor barriers in the ceiling. Virgilcarter- Every house I have worked on in Montana or Wyoming has basically the same insulation design. Usually about R20 batts, OSB sheathing (plywood only on really high end stuff sometimes), and Tyvek wrap. Usually no vapor barrior inside if using faced batts. Only one guy today has heard of anyone ever using rigid foam on the exterior and that was in a town on the other side of the mountain two hours away that has horrendous and constant wind, and not in an area known for their quality builds. worthy-I too have the same question as rollie? Where do you get your sheer from? Are you putting an additional sheathing over the XPS? What do you do around the windows? Envisioning and inch or two of XPS then sheathing...would I have to use a 6" screw to hold my 2" window trim? Or bucking out your window to sit flush with the exterior?

Inspector was never on the job. It was pretty self explanatory. Thousands of wrong nails were used. Huge liability.rust belt. Builder knew it was wrong and is doing the right thing. And he has gained my respect back. Thank. This post was edited by jasburrito on Sat, Aug 23, 14 at 1:00

@T Burns I don't have an ATMOX system, but from what I've seen they have one inside and one outside sensor input on their controls. One outdoor should be sufficient, but for a large crawlspace I'd prefer more than one just because humidity CAN be localized if there is bulk water such as a flood or plumbing leak. My home had mold and rot only in certain areas--generally the east (downwind) side. The ATMOX optional louvers don't appear air-tight but passively flap down over the opening when the fan isn't running, like on a dryer vent. It's probably no worse than a typical sliding crawlspace vent. Plotting temp and RH over time is a great idea. From there you can obtain dew point and get an idea how often an ATMOX system would be able to run with just fans to keep the RH below 60%. With tight clearance between floor framing and the ground, the joists will track ground temperature by radiant heat exchange unless you have lots of airflow. You can get an idea of what RH will be at the joist surfaces by looking at those temperatures and figure out what max average dew point should be allowed. From there you can look at historical dew points for your area and get an idea of what percentage of the time fans can actually dry the crawlspace. As the ATMOX folks point out in their literature, it takes an extended problem to elevate wood moisture content enough to cause mold. You may be able to get by with a dehumidifier for half the year or less. But I would definitely not install one of these systems without a dehumidifier as backup, integrated into the control logic. If nothing else, it will come in handy if you get a flood or a fan goes bad and you need brute force drying. There might be some aspects of encapsulation that could benefit your situation, but I'm leery about arbitrarily introducing spray foam, foam board, or plastic-wrapped batts, like the Youtube encapsulation guys do, without really thinking through the moisture transport situation. You could easily end up trapping moisture or hiding rot or termite activity in an old house that wasn't built to modern codes. For example, my home has poly flashing between the rim & band joists and the brick, lacks a brick ledge, and was not built with pressure treated sills. If the brick really gets soaked, the framing gets damp. This is a once-a-year event at most, but it has a way to dry. The last thing I'd want to do is to trap moisture in the lumber. Also, my home's crawlspace vents also admit air to the gap between the brick and sheathing, and blocking those gaps with foam board will reduce ventilation behind the brick. Retrofitting an older home has to be taken case-by-case. I wouldn't trust most one-size-fits-all encapsulation contractors to consider that. I would probably never be totally satisfied with an ATMOX system, since the control logic isn't arbitrarily customizable, but it's an incremental improvement over full-time passive ventilation that we know doesn't work in summer. Automating the ventilation and combining occasional dehumidifier use may be all you need to banish the mold if there are no drainage issues. Thanks for the tip about the upcoming revision. I'll have to get in touch with them to see if they're adding fan diagnostics.

Seble, we have had multiple things done which helped with it and it seems to have gotten better. They switched out our HVAC unit to a smaller one (turns out our upstairs unit was 1 ton too large so it was short cycling and not removing enough humidity inside). They also insulated an unfinished bonus room upstairs that connected to the hall bathroom where our biggest issue was. And they also foam insulated around outlets, bathroom vent fans, etc. It sounds like you have a bigger issue since your mold is behind the walls and ours was surface mold only. We have a slight smell still up in the loft where we have the built-in desk/bookshelves, but they came out and did some more insulating a few weeks ago. So, I’m hoping that that’ll resolve the issue permanently. This is our 3rd summer in the house and so, we’ve dealt with many troubleshooting session with the builder and his various subcontractors. We had a structural engineer come out and do a full inspection too. You might have to do the same. It’s very frustrating, and I’m not even sure we are 100% out of the issue. Just praying we are. It seems like it is a multi-factorial issue and every change has made some improvements, but there wasn’t a single fix.