Rigid foam: Shrinkage? Creep? Taping and foaming seams?
So I was prompted to post this as a separate thread….
I’m in the middle of building a zero-energy home and barn. I’m using LOTS of EPS reclaimed foam on the exterior. To be exact….
The barn gets:
2 layers of 2.75″ on the walls & 5 layers of 2.75″ on the roof
and on the house:
3 layers of 2.75″ on the walls & 6 layers of 2.75″ on the roof…
Like I said, “LOTS”!
I’ve hemmed & hawed for literally hundreds of hours about insulation for my project, considering nearly every material – well except pink fiberglass batt insulation (I was beaten with it as a kid!), and researched and dug up material on virtually every way insulation strategy. I settled on PERSIST and or the REMOTE technique – check out CCHRC.org for more info – it is a fantastic solution.
Ultimately I wanted to be foam free, as my project is fossil fuel free too, but the price for the reclaimed EPS insulation was simply just too good to pass up. Plus, I wanted to build a REMOTE house too, and they used EPS, so it was a perfect fit. I found the reclaimed EPS I’m using from what was InsulationDepot.com and is now Nationwide Insulation. It is in really remarkable condition.
Since deciding on my insulating technique, my neighbors have thought I was going into the styrofoam insulating business because we have five tractor trailer loads of EPS on the jobsite. I’ve had several many discussions with folks and have read as much as humanly possible it seems on the best building practices. I even took classes from renowned folks on insulation, several in fact. There was one specific class, with one set of instructors whom I had some very passionate conversations about this strategy I had chosen, and the strategies they liked (cellulose primarily). Great folks…I REALLY love a passionate type.
The root of problem was (in their eyes) that I had not decided to tape and foam every seam, on both the walls and roof. Now I’ve tried to read nearly every study about exterior insulation strategies and many weren’t advocating for any/just one/ or both tape and foam at the seams. These guys were, and it kinda threw me for a loop…it was a lively conversation. The conversation was about how no matter how many layers you put on, you’re going to have creep (not from gravity, but from shrinkage), whether the shrinkage was caused from aging, or temperature. There would be creep and shrinkage on every layer, and I would be doomed if I don’t tape and foam.
I had spent a good bit of money on this mutli-day class and they were telling me what so many others weren’t. I was again frustrated. Even though the manufacturers and a few scientists stated that foams do shrink (but most of that was initial aging, and if temperature based – not multi-layered), they (the scientists) were recommending it for general project use.
So after this long, drawn out post – what is the word on the street? I was going to both tape and foam my seams – is it excessive (I already know that the amount of exterior foam is “excessive”)? Do we really need to do foaming at the seams, everywhere (cracks, holes, broken corners – sure)? Do we really need to tape every seam on every layer? Should it be done on just one thinner layer or two, or even when you are putting it on multi-layered and thick?
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