Yetti Finishing??

[randerson]

I'm wondering if spray foaming over the foam board on a shell after firing out and doing all the wiring would make since. Just thinking it would firm things up a bit and help the insulate a bit without warping the siding from direct sprayfoam. Any reason not to do this? Thanks in advance

[YettiStyle]

Would be a possible idea.  I'm in the process of finishing off mine right now (thanks to El Nino I have a little extra time).  Is what I did is fur out with 2x1" and use 3/4" foam board between the furring strips.  The gives me about almost 3 inches of insulation and an R-value of at least 14ish.  I think the biggest problem with going with the spray foam on top of the rigid insulation is the depth, or lack there of, of the cavity the spray foam will be.  In order to create a true vapor barrier, there needs to be at least 1" of spray foam.  If you wire your shack first and then spray on top of the wires then you might have a mess on your hands if you ever want to replace or add wiring later.  3/4" of spray foam isn't going to give you as much rigidity as you might think compared to even an inch - let alone 2"+ that normal shacks have. 

 

For simplicity, ease of installing, and for future additions/replacements, I would just go with installing rigid insulation.  You aren't going to gain much (if anything) by going with the spray foam and the cons definitely aren't worth it in this situation in my opinion.  If you really want the benefits of spray foam you might as well take out the original foam Yetti installs and start from scratch. 

 

If you're installing the 5/16" cedar or pine T&G siding then you are definitely going to want to have something rigid behind all of that T&G.  The stuff is pretty thin and if you don't have anything directly behind the boards it is pretty easy to punch a hole right through it.  Here is what I used for the insulation http://www.menards.com/main/building-materials/insulation/insulation-panels/jm-ap-foil-trade-3-4x4x8-r-4-4-foil-faced-polyiso-rigid-foam-insulation/p-1444438921381-c-5779.htm?tid=377028547277812410

[FishinFools]

Layer 1, and 3/4" plywood furring strips.

layer 2.  

I decided that I was never going to achieve a true "vapor barrier" as I wanted to be able to (possibly) fix wiring, etc issues in the future).  It's aluminum, right?  

Will be out on Upper Red tomorrow for our first "on the ice" experience.  (Worked great during deer season!)

[Hawg]

It could be tough to put foam on that thin. I can't think of anyway to do it.