Has anyone got any experience - good or bad w something like versi- foam DIY kits. I would like to spray in a 1-2" flash and then put in an R15 batt (2x6 walls). I have a quote from a pro but to do the walls and roof deck it was $25000 for a 3000sq ft house vs 84 lumber doing a R21 fiberglass and caulk pkg at $9000. I WANT SPRAY FOAM BUT i'M NOT PAYING THAT KIND OF A PREMIUM.

Wow that quote sounds high. I'm also building a new house (2325 sq ft) and having Icynene spray foam put in. They are only spraying the rim joists and entire living envelope. Includes 2x6 walls (depth 5.25" nominal fill) and two cathedral ceilings (depth at 6" nominal fill) for a total of 19,400 Board feet for $9000. I'm putting blanket insulation in the basement and batts in the garage to save some money. To spray both would add $5700.

I should also add I will be doing 1" xps sheating on the exterior at R5 ( (2) 1/2" layers w/ seams offset)

I must live in a higher-rent neighborhood than Alton! :-) In my area 2lb closed cell goes for more like $1.15-1.25/board-foot, depending on the size of the job. Half-pound open cell is more in the $.040-0.50/board-foot range.

The DIY 600board-foot 2lb foam kits like Versi-foam/Tiger-Foam etc run about $1-1.25/board-foot + shipping (as much or more for just the material than it installed costs to let a pro do it.) Haven't priced it in the drums, bu tyou could spend a lot of money and end up with a low-performing hack job- there's a reason the pros use expensive tightly temperature controlled spray systems: It uses less chemical and delivers consistent results. I'd only consider using the DIY kits for things like pickup-truck beds, air-sealing jobs, or boats, etc.

Flash & batt is good, but flash & wet-spray cellulose (or blown fiberglass/cellulose) performs better, since perfection installation is impossible with batts, whereas sprayed/blown insulations conform to all surfaces and fill all voids large & small with ease. Dense-packed wet spray cellulose by itself can be a near air-barrier, not quite as tight as half-pound foam, but almost. Price/performance dense packed spray cellulose often the best value, but if you're looking for vapor retardency and a perfect air-barrier there's no substitute for 2lb foam. With densed-packed spray/blown cavity insulation you get lower convection loops within the wall cavity than with batts along with fewer gaps and voids, whether you flash-foam or not.

With staggered seam XPS on the exterior and air-tight construction methods on the inside you may well be better off with dense-packed cellulose- there is such a thing as "tight 'nuff". Whether & where you add a vapor retarder depends on your zip code/climate.

If you need or want more R-value and an interior vapor retarder, 1/2 or 3/4 inch taped seam foil-faced iso on the interior under the gypsum (staggering the gypsum & iso seams) can be effective, increasing your thermal break at the studs from about R5 (the exterior XPS) to R10 (exterior XPS + interior ISO). Depending on the specified thickness of the flash-foam, dense-packed cellulose w/interior iso may well exceed the whole-wall R-value of the flash & batt approach. The higher you go with the R-value of the cavity fill, the more the thermal bridging of the stud dominates the heat transfer. At some point more thermal break becomes cheaper & better than better cavity-fill. IIRC, comparing half-pound foam cavity fill + 3/4" of iso vs. 2lb foam fill & no thermal break in a 2x6 16" o.c. wall, the half-pound foam + iso wins on whole-wall R value by doubling the R-value at the studs. (With exterior XPS & interior iso you'd be tripling the R-value at the studs.)

Thanks for the very informative help. I am in Michigan so Alabama may be a haul.

Dana- my one concern about wet blown cellulose is mold- should this be a concern?

All cellulose products contain chemical mold inhibitors, but any wet-spray application is best allowed to dry before putting up the interior gypsum.  A day or two for 2x4 construction, twice that for 2x6. Depends on the temperature & relative humidity during the drying period- in Arizona mid-summer you probably can button it up same-day, on the gulf-coast you might need a week, even in summer.  Wet-sprayed in MI in summer should be fine, but probably not in December.  If you're planning to use an interior vapor retarder (or vapor retardent paint), give it at least a week, or even a month before putting the vapor retarder up, but it'll continue to dry through un-painted sheet-rock just fine (sheet rock is highly moisture permeable), so if the paint can wait, it should.  If the equipment is set up correctly the amount of water in the spray is very small- just enough to activate the adhesive- the amount of trapped moisture would be small, but if you close it up too soon with an interior vapor retarder it'll be next summer before it really dries through the OSB/plywood + XPS.  Frost forming in the insulation will compact it some, even if the mold risk is still near-zero (it won't be destroyed, but it's just better if you don't let that happen. It'll still be outperforming batts.)

If you're still concerned, you can dry-blow dense pack it. (Be sure to specify borate-only, sulfate-free fire retardents, as I was just reminded on another thread.)  In this instance you'd be putting up the interior gypsum and caulking/sealing before the exterior XPS goes up, drill the structural sheathing for dense-packing (one hole method) from the outside, air seal the drill holes (purists will use lo-rise sealing foam), then apply XPS sheathing.  You can drill through any housewraps/felt etc. as long a seal it afterword.

Dense-packed cellulose in a 2x6 wall is good for R20-20.5, but R20 blown will outperform R21 batts every time due to the tight fit and lower internal cavity convection.  Sprayed or blown-in-netting from the inside is still better though, since framing cavities less than 3" wide can easily be missed when you can't see 'em, and cavities less than 1.5" simply can't be dense-packed in a closed cavity the way they can when it's open (the same problems as stuffing micro-cavities with cut batting- a 1/4" gap is labor intensive or impossible unless foamed or sprayed. If you go the dry-blow dense-pack route, foam all the micro-cavities from the inside before you close it up. (A 100-board-foot FrothPack kit or similar would probably be more than enough.)   Then marking or pre-drilling any of the smaller cavities prior to closing it up would ensure they're not missed.

Another great recommendation made by Jesse Thompson on another thread:  If you install the exterior sheathing & all the doors & windows prior to insulating  then run a blower-door test and scurry around foam/caulk sealing all the air leaks you can dramatically decrease the air-infiltration from the outside.  Then if you repeat the process after the wallboard is up, (but before painting/cabinets etc are installed) you can get AMAZING tightness to  the envelope without resorting to an all-2lb foam house.  (Many ways to skin that air-infiltration cat, eh?)

chewyspartan, take another look at increasing the depth of your exterior rigid instead of spray foam. Your labor is the same for 4" of rigid vs. (2) 1/2" sheets, less if you get the 4" in a single slab.

Your window and door details change a bit, but not that much. Building Science has extensive documentation for those details.

That thermally broken exterior rigid will do more for you than 4" of closed cell in the stud bays ever could.