Bought cottage to fix for retirement. Central Ontario near Casino Rama. 24 x 24 frame wood clad cottage built in 50's and shed addition added for total of 24x 36' Cottage was raised in 2008-no poly or insulation under slab. 3 foot block wall on slab then 2x4 stick frame and cottage lowered. we have dug down and found 12" of coarse gravel and 12" of concrete slab on perimeter, coarse clean gravel extends out from the bottom of slab 24" So we have slab edge exposed, 3ft block wall exposed and then the 1/2 osb sheathing (covered in (vapour barrier and taped) above that and then the jut out of the existing wood siding. Interior insulation: none on slab floor or interior of blocks, fiberglass bats in 2x4 framing covered with plastic stapled on. Original cottage has 4 inches of loose fiberglass insulation in attic (can see light from below when up there!) and none in walls. Windows were replaced as they broke when the former owner had it raised. We will be finishing inside especially main floor which will be open concept kitchen, bath, dining, family room.Exterior will be vinyl siding. Any help would be appreciated. I tried to upload pics but may because I am a newbie?

Since you're re-siding the building, this would be a good time to apply insulation to the outside. This would provide you with a continuous layer of insulation and a way to completely thermal-break the structure.
Done, with foam, in two 2" layers would provide you with roughly R20, PLUS anything you decide to put into the wall cavities (spray foam, fiberglass/rockwool batts, blown-in, etc). You then lay down vertical 1-by furring strips to attach the siding to.
If you're going to re-roof, you can do the same thing up there.


Don't worry about uploading pictures. This forum is ALL sorts of messed up and broken.

As to the way foundation is. Lemme see if I have this straight.

You have a concrete slab.
You have essentially a concrete block "knee wall" on top of the slab.
You then have the actual cottage structure built on top of the concrete block, leaving a crawl space underneath?

You're just north of Toronto.
So you're a solid Climate Zone 6.  So the insulation values you need are fairly straightforward.

Attic: R49-60
Cathedral ceiling: R30-60
Wall Cavity: R13-21
Insulation Sheating: R3-6
Floor: R25-30

If you're doing insulation on the outside, as well as cavity fill, the walls should be easy.  The floor and the attic/roof area are what's gonna be tougher.

If you have someplace like Google or a website to share photos on, put them up there and just paste the URL into a post.  We can go there.

Also, important.  Are the rafters of this cottage ALSO 2x4?
And is the roof vented?

To hit IRC code min for 2x4 walls for zone 6 it would need R10 continuous insulation on the exterior, not R3-R6. With R10 on the exterior the interior vapor barrier could be removed, but that's not critical, and the wood sheathing would have ~100x more drying capacity toward the interior, and would not accumulate excessive wintertime moisture.

Finding a source for reclaimed roofing foam takes a substantial amount of the wallet-sting away. At 2" typical 2lb roofing polyiso is rated R11, and even though it will underperform that mark on the coldest hours of the coldest days, the average performance will be in the R4.5-R5/inch range, which is good enough from dew point control perspective. (I can typically find 2" reclaimed roofing polyiso for USD$10-12 per 4'x8' sheet, and have never paid more than $15.)

The wall foam can be initially cap-nailed in place, then strapped in place with 1x4 furring (not 1x3s- they're too twisty and split too easily) through screwed to the studs with 5" panCake head timber screws 24" o.c. (eg Fastenmaster HeadLok ), and the siding gets hung on the furring. The timber screws need to penetrate the studs by at least 1.5". With 1" or thinner foam it's sometimes possible to long-nail the siding to the sheathing (check with the siding manufacturer first), but with 2" it doesn't work.

Unless you're re-installing all the windows the window flashing is diveirting bulk water to the structural sheathing plane, which would be a problem if installing insulating sheathing. If installing exterior insulation it's worth installing a crinkle type housewrap (eg Tyvek DrainWrap) taking care to lap it correctly to the window flashing. Even a tiny amount of drain spaces provided by that type of housewrap allows gravity to manage the bulk water, and offers at least a modest amount of capillary break.

Do NOT insulate between the floor joists. It's nearly impossible to air seal a floor, and putting insulation under the floor becomes a freeze-up problem for both drains and potable water plumbing that pass through the crawl space. (Any ducts in there?) It's far better to air seal and insulate the foundation wall- R15 continuous insulation or R19s between none structural 2x6 would meet IRC minimums for zone 6. If installing insulating sheathing on the wood-sheathed wall above, installing an equal thickness of EPS on the bottom portion of the wall (or whatever thickness would make it roughly co-planar, if the sheathing isn't currently aligned with the exterior of the block wall) makes sense. Install the EPS first, and use EPDM flashing tape to create Z-flashing that laps correctly with the housewrap to direct moisture outward at the seam where the insulation above meets the EPS. The EPS can be cap-screwed to the block wall, then finished with a cementicious hard stucco-like material such as Quikrete Foam Coating or similar once the Z-flashing is in place. If the block wall's exterior EPS is 2" thick it's alreay half way to the code-min R15 on the exterior, and adding a non-structural 2x4 wall on the interior side of the wall insulated with unfaced batts (and no vapor barrier) would be more than sufficient.

If possible, insulating the slab edge down to at least 2' (4' would be better with) 2-3" EPS would thermally break the path from the outdoors to the slab. If it's not possible to dig that deep, do what you can- even a foot of slab edge insulation makes a difference. If it's shallow, adding horizontal foam extending outward from the wall foam also makes a difference. There is no need to insulate the top of the slab, but vapor sealing it with an epoxy finish would be in order if it seems humid in there. Caulk any cracks or seams in the slab with self-leveling polyurethane caulk, even if you don't install a vapor sealing finish. It's fine to leave the vapor barrier on the block walls if there is at least R8 on the exterior, and no more than R15 on your interior side studwall.

It's unlikely you have sufficient vertical space to get to an IRC code minimum R49 all the way out to over the top plates of the studwalls, but how deep ARE your rafters and ceiling joists?

http://s1320.photobucket.com/user/asiquis/library/?view=recent&page=1
Wow! Thanks you so much! Pictures may help, no chuckling at the "beast"
Cottage is hip roof on original 24 x 24 cottage with 10' 8" shed addition on lake side.
First floor will be finished open concept so need wall insulation with framing on blocks!
4 bedrooms upstairs and small washroom.
"advisor" says 1x 3 strapping 24" OC and put 3/4" xps insulation outside no waterproofing or vapour barrier needed and no insulation on slab floor-hence my query since it seemed "underkill"
Also says don't worry about insulation on the shed roof and yes. roof needs to be replaced.

Okay. Those pictures help.

Eek! Ground level is a half and half wall of concrete under stick.
You have 3 realistic options insulation there without getting stupid on the exterior sheathing or requiring major restructuring work.

1: Build "knee" walls, spaced slightly back from the concrete. Go whole hog with vapor barrier, etc. and then insulate the knee wall and cavity (STILL USE insulation sheating outside!) You then wind up with a "bench" around the entire perimeter of the room.

2: Same as 1, just make it into full floor-to-ceiling double-wall construction. Recommend offset stud wall to minimize through-wall thermal breaks. Rebox the windows. You then wind up with a wall 8-1/2 to 10" deep and perfectly suited for blown-in options like cellulose. (Again, still sheath the outside!)

3: Interior foam board and furring strips on the inside with cavity fill of whatever you're going to use. (As always, sheath the outside.)

Reinsulation of that concrete pad floor could be tough. Or expensive. If you just throw a couple inches of foam board down, you basically turn that bottom stair step into a tripping hazard.
If you turn that bottom treat into your new floor height... Your entry doors are going to have to be restructured or given small "mud floors" with a step up. The ceiling might be a bit...tight at that point.

I can see that the property is in desperate need of re-grading. While that sucks from a pocketbook standpoint, it's good as the requisite digging allows you to dig down around the foundation/slab to extend your sheating down as Dana suggested.

I'll probably see more another time. But right now it's late, I've had a LONG day, and whatever I'm using for a brain is screaming for sleep.

Continuous interior side foam + exterior side vapor barrier (or exterior side foam) = moisture trap. DON'T DO IT!

At any thickness foil faced foam is a true vapor barrier, with as little as 1.25" XPS is sufficiently low permeance to meet the NBC definition of "vapour barrier", and unfaced Type-II EPS meets that definition at 3.5".

If furring out the pony-wall studs to match the depth of the CMU (or interior side foam on the CMU) doing it with "Bonfiglioli strips" will improve the thermal performance of the assembly, without reducing the drying capacity of the wall the way continuous foam will:

https://www.finehomebuilding.com/membership/pdf/9750/021250059.pdf

If the center cavity R increases, the R value exterior to the structural sheathing needed for dew point control at the sheathing goes up. Following the IRC prescriptives for zone 6 at least 35% of the total R would have to be on the exterior:

https://up.codes/viewer/wyoming/irc-2015/chapter/7/wall-covering#R702.7.1

https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing

So while R10 has margin on a 2x4/R13 wall, it doesn't quite if the depth of fiber insulation increases to 5.5" or higher. If you're going to cheat the ratio it will need an interior side vapor retarder. Because of the potential moisture trap problem it's better to use a "smart" vapor retarder such as 2-mil nylon (eg Certianteed MemBrain: https://www.certainteed.com/resources/30-26-074.pdf ), which satisfies the NBC definition when the air inside the wall cavity is dry (which it will be in winter, since the moisture will adsorb into the sheathing), but becomes vapor open at humidity levels sufficient to support mold growth, allowing the assembly to dry toward the interior in the spring as the sheathing unloads it's wintertime moisture uptake. The low vapor permeance during cold weather limits the total moisture burden to tolerable levels, and the higher vapor permenace as the weather warms up allows it to dry 50-100x quicker than it ever could through 4 or 6 mil polyethylene.

It's fine to use foam on both sides of the CMU- concrete can take it. If there is NOT a good capillary break between the bottom plate of the pony wall such as an EPDM sill gasket, heavy polyethylene, or metal flashing it's good to give the CMU at least some drying capacity, lest it wick moisture up to the sill plate. With 2" of EPS on the exterior finished with a CEMENTICIOUS finish on the exterior it would still be about 1.5x as vapor permeable as the NBC definition. (Plastic hard finishes for EPS can be too vapor retardent.) Any interior side foam on the CMU would then best be unfaced EPS as well, with no sheet polyethylene or other highly vapor retardent layers in the stackup of that portion of the wall.

If there is an adequate capillary break it's fine to use foil-faced polyiso on the interior side to minimize the total wall thickness. With EPS + EPS it takes about 4" total to hit IRC code minimum (2" outside/2" inside or 3" outside/ 1" inside, which would be better from a drying point of view). If EPS exterior/ polyiso interior the interior side foam can be about 1/3 thinner.

It will never be financially rational on an energy use basis to insulate over the top of the slab, but even a half inch of EPS and a 1/2" subfloor would help wintertime barefoot comfort issues, but it complicates all of the door & stair transitions. Exterior side SLAB EDGE insulation would be worth it on a long term financial basis, and would keep the edges of the slab from being substantially colder than the middle.

Posted By asiquis on 04 Oct 2018 12:27 AM
http://s1320.photobucket.com/user/asiquis/library/?view=recent&page=1
Wow! Thanks you so much! Pictures may help, no chuckling at the "beast"
Cottage is hip roof on original 24 x 24 cottage with 10' 8" shed addition on lake side.
First floor will be finished open concept so need wall insulation with framing on blocks!
4 bedrooms upstairs and small washroom.
"advisor" says 1x 3 strapping 24" OC and put 3/4" xps insulation outside no waterproofing or vapour barrier needed and no insulation on slab floor-hence my query since it seemed "underkill"
Also says don't worry about insulation on the shed roof and yes. roof needs to be replaced.

Time to get a new "advisor"- seriously!

At 3/4" XPS (about R3.8 now, R3.4 or less after 20 years) is nowhere near adequate for dew point control at the sheathing, and it absolutely WOULD need an interior side vapor retarder (or true vapor barrier). It would also be a code violation under the NBC if there were no interior side vapor barrier.

https://www.greenbuildingadvisor.com/question/poly-and-canadian-building-codes

Per Malcolm Taylor (a well regarded architect in Victoria B.C.):

"The code anticipates the use of exterior foam as a vapour barrier and requires that the inner-surface of the foam meet the requirements of maintaining a condensation free temperature or the assembly is required to include another vapour barrier closer to the interior. ((9.25.5.1 Appendix A (thermal Insulation)."

So with skimpy foam on the exterior then NBC (and Ontario) code requires there MUST include another interior side vapor barrier. Or perhaps your "advisor" is counting on the fact that 3/4" XPS falls just outside of the NBC definition of a vapour barrier(?), which isn't exactly a confidence builder.

At 3/4" unfaced XPS is sufficiently permeable that it would not constitute a serious moisture trap even with 6 mil poly vapor barrier on the interior, but at 1" it's getting dangerously close, and the consequences any errors in bulk moisture handling details become magnified. Without the interior side vapor retarder the sheathing will be at higher risk.

Your help is appreciated. Got a new builder. He is struggling with how to proceed. We essentially have 3 depths of exterior 1) deepest layer is the exterior 8 ft of the original cottage with the wood siding and no insulation in walls 2) next step in thickness is the 1/2 OSB sheathing covered with tietac (don't know if we can use brand names) with 2x4 stud wall insulated with pink fiberglass and poly vapour barrier. this sits on a foam gasket atop the 3' block 3) next step in is the bare concrete block (inside and outside) To proceed there is the suggestion to 1) affix 1.5 xps to the old cottage siding 2) bump out with strapping and xps 1.5 to match the above xps 3) install enough xps depth on hte 3 foot block wall the match the above in depth and then strap over that assembly to affix siding. Interior 1) 2.5 inches of eps on the 3 foot block wall with carried up onto the top of the block wall creating a countinuous "shelf. Cover with drywall or pine boards. 2)remove the vapour barrier on the 2x4 wall and add rockwool or fiberglass or other insulation without vapor barrier-no foam 3) add bats to old cottage 2x4 walls from inside add 1' of reflective stryrofoam. 4) sprayfoam attic space to close off air leaks with 1-2 inches 5) instal baffles on the rafters to keep 2" minumum air space to roof and contain the blown in cellulose insulation. 6) add 3" of foam over existing shed roof and reroof... Although he said it may make more sense to remove the old siding and re-sheath and foam since there would only be the one plane. Or move to Florida in the winters and leave it as is strapped and sided with no insulation! You have no idea what thankfulness I have for you folk taking your valuable time to help a struggling person to learn and to make a difference not just for me but for others as well.

Line breaks and paragraph breaks make it easier to read/follow. A lot of formatting with some web browsers get ignored or don't display correctly on this site, but both Chrome & Firefox work-mostly. (I'm using Firefox on this machine.)

By "depth" I'm assuming you're talking vertical depth, the layers of your house cake(?)

To affirm what your saying, the three levels are:

1> The top 8' is the original cottage with the wood siding (or do you really mean sheathing?), uninsulated

Q: Is it plywood or plank sheathing or something else on the exterior?

2> Below that is a half-inch OSB sheathed 2x4 fiberglass insulated pony wall covered with tietac (I don't know what that i- I'm assuming a housewrap) with interior poly sheeting, all resting on foam sill gasket on top of the CMU wall.

3> At the bottom is an uninsulated un-clad CMU wall.

It that the picture? (couldn't access the photobucket pics today for some reason.)

Then the suggestions...

> 1) affix 1.5 xps to the old cottage siding

I assume you mean "sheathing", but 1.5 XPS derated to it's warranteed R6.75 isn't sufficient for dew point control at the sheating on a 2x4 wall in zone 6 if the studs are insulated. At 1.5" polyisocyanurate would be enough. At 2" EPS would be enough.

>2) bump out with strapping and xps 1.5 to match the above xps

Assuming you mean to say that the pony wall's sheathing doesn't extend as far to the exterior as the sheathing on the original cottage above. How much is that step out? If the total foam depth on the 2x4 fiberglass insulated pony wall would be 2" or more, it would have sufficient exterior R for dew point control using any foam.

>3) install enough xps depth on hte 3 foot block wall the match the above in depth and then strap over that assembly to affix siding.

Sounds good so far, but use unfaced EPS rather than XPS, to promote outward drying of the CMU, since the foam sill gasket isn't really an adequate capillary break.

>Interior 1) 2.5 inches of eps on the 3 foot block wall with carried up onto the top of the block wall creating a countinuous "shelf. Cover with drywall or pine boards

If pine boards it needs to be at least 3/4" thick over the foam board to meet most fire codes. Where the framed wall-foam transitions to the CMU wall foam it needs Z-flashing (Anywhere the sheathing type changes that's the case.) The Z-flashing can be done with the same 6" EPDM flashing tape commonly used for windows, or it can be sheet metal bent on a brake, but the EPDM is far less thermally conductive, and thus a better choice.

>2)remove the vapour barrier on the 2x4 wall and add rockwool or fiberglass or other insulation without vapor barrier-no foam

That works if there is at least R7.5 of exterior foam if insulated with fiberglass, or at least R8 if rock wool or high-density fiberglass.)

>3) add bats to old cottage 2x4 walls from inside add 1' of reflective stryrofoam.

Skip the styrofoam if there is less than R7.5 on the exterior, and DEFINITELY skip the foil facer. (BTW: Styrofoam is the trademark of Dow referring to it's XPS products, but I think you really mean EPS here.) Adding an additional R4 to the interior would require bumping the exterior side to R11+ for dew point control. The foil facer is a true vapor barrier at less than 0.1 perm, 1.5" of XPS is less than 1 perm, which meets the NBC definition of vapor barrier. The combination of 1.5" XPS on the exterior and a foil facer on the interior creates a moisture trap. A safer stackup with comparable performance is to use 1" thick 1.5" wide strips of polyiso attached to the framing and fill the 4.5" of depth with a compressed rock wool batt designed for 2x6 framing. The compressed batt would perform at about R20, and would need R11.25 on the exterior using IRC prescriptives, but with 2-mil nylon (Certainteed MemBrain) on the interior under the wallboard, detailed as an air barrier it would be relatively safe. With only 1" edge strips it's still pretty easy to long-screw or long-nail the wallboard in place.

Before adding the batts, air seal the framing to the sheathing inside of each stud bay with polyurethane caulk.

> 4) sprayfoam attic space to close off air leaks with 1-2 inches

That's not the cheapest way to seal off the ceiling plane, but it's effective.

>5) instal baffles on the rafters to keep 2" minumum air space to roof and contain the blown in cellulose insulation.

The IRC calls out a minimum of only 1". It's fine from a moisture control point of view to go larger, but it knocks R3-R4 off the insulation that you can get out over the top plates of the walls, undercutting the overall performance a bit.

>6) add 3" of foam over existing shed roof and reroof

In climate zone 6 at least half the total R needs to be on the exterior to have dew point control at the roof decking. So if the shed roof has 2x4 rafters that you can fill with cellulose or batts you'll be fine with 3" of polyiso, a bit marginal but probably still OK if it's EPS or XPS. If it's 2x6 rafters it's not enough.



>Or move to Florida in the winters and leave it as is strapped and sided with no insulation!

That works, depending on what part of Florida. Between sea level rise and hurricane storm surges things are getting a bit hairy, even in some inland locations.

Line breaks and paragraph breaks make it easier to read/follow.

A-Thanks for the tips!

By "depth" I'm assuming you're talking vertical depth, the layers of your house cake(?)

A-Maybe plane would be a better word for me to have used but yes "layers"

To affirm what your saying, the three levels are:

A- 1> The top 8' is the original cottage with the wood siding on top of thin plywood and uninsulated



A -2> Below that is a half-inch OSB sheathed 2x4 fiberglass insulated pony wall covered w housewrap) with interior poly sheeting, on 2x4 wall part only all resting on foam sill gasket on top of the CMU wall.

A- 3> At the bottom is an uninsulated un-clad CMU wall. ...

A- Yes It that the picture? with slight changes

Then the suggestions...

> 1) affix 1.5 xps to the old cottage siding

A- no siding over thin plywood.......I assume you mean "sheathing", but 1.5 XPS derated to it's warranteed R6.75 isn't sufficient for dew point control at the sheating on a 2x4 wall in zone 6 if the studs are insulated. At 1.5" polyisocyanurate would be enough. At 2" EPS would be enough.

>2) bump out with strapping and xps 1.5 to match the above xps
A -OK

Assuming you mean to say that the pony wall's sheathing doesn't extend as far to the exterior as the sheathing on the original cottage above. How much is that step out?
A- each step out (transidion) is about 3/4"

Sounds good so far, but use unfaced EPS rather than XPS, to promote outward drying of the CMU, since the foam sill gasket isn't really an adequate capillary break.


If pine boards it needs to be at least 3/4" thick over the foam board to meet most fire codes. Where the framed wall-foam transitions to the CMU wall foam it needs Z-flashing (Anywhere the sheathing type changes that's the case.) The Z-flashing can be done with the same 6" EPDM flashing tape commonly used for windows, or it can be sheet metal bent on a brake, but the EPDM is far less thermally conductive, and thus a better choice.

>2)remove the vapour barrier on the 2x4 wall and add rockwool or fiberglass or other insulation without vapor barrier-no foam

That works if there is at least R7.5 of exterior foam if insulated with fiberglass, or at least R8 if rock wool or high-density fiberglass.)


Skip the styrofoam if there is less than R7.5 on the exterior, and DEFINITELY skip the foil facer.
A-OK



A safer stackup with comparable performance is to use 1" thick 1.5" wide strips of polyiso attached to the framing and fill the 4.5" of depth with a compressed rock wool batt designed for 2x6 framing.
A: Excellent idea

The compressed batt would perform at about R20, and would need R11.25 on the exterior using IRC prescriptives, but with 2-mil nylon (Certainteed MemBrain) on the interior under the wallboard, detailed as an air barrier it would be relatively safe.
A: Ok that avoids the moisture trap, right?

With only 1" edge strips it's still pretty easy to long-screw or long-nail the wallboard in place.

Before adding the batts, air seal the framing to the sheathing inside of each stud bay with polyurethane caulk.
A- Right

> 4) sprayfoam attic space to close off air leaks with 1-2 inches

A: That's not the cheapest way to seal off the ceiling plane, but it's effective. Suggestions??

>5) instal baffles on the rafters to keep 2" minumum air space to roof and contain the blown in cellulose insulation.

The IRC calls out a minimum of only 1". It's fine from a moisture control point of view to go larger, but it knocks R3-R4 off the insulation that you can get out over the top plates of the walls, undercutting the overall performance a bit.
A: Got it.

>6) add 3" of foam over existing shed roof and reroof

In climate zone 6 at least half the total R needs to be on the exterior to have dew point control at the roof decking. So if the shed roof has 2x4 rafters that you can fill with cellulose or batts you'll be fine with 3" of polyiso, a bit marginal but probably still OK if it's EPS or XPS. If it's 2x6 rafters it's not enough.

A: ok batts and poly iso--no venting requited (the shed roof is not open to the rafter space)?

A: could I hire you to give the builder a list to follow?
Thanks again

What a ride! New builder has torn rotator cuff-needs surgery. Plan as he sees it: 1) 1.5 inches of EPS tacked to existing sheathing and down into ground 2ft to insulate the slab edge- all taped 2) Attach 1x4 furring to original framing (2' on center) and to the CMU 3) Hang siding 4) remove shingles and add 3 or 4 inches of polyiso on shed addition only (which is not vented) new roof sheathing and then new shingles 5) add poly film to ceiling on top floor caulked and sealed. Install pine ceiling t@G 6) Continuous vented soffit and fascia on old cottage section 3 vents on roof. 7) baffles in rafter bays and blow in cellulose 18" 8) Caulk any cracks in slab with self leveling polyurethane caulk and install 7/16 eps with reflective barrier on both sides and cover with OSB. 9) 2" EPS on interior of 3 ft knee wall with no vapor barrier covered with 3/4" pine t@G 10) 2 x 4 knee stud wall add 1.5" strips to make 2x6 depth and use fiberglass bats without vapour barrier 11) doors with be raised 1.5 inches. Have we got a way forward here that makes sense in climate 6?

There needs to be Z-flashing on the foam where it transitions from sheathed wood construction to the foundation, directing moisture coming down the sheathing to the exterior. (This is not just best-practices- it's in the NBC, not that I can easily point you to the chapter & verse.) That flashing can be EPDM flashing tape when it's foam that thin, and EPDM is orders of magnitude less thermally conductive than any metal flashing.

Poly sheeting on the interior side of an unvented roof is a moisture trap, and a code violation. Using poly sheeting as the primary air barrier under t & g ceiling is almost guaranteed to fail. Half-inch gypsum is a much more robust air barrier.

If the R-value of the exterior foam exceeds the R-value of the cavity insulation in the shed roof it's fairly moisture safe with just gypsum board painted with standard latex primer, but "vapor barrier latex" primer would be OK too.

There needs to be an interior side air barrier behind the t & g on the kneewall too. EPS doesn't cut it as an air barrier- not even close. Putting the 2" EPS on the exterior side of the kneewall is adequate for dew point control at the foam/fiber boundary in zone 6, but again, half-inch gypsum pained with latex primer is the better choice behind the t & g.

Many thanks to all that have made sound and wise suggestions. We press on with the build slowly but surely.

One last questions: we have 1.5" xps on the exterior extending 2' into the ground and then another 1.5" of xps on the edge of the slab for a total of 3 Inches

Considering insulating above the slab as under the slab is not, nor is it on ploy but is on 6" of clear coarse gravel, and considering the main floor will be kitchen /living/dining open concept 780Sq ft and the source of heat a propane fireplace and considering the 3" of xps on the slab edge what would be an appropriate floor assembly-height is a bit of an issue.I Differnet for tile vs luxury vinyl vs laminate....