You mentioned $300 and a saturday for your square footage, are you looking at EPS(white beadboard) from Menards or something like that? If so, the cheap EPS they sell makes a huge mess cutting and breaks really easily, foam board from a fabricator will be a higher quality and not much more if you can find it and easier to work with, any EPS isnt going to meet fire barrier, nor is foil faced polyiso or pink/blue board.

Bigger problem you'll have is when you go to sell and a home inspector tells the prospective buyer there is no fire barrier over the foam. You could stud out a wall in front of the foam board and fill with fiberglass batt, cover the foam with drywall or use Thermax foamboard to have a legal fire barrier. All expensive options, that is why you see lots of new houses with basements studded out at 24" on center filled with batts with mesh over the whole deal with no foam board behind from the get go, that is the cheapest way to meet code in WI rather than deal with the transition of exterior foam board that sticks past the face of the siding plus the foam board cover. My preference when I build is foamboard with fiberglass filled stud wall in front of it, Thermax is over $30 for 1" sheet.

Bottom line is look at Dana1's initial scratch for BTU reduction, it is significant. You will get your money back, how fast you get your money back is the hard to answer question but you will certainly be adding value to the house if its studded out, less so if you just have foamboard because it wont be ready to finish to the buyer.

If you follow others advice to batt your floor, wrap ducts, even seal your ducts your basement temp is going to drop probably to an uncomfortable level, you are hanging out down there so I wouldnt do those things.

Removing the wood beam and installing steel, while doable would be REALLY expensive, if you are worried about foam board not penciling out I cant see how you would shell out to change the beams out. A house moving company would be the ones with the jacks and cribbing to do that.

And take care of the fireplace cantilever if you havent, those things are usually built really stupid, and leak like crazy. Not just in the basement but the wall cavity is usually connected to the outdoors as well. Ive peeked into quite a few in the basement where Ive removed batts and can see outside, or even better when you take the batt out and the only thing seperating outside is a piece of vented soffit.

From an energy use point of view there's nothing much to be gained by insulating the joist bays, once the walls are insulated. If there are ducts & air handlers, or a boiler & heat distribution plumbing in the basement it isolates the distribution & standby losses to the basement, where that "lost" heat can't accrue to offsetting the heat load of the upper floor, only to the basement.

The fact that they are I-joist even makes insulating them with batts complicated, and nearly impossible to do well, though putting up a ceiling and using blown insulation would work. But there is no "payback" in insulating the joist bays any more than there is payback in insulating partition walls between rooms on the first floor. It helps with isolating the heating zones, but has essentially zero effect on the total energy use.

Perhaps someone can explain the meaning of section 4.2.2 here or some of the stuff here. "...most grades of STYROFOAM XPS insulation can be used exposed to the interior of the building in most circumstances...

Interesting, the version before the one you posted only mentioned attics and crawlspaces allowable without thermal barrier which is allowable in WI.

Last discussion I had with a code official maybe a year ago was our 250 F requirement which Thermax meets and the other foams do not. I just looked up Styrofoam and found it listed to 165 F but I didnt check the date to see if its been bumped up.

The language at the bottom of the document of course says local regs take precedence but worth a look, savings on 2" would be almost $1000 on a typical house.

Complete finish is the ultimate goal, I have 105% equity in the house itself just challenging to find reputable contractors to do that. At this point I'd do the messy foam board and hopefully soon find someone to frame it and complete the finish but I live here with just my gf so we aren't pressed for space either so it sits (been here 1.5yr now), I'd like to see 10% btu reduction in just the verticals, gas company just emailed me and said I use 4% more fuel than "average" for my home type not sure how accurate that is.

Posted By ls3c6 on 23 Dec 2017 02:57 AM
Complete finish is the ultimate goal, I have 105% equity in the house itself just challenging to find reputable contractors to do that. At this point I'd do the messy foam board and hopefully soon find someone to frame it and complete the finish but I live here with just my gf so we aren't pressed for space either so it sits (been here 1.5yr now), I'd like to see 10% btu reduction in just the verticals, gas company just emailed me and said I use 4% more fuel than "average" for my home type not sure how accurate that is.

I hate those "You use 10 gajillion percent more than..." mailings.
I currently use 150% more than my neighbors do.

DUH.

I work from home and have multiple electronic devices (and BEEFY computers) running more or less constantly.
Also, during the summer, I have the AC on so I don't cook (I'm one of those people who think that 68 degrees is nice, if I can sit, naked, on an ice block in front of a fan).

My neighbors leave for work in the morning and don't return until the early evening.  So everything but the appliances are turned off.

Do the math.

at this stage it's unlikely i'll do anything else than foam board the verticals, can I expect much from that? I'd like to find a contractor to complete the finish but for some reason finding reliable and knowledgeable guys is near impossible for me.

I was going to leave the joist pockets empty I thought that was a no no to insulate due to humidity etc? I would also like to remove that entire beam and replace with metal but again, finding contractors is near impossible for me, I was going to leave the floor as is since it's at least 62f

Yeah if you know of anyone let me know, I've had enough oil leaking Silverados and ppl talking out their butt over here

Well I bought 2" xps and did the foundation walls, taped seams and spray foam top and bottom... What an improvement now the basement is .5f colder than main level with just 2 4x10 supplies and no returns. I'm working with a builder to come in and finish the space I think this will be nice when done! Curious to see if heat load drops dramatically.

Nice!

Glad it worked out for you.