Is the wall totally below grade? Depending on where you are located, it may be geothermally correct all year round. If insulation is needed, I would recommend 2" XPS attached to the cmu with PL Foam adhesive and seal all the joints with Tyvek tape. You have CBU down now, so what are the future plans for the floor?

 

With a new home, the outside of the foundation wall should be constructed with either a liquid or plastic membrane to prevent water intrusion through the block and with a foundation drain to carry away any water. You shouldn't need to do any treatment to the inside before applying the insulation.

 

Ditto on the above suggestions especially thicker foam board.
Where are you ?
Bud

 

The wall is about 75% below grade. I have a piece of 1/2 double faced foil insulation on my concrete floor with durlock cement board on top, this is where the furnace will be laying horizontally on 8 inch blocks with rubber vibration pads under each corner. I wanted the insulation down to keep any moisture or cold if it does comes up from the concrete floor away from the bottom of the furnace to help keep my wires and bottom of the cabinet from any rust or corrosion. The outside wall just had tar roller on it, no plastic membrane. There's no foundation drain on the outside wall, just a corrugated pipe around the inside wall that goes to the sump pump. The outside soil grade runs about a 22 degree pitch up the wall for water runoff to help keep it away from the wall. Your recommendation would be "not to" put foil faced insulation on the wall, is non foiled better?

 

I live in a rural area outside Buffalo NY, we do get our share of snow at times. Most of the winters I do have snow above the block walls which helps as an insulation but the inside walls do get a little cold.

 

Guess I'll have to find another way to insulate, I've been finding out that foam board (by code) shouldn't be use in any unoccupied spaces such as a crawl space because it's a fire hazard. I could use it but it can't be left exposed, the blocks would need a vapor barrier to prevent mold or mildew and has to be covered with a 15 minute fire rated drywall. I'll just have to leave my duct register open 1/2 way to help keep the crawl space warmer and use a dehumidifier to remove any moisture. By the time I buy a vapor barrier product, form board, furring strips, and drywall, it's a bigger cost than I expected.

 

Making notes here while I review your thread.
Thermax: A little history. Thermax has a foil face that has been tested and approved for most applications to be installed without the added thermal barrier. But it isn’t the only foil faced rigid foam. I selected 1” Dow Tuff-R. Most of my basement is below grade and the soil provides extra insulation value. How much protection Tuff-R provides is unknown because Dow elected to not test it, they already had one product. If you choose Thermax you should still get your local authority to approve it.

Did they install a vb under that crawl slab ?
Heat loss and related cost in an uninsulated crawl is significant. Related energy savings over time will offset much of the insulation costs.
Best with more than 1/2” insulation. 2” as suggested.
Looking at 17 sheets of 4x8 foam board for a 1,200 sq ft crawl.
Has your sump pump been active ?
Creating a conditioned crawl space will give you warm floors above.
Note, in addition to insulating the walls you should air seal and insulate the rim joist cavities.
Bud

 

I misunderstood your plan. I thought you were "finishing" the crawl, thus the reference to XPS. You are correct in that it must be covered. What Bud suggests with Thermax is a good starting point.

 

Thanks guys, I'm going to look into that Thermax and Tuff-R, I'll have to find someone in my area that carries it. A plastic vapor barrier was put down before the slab was poured, floor is always nice and dry all year round.
My sump pump is only active if we get a lot of rain in the fall, or when we have a winter thaw in the spring.
I already spay foamed any cracks in my joist cavities and they're insulated, also plan on insulating between my floor joist too.
The block that is above grade will sometimes get wet in a hard blowing rain and leave a few damp spots inside the crawl space, if I just glue on the foam board is there a possibility of getting mold or mildew build up between the block wall and the foam board?

 

If you create a sealed crawlspace with walls insulated equal to your local requirement for basement walls you won't need to insulate between the joists. You can skip the insulation between the joists and use what you save to beef up the r-value of the wall insulation.

Creating a sealed crawlspace

 

Thanks for the info, seems a sealed crawlspace is the best way to go. I couldn't find one supplier in my area that carried Thermax or Tuff-R, did find John Manville fire rated foam board at Lowe's, and they carry 2" also. Thanks again for all the help, I really appreciate it..

 

Come back and share your progress.

 

I will, thanks. Happy Holiday's!