Foam board frost barrier

[Reit38]

So 90% of my concretehas already been poured in my shop. I ha e a small section left ahere I plan on putting a small bathroom. I didn't have time to run water and drain lines last year before winter.

My question is, none of my concrete has foam board going vertical down past the frost line. Would I gain much by ha it on the 2 sides of my bathroom floor?
The bathroom is going to be in the corner of the building approximately a 5x10 room.

was thinking of doing like (b) from the photo
https://images.app.goo.gl/KtVZF5jmSS2Rf6vR9

 

[WisJim]

If you plan on heating any part of the building, you should install the 2" foam board around the perimeter. It is usually installed after the concrete is done. Personally, I would do the entire building perimeter. It only took a few hours to do my 24x40 building, with a couple of people using shovels. It got covered with aluminum flashing material that matches the color of the steel siding on my shop.