Question about insulating a floor over a crawl space

[Citation]

I know this isn't a garage question but this place has the knowledge. My house has a side room, about 10x16, that was added on by a previous owner well after the original house was built. While the old house is built over a basement, that room is built over a crawl space that is accessible via the basement. The exterior walls of that crawl space are insulated with spray foam. The bottom of the crawl space appears to be sheeting over pea gravel. The floor is uninsulated.

Today I noted that the floor temperature in that carpeted room was 56F. That certainly makes the room feel colder in the winter. Is there any reason why I shouldn't insulate the underside of that floor? Given the spray foam, I'm assuming the original builder had some plan for insulation and perhaps wanted to make sure that area never froze? The only services that run under the room are electrical, a radon pipe and two flex ducts that service the room.

My plan was to put some fiberglass insulation between the joists with the vapor barrier towards the floor. Any issues with that plan?

Thanks!

 

[Kaizen]

Google this and you will see there are a ton of opinions. Even saw some say not to spray foam foundation. All about moisture and mold. I’d do it and monitor the humidity levels. Theoretically the plastic is keeping moisture from coming up but there usually is a way. Right now any goes to rest of basement or to house. Adding insulation will reduce that ability. Meaning it will stay in insulation. Good place for sprayfoam if you can afford it. Otherwise do ruxul or something as I think it doesn’t hold moisture??remember there is something like that


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[66Caprice]

I spray foamed the underside of my floor. Best thing made a huge difference in the temp of floor.