Cutting back Insulation Spray foam

Our house is 5 years old and has spray foam, we have an oversized attic with some open space and I want to hang plywood against the wall so I can hang a dartboard on the wall. My wife and mother in law think cutting the spray foam insulation flush with the wall so that I can hang plywood against the wall will sacrifice the integrity of the insulation, I think they are inaccurate and plywood would far makeup the different for any minor amount of installation that needs cut flush to the wall. I am just looking to get some positive responses to convince them cutting the installation will be fine.
Thanks!

 

I am confused (easy to do) are you saying cut insulation back to studs? Don't know how insulation would hang out past wall

 

Pictures would help, but it would be common to spray the foam so it surrounds the studs, reducing the thermal bridging. So yes it will affect the performance of the foam insulation. But, for a limited area, and in a warm climate where condensation is not a concern, I doubt anyone could measure the difference.

An additional concern might be the exposed foam itself. Most codes require a thermal barrier covering spray foam. There are several solutions available.

Bud