1905 frame house with L&P walls.  Exterior shake has been covered with asbestos(?) shingles. 

Lots of air infiltration, particularly on the end of house where a porch was enclosed.   Some walls are uninsulated and some probably have fiberglass batts in poorly sealed stud bays.

 As we are contemplating a bathroom remodel we’d like to address the air infiltration.  While one wall of the bathroom needs demolition I would like to leave the other walls intact and inject foam in the stud bays.  One portion of the wall is in a complex storage system that is over a stairway.  Tearing open the walls to spray-in insulation would be complex.  It would be a challenging space to work in.  I think it would be difficult to remove the asbestos shingles on the exterior without breaking them. Hence I think injection from the inside would be best.

Retrofoam vs Icynene?  Have seen posts about small amounts of formaldehyde with Retrofoam.  Would like to have holes be small and Retrofoam claims a series of 5/8″ holes can be used, but have not seen.

Would also appreciate insulation contractor recommendations for mid-state NJ.