I am planning on using spray foam to insulate my basement. I was speaking with a cousin who is in the remodeling business over the weekend and he suggested I use "L" brackets on the studs to keep the walls from bowing. He said he has done several basements where he used spray foam and had a few problems where the foam caused the walls to bow when the foam expanded between the studs and the concrete. He said he attaches an "L" bracket to the concrete and then screws it to the stud. Has anyone ever had the problem with studs bowing. I know the certain types of spray foam expand more than others and if the correct type is not used on windows and doors can cause the frames to bow in making it almost impossible to close.