My Dad's motorhome had delam below the window at the dinette. We pulled the window, wedged open the area and pored epoxy down the wall. We had it parked next to a building. After filling with epoxy, we used a sheet of plywood next to MH and wedged 2x4's between building and MH to hold side in until epoxy set up. Put window back in and he had no more problems with it.
CAUTION!!!! Use epoxy that will not eat up the foam. Some epoxy will melt the foam and cause you more problems.
Test small amount of epoxy on your foam, before you do the job.
Ron & Ellen Norton
2016 Grand Design Reflection pulled by 2012 Ram 3500 4x4 6.7 Cummins