Gabriel's Exit

We are a family of 6, with 4 adopted special needs children. We also are licensed foster parents of medically fragile infants for our county. 
Gabriel is 7,  in a wheelchair, and weighs just over 100 pounds. The only exit Gabriel can utilize independently from our home is through the garage, on the opposite side of the house from his bedroom.
We want to create an exit for him at the rear of our home. The plan is to replace the sliding door (that he can't fit through) with a French style door, then add a deck with a ramp, and a concrete walkway from the rear of our home to the front.

Every little bit will help. We truly appreciate any amount you are able to give.