Help! I am trying to convert an old bomb shelter that at one time opened to the outside. After many remodels it is now under a bedroom. After locating the stairwell we now need a way to create or purchase a door in the raised wood floor. I think a "lift assist" door may be a good solution as the opening needs to be rather large to accomodate headroom in the stairwell. Any advise? May general contractor is stumped.