The access door built into the floor between the bed and wardrobe closet went down last week. What holds that door up is a series of 1 1/4" wood screws spaced around the access hole holding up a ledge which the door simply sits upon. The ledge is flat aluminum plate, 3/16" thick by about 2 1/2" wide. Of the 2 1/2" width, about 1 1/2" is attached under the plywood floor. The other 1" or so of the aluminum plate creates a ledge around the perimeter of the square-ish hole in the floor and supports the access door. The floor and access door generally appear to be two thicknesses of 3/4" plywood laminated to form a nice, substantial 1 1/2" thick floor.
The problem was the cheap wood screws which were installed to hold the flat aluminum piece up to the bottom of the stationary plywood floor. The screws are about 1 1/4" long and with all the vibration, moisture and dirt rising up from wet roads, and walking on by we folks in the bedroom, they just worked loose and many had fallen out. Finally, the access door gave way on two of the four sides and "caved" in about 1/2".
My fix was to purchase a right-angle adaptor for my cordless drill and to drill 5/16" holes up through the aluminum plate and laminated floor. Then I placed 1/4" carriage bolts down through the floor and through the plate where I put a flat washer, a lock washer and a nut. The carpet was lifted from the floor just far enough back so that I could get the carriage bolts into the holes without putting holes in the carpet. Thus, the carriage bolt heads are concealed under the carpet and cannot be seen or felt underfoot.
After the bolts were all in, the access door replaced and I was satisfied with the results, I then placed adhesive under the carpet I lifted, let it dry for 24 hours, and cleaned the whole bedroom carpet with the shampooer I use in my house and rentals. The access door is now SUBSTANTALLY better supported and should last for the life of the coach.