Just wondering what would be the best way to insulate the floor??
Thanks
Bus,
Spray foam underneath is optimum. Considering the floor is the second biggest heat loss area you may want to do other things as well. Without foam the hot deal is to lay 2 inch sheet foam board down and then cover that with 3/8s or 1/4 tongue and groove plywood. I would go with half inch, were it me but that would be a sturdy floor were all that glued in place with 1/4 on top. That would give you roughly R30 plus whatever the two half inch thick layers of plywood yield. That would cost you 2 1/5 inches of interior height so unless you are midgets you better have a roof raise or a Prevost. I think it is a must to do either the under foam or interior sheets if you can't do both.
Then there is the carpet and pad!!!!!
HTH,
John
I went over old floor with 1 1/2 inch foam insulation, with 2X2's on 16 inch centers side to side. Covered with 1/2 inch plywood.
After seeing what other converters did, I would use 3/4 inch rigid foil faced foam with 1X2 every 2 feet. Covered with 1/2 inch ply. Looking at most buses the floor traffic is down the middle of the bus, I would run the 1X2 front to rear starting with the first piece right down the middle. Maybe even run the plywood front to rear, first sheet in the middle. Preplaning I would add 3/4 in plywood or 1x2 under critical points such as where I was mounting seats, toilet etc. On MCI's there are many air lines runing down the center of bus, under the floor, be very careful not to puncture any of them!!!!
Spray foam underneath would be great, but it is not practical on most bus's.
I welded in 3/4" x 1 1/2" rectangle steel tube over my bays making no open span on the floor more than 24" any direction. Put down three layers of 3/4" thick foil backed polystyrene insulation board (could not get 2" thick sheets). Then put 3/4" tongue & grove plywood down. Fastened with torque head deck screws every 10". Just my way.