The Transit has a window in the sliding door and two back door windows. I was not concerned about noise reduction so wanted the most "R" value from insulation. Only added 1/8" Rattletrap noise reduction material to the three window indents to level out the surface around the Ford installed noise reduction pads. There were several different methods used to insulate depending on the location. Wiring is not buried in the walls. Cords are routed inside and behind cabinets.
LOWER CAVITIES BELOW THE WINDOW INDENTS
There are three lower cavities. Two around the rear wheel housings and one opposite the slider door. They are about 20" high and about 4 1/2" deep. Outside the Transit there are plastic rub rails at the bottom of the body that are held in place with plastic fasteners. These fasteners leak water into the interior. So first these were sealed with Locktite PL-S40 polyurethane "window & siding" sealant. Covered each fastener. Then two coats of "insulating" paint were applied to the inside of the van walls. The latex paint has small hollow ceramic balls mixed into the paint. The ceramic balls were supplied by www.hytechsales.com. Some suggest that the insulated paint is useless. Did do a test on the Transit forehead above the windshield. Painted one side and could feel a difference in the steel temperature between the painted and unpainted sides. So it does some good and is easy to apply and should supply some additional rust prevention.
Installed 1/4-20NC prebulbed .020-.280 grip range inserts into existing wall holes. Bought inserts from Jay-Cee sales part # RN252028PNB. Then two layers of 1" thick Aerocel closed cell foam sheet insulation was glued to the wall steel with Aeroseal contact adhesive. Both supplied by www.aeroflexusa.com. The foam insulation is flexible so it can be folded to get it through openings. The second layer was used to cover any joints between foam pieces on the first layer. Next a layer of Relectix was glued on top of the foam with 3M77 spray glue. Reflectix is worthless for insulation value if an air gap is not provided. In these cavities there is about a 2" air gap between the Reflectix and the back of the wall covering. The 1/4" plywood wall covering has a 1/8" layer of closed cell foam glued to the back with 3M77 spray glue. The purpose of the 1/8" layer of closed cell foam is to prevent squeaking. The panel is held in place with 1/4-20NC x 1" PVC plastic bolts.
The 1/4" plywood wall panel dimensions were obtained by making a cardboard pattern. Measured for the panel and cut the cardboard. Next the cardboard was taped in place with duct tape. A wood block and a hammer were used to tap each prebulbed insert location to create an indent in the cardboard. Removed the cardboard and drilled the bolt holes. Bolted the cardboard in place. Marked the exact centerlines of each bolt and made notes on the cardboard perimeter of where I needed to add or remove cardboard. Used cardboard pattern to make the plywood wall cover. Fit the plywood and then removed it to be painted. Had paint mixed to match the van steel color.
UPPER CAVITIES ABOVE THE WINDOW INDENTS
There are four upper cavities. Used same insulation procedure for the four cavities that was used on the lower cavities. Since there aren't any trim fasteners in the upper cavities sealing fasteners was not required.
TWO REAR WINDOW INDENTS
These indents can not be completely filled with insulation. Needed to limit the insulation thickness so I could obtain a cross van bed length of 73 1/2". First two coats of the insulating paint were applied to the interior of the van steel walls. Ford put two noise reduction tiles on the van steel walls. In order to obtain a flat wall surface for the insulation, Rattletrap noise reduction material was applied around the Ford tiles. Next blocks of 1 1/2" thick rigid polyisocyanurate were glued in place with 3M90 spray adhesive. Blocks held in place until glue cured with wood sticks between opposite wall and the insulation. Left about a 1/2" gap between the insulation and the steel stiffeners at the top and bottom. The wall rigid insulation was made in two pieces with a 1" wide horizontal seam so insulation would fit tight against the curved steel walls. The corners of the insulation were cut off so later Great Stuff "gaps & cracks" spray foam could be used to bind all the pieces together. Used the spray foam around the perimeter and in the gaps to lock the insulation in place. Trimmed all the excess spray foam with a loose hack saw blade to get a flat surface. Next 1" rigid insulation was glued on top of the steel stiffeners to obtain a flat surface. The gaps were filled with Great Stuff and the excess was trimmed with the hack saw blade. The insulation was covered with indoor/outdoor carpet glued on with 3M90 adhesive. When using the Great Stuff spray foam it is important to warm the can and shake it before use. Foams much better when warm.
ONE WINDOW INDENT BEHIND THE DRIVER SEAT
Same procedure was used on this indent except indoor/outdoor carpet was not used. In place of the carpet an additional layer of 1 1/2" rigid insulation was glued on top of the 1" and 1 1/2" rigid insulation. Next Reflectix was glued on top of the rigid insulation. This wall is behind the refrigerator and shower so Reflextix could be exposed. There is an air gap. No wall paneling required. There is a 1 1/2" gap between the insulation and the back wall of the shower. Did need to run some cords between the insulation and the back shower wall. At the bottom of the window indent a 1" closed cell foam pad was glued in place. The cords sit on the foam behind the shower wall.