Canuckowner, sorry I didn't take any pictures but I wish I would have. I was quite proud of the way it looked. A local used material seller had several hundred sheets taken from a building that was taken down. The sheets were made by Dow and were 2 feet by 4 feet. I bought 20 of them for 7 bucks a pop. Same material that's sandwiched between the luan already in the trailer. It took me the better part of a week. Lots of work. The underside is divided by C channel about 30 inches apart.
In some cases more , some less. One section was over 48 inches which I installed another frame member because I was afraid of a sag down the road. I installed the foam in two foot sections. The sides were all t and g so they locked together.
I used a normal hand saw to cut the material. Very little give in the material so I would cut just on the far side of the line I drew. The ends were trimmed to fit the C channel and installed first. Then wedged into the opposing side. A very wide chissel helped. I used Gorilla tape to cover the seams. In some cases it took several tries to get the right size. It goes faster as you get more used to it. There was 5 and a half inches between the bottom of the floor and where the bottom attaches. The foam was 3 inches thick and added R 15. I covered the bottom of the tanks with Reflectix as there was no room for foam. I also ran all the extra electrical lines that I wanted during this and installed a tank rinser on both tanks and wrapped all water lines with insulation. The tank rinsers were attached using washing machine aluminum braided hoses. I pulled all the heating vent hoses out and slid a 3 inch expandable aluminum vent hose down the inside and clamped it close to the furnace. What a difference this has made btw. The time and effort were well worth it. The floor is much stiffer. The frame rails were 68 inches apart. I still need to do the 14 inches on the outside of the frame rails on each side. That will go quick and I may have enough material but not sure. Hope this helps.
2011 Jay Feather Select 28U
2007 Silverado Crewcab LT 6.0L
Happily married and father of
two university students.