Back in the fall, I had 4 inches of spray foam insulation put in the floor and around the holding tanks. Now, it’s time to do the shell. Because of the room available in the walls, we will get between 1.5 and 2 inches of foam giving an R value of between 9 and 12, while the floor is R24.
Tape up anything you don’t want the spray foam on. It has a serious adhesive quality and if it gets on your fans or windows, it will be very time consuming to get off. In the case of the vista view windows, I taped them with duct tape and we will spray foam right over them and dig them back out later – this is the only way to ensure good coverage along the frames and between the aluminum channels.
Below are a few photos of the actual spray foam process. The foam is very hard and adds a fair bit of structural integrity to the Airstream, it also secures all the electrical wires in place. Because the aluminum walls no longer bend when pressure is applied, it makes polishing the outer skin faster and easier. The foam itself is dense but extremely lightweight and solidifies almost instantly.
Be sure to have all your wires secured tightly to the walls before foaming so that none protrude when you have to shave the excess foam off – you may cut a wire in that case. Place the wires for your fixtures as close to the location that you want the lights, outlets, switches, etc. Once foamed over, they don’t move. I also wanted to have access to the bolts holding my solar panels down in the future, so I cut cardboard paper towel rolls in half and glued them to the ceiling around the bolts to prevent the spray foam from covering them.
After spray foaming you can chisel the excess away by hand, or use your polisher to do it in a fraction of the time! Take the wool polishing pad off and replace it with 80 grit hook and loop sandpaper pads and you can have the whole trailer smoothed out in half an hour.
It is very important to wear a good quality mask and eye protection. You are going to be covered in spray foam dust.
