VanDweller Community Forums

Full Version: Spray foam insulation
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Pages: 1 2
This may have been asked before, if so I am sorry. I have a 1996 class B but so much of it is weight I do not use even though it all works, like hot water heater and furnace. I am thinking of upgrading to a much newer van and have my son and son-in-law help me do a van build. I have probably watched a hundred van build videos but my adult son has not. He says we should do spray foam or some kind of spray insulation which would better seal all air leaks, but I never see van builds going this route. Can someone tell me why spraying insulation is not a better method? Is it just expense. Thanks in advance for your time.
IMO it is the best method. the only motorhomes ever built and sold by any auto manufacturer GMC used this method and so do aircraft.

I have done it by using foam board insullation for the big sections and using spray foam around the edges of it to attach them in place but you have to use masking tape until it dries. then just spray the smaller areas.
here is a pic of a GMC under restoration

and the rear section where they did not cover at the factory that is done with foam board insulation like I mentioned


this really is the best way to insulate one. and you can also then add the reflectix chrome bubble wrap insulation over it too. many do this but Im not sure how effective that stuff is.
Spray foam is difficult to control the expansion rate. Too much foam in tight spaces will deform sheet metal. Too much foam in open spaces requires trimming the excess which is a difficult, tedious, messy job.
Polyiso, sold in 4x8 sheets, is used a lot because of it's superior r value and it's ease of installation. It's also fairly inexpensive. My Home Depot sells it for around $11 a 4x8 sheet for 1/2" thick. Most use that thickness because of the flexibility and then add another layer if they want. Then using crack filler spray foam in the tight spots. The crack filler does not expand as much and is easier to control. One of the major factors in insulating is what kind of climate(s) you will visit.
Not sure how much reading you have done here but there are many devoted to this topic. Probably more than you want.
There are two types of spray foam, open cell and closed cell. You do not want open cell as it holds moisture and leads to mold. The type in a can at the home improvement stores is usually open cell. Closed cell is usually a pro job. There are kits that are closed cell. And has been stated, controlling the expansion is the hard part.
^ what Brain said. highdesertranger
^^^I like that; "Brain". Wish I still had a good functioning one:-)
oops, sorry. highdesertranger
Yes glue rigid board (I prefer polyiso) then use closed cell foam to fill the gaps

and if major temp differences, energy conservation is important, make sure all the metal's well covered to prevent thermal bridging and put a vapor barrier in place before sheathing.

Read up on the kit's instructions, especially ambient temps, don't go too thick per cure and always leave an escape path
I strongly considered spray foam, but wussed out because I didn't want to learn how to do it well. It takes practice. I knew I could cut polyiso and do a very good job. Polyiso was less expensive, too, so I cheaped out compared to spray foam. My trailer with polyiso turned out superbly in regards to insulation, but the trailer inherently didn't have a bunch of air leakage. My trailer was also square unlike all the bends, nooks, and ribs of a van.

Polyiso is a high performer and would still give you first rate results if you decided to go that route.
Pages: 1 2