Spray foam vs sheets

java

Expedition Leader
Thinking about insulation.

Who has used spray foam and who has used sheet foam? I like that spray foam will not leave any gaps for condensation, but its it really worth the extra price?

It will be going over an aluminum outer skin.

:beer:
 

pappawheely

Autonomous4X4
Subscribed. I like the spray foam for the same reasons but can't seem to find anything that is cost effective.
 

Coachgeo

Explorer
Did some reading on these bulk spray foams like that in previous post. Not the can stuff. R factor is higher than can stuff. BUTT Think there is a fire retardancy issue. If recall right to meet reasonable fire safety they must have an air space before interior wall AND be covered with and at least 1/2 drywall or similar fire retardant panels. Don't quote me though...... read all the info closely.
 

java

Expedition Leader
Did some reading on these bulk spray foams like that in previous post. Not the can stuff. R factor is higher than can stuff. BUTT Think there is a fire retardancy issue. If recall right to meet reasonable fire safety they must have an air space before interior wall AND be covered with and at least 1/2 drywall or similar fire retardant panels. Don't quote me though...... read all the info closely.

Ever the possibility, but sheets will have the same issue, foam is inherently flammable.

Spray if you can do it.
Spray effectively glues together anything it touches, will add greatly to strength. You can get by with less framing members.
Seals & secures wiring and such too.

I used sheetfoam in a lowbudget camper fixup, Its ok for what it is. Its handy I can unscrew a wallpanel to fiddle around with wiring & stuff. But that camper was never going to be "finished" anyway. I planned it an ongoing job of tinkering & modification.

Thats true, I didn't think much of the additional rigidity. I will likely use conduit or surface mount the electrical, just for ease of repair.
 

rruff

Explorer
Who has used spray foam and who has used sheet foam? I like that spray foam will not leave any gaps for condensation, but its it really worth the extra price?
It will be going over an aluminum outer skin.

Spray foam is best if you need to go around pipes and wires and things. On the exterior skin I see no advantage to it. You don't need to leave gaps with sheet, and if there are, get some rattle can foam and spray the cracks.

After you apply foam you need another skin. What will that be? Also the foam won't be structural, so how will you structurally attach the outer skin? Seems like you'd want the aluminum on the outside. Or am I misunderstanding you, and the foam will be on the inside?
 

Joe917

Explorer
Spray foam will be far superior to using sheets. Almost as good as building with composite panels. You could try a commercial spray foam insulation company and arrange to bring the truck to a location they are working at to get a better price.
 

tommyt

New member
I have done extensive reading on spray foam vs foam board or other insulation. As others have said, spray foam is far superior to other insulation. The only drawback if you either DIY or have someone professionally do it, is it needs to be done in thin 1/2" (expanded) coats to prevent distortion of the body panels. Pillars and less accessible areas can be filled with the can foam...
 

Betarocker

Adventurer
Instead of having the sprayfoamer come to you, go to him. Find out where they are doing a house and drive over and get him to do the application. Tape off everything you want to protect.
 

Coachgeo

Explorer
Instead of having the sprayfoamer come to you, go to him. Find out where they are doing a house and drive over and get him to do the application. Tape off everything you want to protect.
Was thinking the same myself cept was actually thinking the cab since I want to use the behind the seat area for a bunk ... that and the AC system won't have to be as big either. Won't be the first time someone has driven somewhere with a milk crate for a seat. Just don't know what to use as a cover over the foam that has some fire retardency yet can mold around the curves of the body where needed. (FMTV/LMTV)
 

tommyt

New member
Far superior in what sense?

I know this was not addressed to me but since I feel the same way, I'll mention a few.

It will add strength to the body panels and further reduce noise.

Spray foam will cover and seal all corners. voids and cracks.

It adheres directly to the body panels and pillars and can be sprayed to the depth of the pillars whether that's one inch thick or 4" and once dry, excess that expanded beyond can be cut off. This will give you maximum R value and practically eliminate condensation.

Sheet foam is flat and fairly rigid. Body panels are usually slightly curved and have additional cross bracing and other aesthetic bends. There no doubt will be an air gap between the body panel/skin and the foam sheet. Unless a sheet is perfectly sealed by can foam on all sides, the air in that gap (between foam and skin) will either heat up and rise and be replaced by cooler air at floor level or cool off and sink being replaced by warmer air from the ceiling area. This is called convection and can be a awesome principle to passively heat a home...
 

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