Originally Posted by Monza
Ok let's hear you blow holes in the therories he states. Spray foam sounds like a good idea to me and I was considering using it. So I'd love to hear your concerns.
1. Moisture Management
Foam won't stop leaks. Aluminum skin(short of leaks) is impermeable. Very little air moves through the walls .
2. Improved Air Quality
Talks about keeping outdoor air pollutants out. Aluminum is impermeable and so little air gets through the skins it's negligible. Are you going to spray the windows, and vents closed?
3. Greater Energy Efficiency
Most heat gain for a AS is radiant. Good radiant insulation, ie Prodex, will stop that heat transfer better. Foam won't stop the conductive transfer through the ribs.
"The primary method of heat loss or gain in a vintage trailer is not conductive heat flow — it’s air leakage (convection)."
Absolutely not. Very little air moves through the aluminum shell. "Air leakage" is not convection, it's air leakage. Convection is transfer of heat through a fluid not bulk loss of the fluid itself.
4. Better Air & Water Sealing
“The real benefit of spray foam is in its air-sealing capabilities,” says Hofmann.
Very little air moves through the shell.
“Closed cell foam provides an unsurpassed water-tight barrier system that adds another layer of protection from leaks – something that every trailer’s skin battles to protect its occupants from the outdoor elements.”
Somewhat, but it can not stop leaks.
5. Noise Reduction
Here he talks about open cell but previously he talks about closed cell? Which is it?
"What is airborne noise? “Talking, stereos, gaming systems and televisions all contribute to airborne noise. By filling and sealing every crack and crevice where these sounds can travel through, spray foam insulation can reduce the transmission of airborne noise.”
How much spray foam is there going to be between the front and back of the inside of thectrailer? Zero. But this is the noise he's talking about, the radio inside, people talking inside, etc. closed cell foam is fairly rigid and will transmit sound from outside to inside. Also with the window to wall ratio you will still have more than ample sound transmitted through the windows.
"What is flanking noise? “The sounds originating from within the walls, such as plumbing runs, are considered to be flanking noise,” says Hofmann. “Spray foam can muffle these sounds by sealing the whole way around the source, creating quieter spaces uninterrupted by noises like flushing toilets or running showers.”
How much plumbing inside the walls of an AS? Just about zero.
6. Structural Component
Compared to the structure provided by the aluminum shell, this is negligible. It can also cause exterior damage to be telegraphed to the interior. Hold dents that may otherwise be able to be popped out. And make panel or segment repair or replacement very difficult.
"After many miles of bumping and bouncing down the highway, the riveted seams of Aluminum riveted trailers will loosen and become weakened. Spray foam insulation acts like a glue to bond these seams tightly"
If you think that spray foam is going to replace the strength of rivets, then another strength of materials course is on order. How about all those '50's and ' 60's trailers that have shaken themselves apart! And riveted aircraft, talk about bumping and vibration .
There is a lot of concern over the long term off gassing of spray foam. Google it, you'll get plenty of results, if done improperly the foaming agents can cause long term health issues. There is a lot of research still being done to determine the health effects.
There are formaldehyde free insulation options.
After an hour typing on my phone I'm done and I've done a quick poor job. Fiberglass isn't great either . Personally if I could get 1.5" rock wool batts locally I would have used that. Instead I went the well sealed Prodex route and good exterior maintenance. If you ever have to do repairs on the shell it will bite you in the back side.