Spray foam and temperature?

[PNW_Steve]

Hey Everyone,

I had really hoped to get to the point where I was ready to spray foam insulation before it turned cold. Too late...

We are seeing high 20s to low 30s at night and around 50 during the day.

Has anyone here had any experience with trying to heat the inside of the bus to allow spraying the foam at correct temperatures?

I considered using my propane heater but I am afraid that it will add too much moisture.

I have a 3500 watt portable electric heater but cannot find an extension cord (NEMA 15-30).

I am considering buying a 120v portable heater and see how that works.

Thoughts or suggestions?

Thanks

[Drew Bru]

We just got a Chinese diesel heater and have been using it for the past few days. It's getting into the teens and twenties here at night and we've been at a comfortable 55 degrees at night, on a low-ish setting. A gallon of fuel lasts through the night.

[Native]

Originally Posted by Drew Bru

We just got a Chinese diesel heater and have been using it for the past few days. It's getting into the teens and twenties here at night and we've been at a comfortable 55 degrees at night, on a low-ish setting. A gallon of fuel lasts through the night.

This does seem like the way to go for heating a bus shell as long as it is not extremely cold. We have run a ceramic space heater (1800 watts @ 120V) and it does only a little more than chase the chill away.

[family wagon]

I think you're right to worry about moisture. Any fuel-burning heater will increase the humidity inside the bus; it'll quickly lead to condensation which will prevent the foam bonding to the metal.

Check with your insulation supplier, but.. I wonder, is 50° F still adequate for foaming? If you could park the bus in the sun and work in the early afternoon the surface temperature on the sun-facing side might be even warmer.

The big problem is that you need warm metal more than you need warm air. If it's cold outside then I guess you'd need a lot of heat inside in order to get the metal surfaces warmed.

Maybe you could use the old trick for thawing frozen water pipes. Hook up one clamp of a stick welder to each end of the bus and let the current warm it for a while!

[PNW_Steve]

Originally Posted by family wagon

I think you're right to worry about moisture. Any fuel-burning heater will increase the humidity inside the bus; it'll quickly lead to condensation which will prevent the foam bonding to the metal.

Check with your insulation supplier, but.. I wonder, is 50° F still adequate for foaming? If you could park the bus in the sun and work in the early afternoon the surface temperature on the sun-facing side might be even warmer.

The big problem is that you need warm metal more than you need warm air. If it's cold outside then I guess you'd need a lot of heat inside in order to get the metal surfaces warmed.

Maybe you could use the old trick for thawing frozen water pipes. Hook up one clamp of a stick welder to each end of the bus and let the current warm it for a while!

I checked with the foam supplier and they want 70F or higher. I am contemplating running a new 220v circuit out by the bus and running my "portable" 220v heater in the bus overnight to get the bus "heat soaked". I need to find out if I can leave the heater running while I spray.

[Sleddgracer]

Originally Posted by PNW_Steve

I checked with the foam supplier and they want 70F or higher. I am contemplating running a new 220v circuit out by the bus and running my "portable" 220v heater in the bus overnight to get the bus "heat soaked". I need to find out if I can leave the heater running while I spray.

probably not while they are spraying - the fumes are explosive

[BarnYardCamp]

what about combustible fumes? I don't know if that would be a issue or not.
certainly something to consider before you use a heater that could ignite it.

[family wagon]

If it's one of those oil-filled radiator types it should be fine to run while spraying, but if it's a hot wire and fan type heater, I'd be worried about ignition potential. Either way you'll probably get foam overspray on or even in the heater.



If there's any way you could borrow or rent concrete blankets to cover the bus that would go a long way toward raising the temperature of the sheet metal. Even just uninsulated tarps might help.


It's worth measuring the temperature of the metal on the sun-facing side of the bus in the early afternoon. I'll bet it's warmer than the air temperature, though maybe only by 10 degrees.

[Biscuitsjam]

Spray foam is expensive. It's also difficult to fix if you screw it up. My thought is you should wait 6 months on the spray foam.

If your bus is like mine, there are hundreds of little projects that need to be done. Pick some of the others and get back to this one when it's warmer.

I'm planning to drive down the ALCAN in January, but I haven't spray foamed yet... I missed my chance...

[musigenesis]

Originally Posted by PNW_Steve

Hey Everyone,

I had really hoped to get to the point where I was ready to spray foam insulation before it turned cold. Too late...

We are seeing high 20s to low 30s at night and around 50 during the day.

Has anyone here had any experience with trying to heat the inside of the bus to allow spraying the foam at correct temperatures?

I considered using my propane heater but I am afraid that it will add too much moisture.

I have a 3500 watt portable electric heater but cannot find an extension cord (NEMA 15-30).

I am considering buying a 120v portable heater and see how that works.

Thoughts or suggestions?

Thanks

The first bunch of skooliers I went to help back in February were painting their bus in New Jersey. They had bought the bus from a bus services company (that decided to sell off their old buses to skoolie builders instead of just scrapping them) and this place rented them one of their inside (heated) work bays for the weekend (Saturday and Sunday). They paid $100 or $200, I forget which, but if you could find something like that, the extra couple of hundred seems pretty small compared to the price of the spray foam. Maybe you could even paint your bus in the same weekend.

I think if you're trying to heat the inside sufficiently, you're going to run into problems because the skin of the bus is still going to be closer to the outside temperature than your inside temperature, and that foam will be right up against the skin.

[Ghrasshopper]

I would have to agree with biscuits there. Spray foam is expensive and sensitive. If you can’t find somewhere heated to do it I would wait until it warms up. I just did mine and my spray foam manufacturer also recommended wrapping my tanks in an electric blanket or putting heating pads in the box they came in for a couple of days prior to spraying to ensure the tanks themselves were warm enough. Also from my experience if you are going to put any furring on the ceiling I recommend you do that and seal them before you spray. Also the metal has to be prepped well and really clean or the foam won’t adhere to it. I had a tar coat on my roof and a “coating specialist” friend of mine recommended getting a good primer on my ceiling so the foam can solidly adhere to something. Those are my thoughts on the subject. I hope your project goes well.

[PNW_Steve]

Thanks for the input.

I talked to the folks supplying the foam and the fumes are not flammable and they recommend placing a heater blowing on the tanks.

I am going to put my heater out there and see how warm I can get it.

[Sleddgracer]

Originally Posted by PNW_Steve

Thanks for the input.

I talked to the folks supplying the foam and the fumes are not flammable and they recommend placing a heater blowing on the tanks.

I am going to put my heater out there and see how warm I can get it.

having almost becoming involved in that industry when Canada was giving subsidies to home owners who retro-insulated their houses with spray foam and about to take on my first contract which was also a large one, I was told by the local fire chief that he would not issue a permit because of the fire hazard that spray foam presents - spray foam itself does not burn, but when being applied or heated after installation, the vapours are explosive - insurance won't cover spray foam for those reasons unless the foam is covered with drywall or some sort of covering - look at what the ingredients are - urethane for one thing, is HIGHLY flammable - I was lucky that things came together the way they did at that time - had I been caught up in the retro -foam industry, I could well have lost my house - once the off-gassing came to light, every thing/every one that had anything to do with insulating a house was sued, including the federal government

[PNW_Steve]

Originally Posted by Sleddgracer

having almost becoming involved in that industry when Canada was giving subsidies to home owners who retro-insulated their houses with spray foam and about to take on my first contract which was also a large one, I was told by the local fire chief that he would not issue a permit because of the fire hazard that spray foam presents - spray foam itself does not burn, but when being applied or heated after installation, the vapours are explosive - insurance won't cover spray foam for those reasons unless the foam is covered with drywall or some sort of covering - look at what the ingredients are - urethane for one thing, is HIGHLY flammable - I was lucky that things came together the way they did at that time - had I been caught up in the retro -foam industry, I could well have lost my house - once the off-gassing came to light, every thing/every one that had anything to do with insulating a house was sued, including the federal government

I am inclined to take the manufacturers advice. I doubt they would tell me that they recommend running the heater while spraying if the fumes are flammable. In fact they told clearly "the fumes are NOT flammable."

I had my first bus spray foamed. I moved into it full time about two months later. I lived in that bus for 7+ years. I did not have any issues with offgassing.

That said.... I am reconsidering having it done professionally. Unfortunately the outfit that does it here wants almost $1900 to do the walls and ceiling. None on the floor. I'm using sheet foam on the floor.

[Sleddgracer]

Originally Posted by PNW_Steve

I am inclined to take the manufacturers advice. I doubt they would tell me that they recommend running the heater while spraying if the fumes are flammable. In fact they told clearly "the fumes are NOT flammable."

I had my first bus spray foamed. I moved into it full time about two months later. I lived in that bus for 7+ years. I did not have any issues with offgassing.

That said.... I am reconsidering having it done professionally. Unfortunately the outfit that does it here wants almost $1900 to do the walls and ceiling. None on the floor. I'm using sheet foam on the floor.

at the time I was involved with spray foam, the manufacturers claimed zero flammability too - they didn't mention how critical the mixture had to be, the off-gassing, or that the gasses given off by heated spray foam were explosive - go ahead, but an open flame or heated element in your bus when it's being sprayed is at the risk of lives - I went through the whole rig-a-ma-roll at one time and thought I could spare you some heartache and perhaps your life - I'll be spray foaming my bus too, but I won't take foolish chances with open flames or hot elements - I suggest you check what your local fire department has to say about it - they have no stick in the fire, and are, or should be, up to date on the subject

[PNW_Steve]

It would only take one customer to blow themselves up for a big lawsuit / settlement against them.

The point may be moot. At 10:30 this morning it was 36F outside. I can't wait six months so I am reconsidering having it done professionally. I hate spending the extra $600 but I starting to lean that way..

[Firepuncher]

Originally Posted by Sleddgracer

having almost becoming involved in that industry when Canada was giving subsidies to home owners who retro-insulated their houses with spray foam and about to take on my first contract which was also a large one, I was told by the local fire chief that he would not issue a permit because of the fire hazard that spray foam presents - spray foam itself does not burn, but when being applied or heated after installation, the vapours are explosive - insurance won't cover spray foam for those reasons unless the foam is covered with drywall or some sort of covering - look at what the ingredients are - urethane for one thing, is HIGHLY flammable - I was lucky that things came together the way they did at that time - had I been caught up in the retro -foam industry, I could well have lost my house - once the off-gassing came to light, every thing/every one that had anything to do with insulating a house was sued, including the federal government

Can you say UFFI????? I lived through that ugh.


S.

[Sleddgracer]

Originally Posted by Firepuncher

Can you say UFFI????? I lived through that ugh.


S.

it wasn't pretty and I'm glad I had escaped being involved with it by the skin of my teeth

[Neorush]

I am not a professional but have worked with them many times doing spray foam jobs. The off gasses are not flammable (but quite toxic to breathe). But the foam absolutely is, even with the fire retardant in the mix. Having tiny droplets of foam flying out of a gun (already in excess of 120F) around a heat source is very dangerous.

That said, the biggest problem you have is moisture. The foam is an exothermic reaction, so it immediately heats up any surfaces it touches as it's curing. If there is cold air on the other side of the surface it will cause rapid condensation. This will stop the foam from sticking to the surface, and also not expand properly since the cool surface sucks heat from the reaction. Industry standard is 60F-90F substrate surface temperature, NOT ambient air temperature. It is going to be very very hard to get the metal surface above 60F when the air outside the bus is below 40F.

I live in a cold climate and they charge $0.90 per sqft per inch around here. That is basically the same price as a foam kit. Having seen this done multiple times properly I would pay a pro to do it. The guys I use also included trimming and clean up in the price, which they have all the tools to make trimming look easy. On top of that, if it gets messed up, they'll come pull the bad foam and redo it.

[Bon Voyage]

I got mine professionally done as I found a guy to do it for the same price as buying the foam myself. He wouldn’t do it when it was cold because he said it wouldn’t adhere properly. My bus wouldn’t fit in his shop and I tried to find a shop that would let me do it inside but nobody would for a reasonable price. I think it was close to 60 degrees outside when he did it and it seems to be fine. Heating the interior wouldn’t have heated the walls enough.