Spray foam insulation on walls, ceiling, and floor?

[Jshaul]

I'm looking at building a skoolie for full-time living in an RV park. I've ended up in the hospital from black mold in crappy apartments enough for this lifetime, and if I have to build my own, so be it!

Blown in closed cell foam (image link) looks like the right solution - it's stable, the R-value is high, it cuts noise, and - best of all - it's mildew resistant. DIY friendly, too. But I've never worked with the stuff, and am concerned about trapping moisture in a fashion that'd just make more mold and rust through the floor. The loss of headroom is worrying, too - regardless of bus, I don't really have the resources for a roof lift.

This bus will likely end up in the Southwest in 120F heat, and insulation is a big deal. Can anyone suggest how best to tackle this problem?

 

[2martins]

I'm looking at building a skoolie for full-time living in an RV park. I've ended up in the hospital from black mold in crappy apartments enough for this lifetime, and if I have to build my own, so be it!

Blown in closed cell foam (image link) looks like the right solution - it's stable, the R-value is high, it cuts noise, and - best of all - it's mildew resistant. DIY friendly, too. But I've never worked with the stuff, and am concerned about trapping moisture in a fashion that'd just make more mold and rust through the floor. The loss of headroom is worrying, too - regardless of bus, I don't really have the resources for a roof lift.

This bus will likely end up in the Southwest in 120F heat, and insulation is a big deal. Can anyone suggest how best to tackle this problem?

Green foam is I think the spray foam that I plan to use for the walls and ceiling but I am going with rigid for the floor because it seems a lot easier. You have to cut off the overspray which has got to be easier with the ribs as a guide. The floor has no ribs.

 

[Whatthefak]

Depends how tall you are man, I'm 6'4" I can't insulate without a roof raise even in a high roof bus but a guy 5'2" no prob

You could always spray a bedliner type product over your insulation to seal it, but it seems like over kill.

Keep the humidity down inside mold doesn't grow dry

 

[Twigg-SKO]

Depends how tall you are man, I'm 6'4" I can't insulate without a roof raise even in a high roof bus but a guy 5'2" no prob

You could always spray a bedliner type product over your insulation to seal it, but it seems like over kill.

Keep the humidity down inside mold doesn't grow dry

Closed-cell foam is already sealed.

 

[brokedown-SKO]

I've been calling around for estimates on spray foam and have been hearing much higher prices than I was expecting.... First estimate I got was $1500 for ceiling and walls (not including windows).

 

[peterbylt]

I've been calling around for estimates on spray foam and have been hearing much higher prices than I was expecting.... First estimate I got was $1500 for ceiling and walls (not including windows).

brokedown,
The guy that did my bus last year did an outstanding job, at half the price anyone else quoted, and operates out of St Petersburg, FL

Peter

 

[o1marc]

brokedown,
The guy that did my bus last year did an outstanding job, at half the price anyone else quoted, and operates out of St Petersburg, FL

Peter

And that price was?

 

[brokedown-SKO]

I remember your post about it, unfortunately there is no way I can get the bus to St Pete at this stage of the conversion! But your experience is what I'm comparing against.

 

[Jshaul]

Depends how tall you are man, I'm 6'4" I can't insulate without a roof raise even in a high roof bus but a guy 5'2" no prob

I'm 6' flat, so I could get away with some of the taller buses without doing a lift. The extra space would be nice, but I'm already at the limit of my mechanical ability. If I can find one with a lift for sale, I might buy it, but I'm not optimistic with my ~$5,000 budget.

Closed-cell foam is already sealed.

Yes, but the area over and around it? Homes usually breathe a lot better than cars, and I'm petrified of condensation collecting under the floor. I don't really understand home construction very well.

I've been calling around for estimates on spray foam and have been hearing much higher prices than I was expecting....

You can get DIY kits starting at $650. (I would say "How hard could it be?", but that always jinxes things...)

]The guy that did my bus last year did an outstanding job, at half the price anyone else quoted, and operates out of St Petersburg, FL

That is friggin' gorgeous.

Out of curiosity, how would you feel about living in your bus in Las Vegas, NV in July?

 

[Twigg-SKO]

Yes, but the area over and around it? Homes usually breathe a lot better than cars, and I'm petrified of condensation collecting under the floor. I don't really understand home construction very well.

You can get DIY kits starting at $650. (I would say "How hard could it be?", but that always jinxes things...)

The temperature of a surface relative to the temperature of a room will not be affected simply by trying to seal the foam. You have to address the issue with ventilation. having done your best to insulate and eliminate thermal bridges.

Condensation won't collect under the floor but it will collect on windows and any parts substantially colder than warm, moisture-laden air.

You will need at least two of those kits to insulate any decent sized bus. The DIT route doesn't save a great deal of money. It is cheaper, but you have to do all the work yourself and it still works out about twice the cost of foam-board. If you fit the board correctly, and seal the edges well, it will perform almost as well as spray-foam. Spray foam is superior, but at a price and the cost-benefit might be not be enough for you to commit the funds.

 

[ComfortEagle]

brokedown,
The guy that did my bus last year did an outstanding job, at half the price anyone else quoted, and operates out of St Petersburg, FL

Peter

It looks like your guy did a real nice job, how much? I presume the guy came to you? I should get some estimates but I understand that two of these kits is enough to do even a big bus. Aside from the pain of spraying it all, that's pretty affordable.

 

[jazty]

Aside from the pain of spraying it all, that's pretty affordable.

And the mess! Don't forget the mess because it's a big part of the DIY route. As you can see from the previously posted pictures, professional installs have very little waste and it fits the cavity almost perfectly. I 100% guarantee that the DIY kit run by a novice will waste upwards of half of the product which will run all over the place and need to be trimmed. For the round contours of the ceiling a grinder and wire wheel was about the only way I had on hand to trim the excess.. Such a mess. I wish I would have paid the extra $200 to have someone else do the job. It would have also been a better product. Professionals have the equipment to spray with the good stuff. The 2-part tank DIY stuff is just ok..

 

[Jshaul]

I wish I would have paid the extra $200 to have someone else do the job. It would have also been a better product. Professionals have the equipment to spray with the good stuff. The 2-part tank DIY stuff is just ok..

You've made your point. Guess I'll need to shop around for a pro.

You have to address the issue with ventilation. having done your best to insulate and eliminate thermal bridges.

I'm more concerned about summer condensation - cooling a 122F environment to 78 degrees causes a lot of mildew, even if it's somewhere dry like Arizona.

 

[Tall Grass]

You've made your point. Guess I'll need to shop around for a pro.



I'm more concerned about summer condensation - cooling a 122F environment to 78 degrees causes a lot of mildew, even if it's somewhere dry like Arizona.

Compare all this too solar panels on the roof and a painted white roof

 

[Jshaul]

Compare all this too solar panels on the roof and a painted white roof

I'm not looking at solar at the present - this is going to be used in an RV park pretty much permanently. The white roof is a must-have, though.

 

[PNW_Steve]

You've made your point. Guess I'll need to shop around for a pro.



I'm more concerned about summer condensation - cooling a 122F environment to 78 degrees causes a lot of mildew, even if it's somewhere dry like Arizona.

I have spent Summers in Las Vegas and Laughlin in a converted bus with spray foam insulation.

Condensation was NOT any issue at all. What little condensate there was from the A/C's went outside as it is intended to do.

Trying to maintain 78F inside when it was 122F outside was an issue.

My bus was painted "Arctic White" and had 2" of foam insulation. I had 2 x 12kbtu A/C's. When it was in the mit 120's outside I struggled to keep the inside temp below 90F. I had too many/ too big windows.

My intention with my new bus is to never be in 100F+ temps but I am still going to paint my bus white, insulate with spray foam, cover the roof with deck and solar panels to shade the roof and install smaller double pane windows.

To speak to your concern. I have lived in a converted bus in the kind of environment you described and had zero condensation or mildew issues.

I would suggest that you pay close attention to making sure your A/C condenser and condensate drains stay clean. If you do not then these could lead to mildew issues.

Good luck with your quest.

 

[Twigg-SKO]

Agree with this ^^^

When the RH is hovering between 2 and 5%, you can never get enough vapor in the air inside the bus for condensation to be an issue.

 

[Jshaul]

I have spent Summers in Las Vegas and Laughlin in a converted bus with spray foam insulation.

Condensation was NOT any issue at all. What little condensate there was from the A/C's went outside as it is intended to do.

Thanks for the detailed information!

I'm not sure what causes the endless black mold in Vegas, but it's good to know I haven't got it.

Trying to maintain 78F inside when it was 122F outside was an issue.

My intention with my new bus is to never be in 100F+ temps but I am still going to paint my bus white, insulate with spray foam, cover the roof with deck and solar panels to shade the roof and install smaller double pane windows.

Ah, yes. The other problem I was wondering about.

I have a rather Vegas-specific career in mind, so I'm stuck in the inferno. I am dismayed to hear you had this much trouble even with two air conditioners - I was only figuring on needing *one* of those.

It sounds like my original budget - which figured on plating over and insulating some of the windows, but no replacement with double-glazing or second A/C - is completely inadequate.

Back to the drawing board, I guess.

Agree with this ^^^

When the RH is hovering between 2 and 5%, you can never get enough vapor in the air inside the bus for condensation to be an issue.

That makes good sense - but where is all the @#$! black mold coming from?

You seem to have a good handle on home insulation design. Do you perhaps have a link to a good source on the basics?

 

[PNW_Steve]

"Where is all of the black mold coming from? "

Formation of black mold requires moisture. In LV if you have moisture issues it is most likely a plumbing issue or a dirty /plugged A/C evaporator.

If you have no water leaks and a well maintained A/C then you should have no moisture issues.

 

[Twigg-SKO]

Thanks for the detailed information!

I'm not sure what causes the endless black mold in Vegas, but it's good to know I haven't got it.



Ah, yes. The other problem I was wondering about.

I have a rather Vegas-specific career in mind, so I'm stuck in the inferno. I am dismayed to hear you had this much trouble even with two air conditioners - I was only figuring on needing *one* of those.

It sounds like my original budget - which figured on plating over and insulating some of the windows, but no replacement with double-glazing or second A/C - is completely inadequate.

Back to the drawing board, I guess.



That makes good sense - but where is all the @#$! black mold coming from?

You seem to have a good handle on home insulation design. Do you perhaps have a link to a good source on the basics?

If you want foam board, there is a bunch of stuff in my build thread, including why I chose XPS over Polyiso.

You can search the forum for Spray Foam