A Bus Named Sandy

[Bpjr07]

That's one cool bus!!!
Are those rV windows?

[TeacherJoe]

Originally Posted by Bpjr07

That's one cool bus!!!
Are those rV windows?

Thanks. We do love it. Yes, those are RV windows. That was the good news. We bought it with a professional inspection down south. He didn't notice the bad news: none of the windows would open. We tried everything. Good news: new windows arriving Thursday.

Joe

[TeacherJoe]

After playing with foam board on the ceiling, we've decide to do DIY spray foam insulation. We were willing to pay a pro, but the lowest price I got is $1500. Even though we have around 200sf of ceiling and wall, we're going to buy a 600sf kit.

Questions:
Do I need to spray inside the ribs? I have starter screw holes left from the demo. I was picturing expanding the holes, say every foot, and spraying Great Stuff in there.
I will spray behind the lower wall. Do I need to treat the metal face of the wall with Reflectix or something else?

Joe

[o1marc]

Originally Posted by TeacherJoe

After playing with foam board on the ceiling, we've decide to do DIY spray foam insulation. We were willing to pay a pro, but the lowest price I got is $1500. Even though we have around 200sf of ceiling and wall, we're going to buy a 600sf kit.

Questions:
Do I need to spray inside the ribs? I have starter screw holes left from the demo. I was picturing expanding the holes, say every foot, and spraying Great Stuff in there.
I will spray behind the lower wall. Do I need to treat the metal face of the wall with Reflectix or something else?

Joe

The 600sf kit is at 1" thick, you'll want to go 1-1/2"-2" requiring more of the kit than you think. My rib are filled with batt insulation, shooting Great Stuff in there would be a waste of time and effort for minimal advantage if any.

[david.dgeorge07]

Filling ribs is nice idea, but doubt that it nets much. Facing the ribs with something is probably quite worthwhile. Filling doesn’t create a thermal break, while facing the rib will.

[TeacherJoe]

Originally Posted by david.dgeorge07

Filling ribs is nice idea, but doubt that it nets much. Facing the ribs with something is probably quite worthwhile. Filling doesn’t create a thermal break, while facing the rib will.

What would you recommend?

Joe

[HazMatt]

I'd thought, at the outset of conversion, the idea of filling the ribs was a jim-dandy idea. Then I started studying on it:
Filing in the void will do little to abrogate thermal bridging, since it's the metal that's conducting heat. GreatStuf is not a great option in our application as it's an open-cell foam, so it can collect water, and accelerate rusting.
There are probably as many schools of thought as there are Skoolies. I went with wooden furring strips mounted to the hat channel's sides after glueing insulating foam board to the ceiling. Followed by an air gap, then Reflectix lightly stapled to, and luaun panels screwed into, the furrs.

[TeacherJoe]

Originally Posted by HazMatt

I'd thought, at the outset of conversion, the idea of filling the ribs was a jim-dandy idea. Then I started studying on it:
Filing in the void will do little to abrogate thermal bridging, since it's the metal that's conducting heat. GreatStuf is not a great option in our application as it's an open-cell foam, so it can collect water, and accelerate rusting.
There are probably as many schools of thought as there are Skoolies. I went with wooden furring strips mounted to the hat channel's sides after glueing insulating foam board to the ceiling. Followed by an air gap, then Reflectix lightly stapled to, and luaun panels screwed into, the furrs.

Sounds like a good approach. However, everything I read says Great Stuff is closed cell.

Joe

[EastCoastCB]

Originally Posted by TeacherJoe

After playing with foam board on the ceiling, we've decide to do DIY spray foam insulation. We were willing to pay a pro, but the lowest price I got is $1500. Even though we have around 200sf of ceiling and wall, we're going to buy a 600sf kit.

Questions:
Do I need to spray inside the ribs? I have starter screw holes left from the demo. I was picturing expanding the holes, say every foot, and spraying Great Stuff in there.
I will spray behind the lower wall. Do I need to treat the metal face of the wall with Reflectix or something else?

Joe

I wouldn't spray into the inside of the ribs. Never use "great stuff" on your bus. Its corrosive to metal when enclosed.
Reflectix is just mylar and bubblewrap please save your money.

[Shorty22]

I agree, I've researched the Great Stuff product for skoolies (many threads on this site) and the most compelling argument against filling ribs with spray foam is that you should never spray into something that you cannot see inside of. The material needs a lot of airflow to set, and harden the material. Also, Great Stuff when used in homes, people have complained that it turns into a green goopy mess after some age.

As for reflectix.. I know in green building standards, a radiant barrier in the roof only works when there is a 1" air gap behind the "reflectix" type material. This allows the material to do its job in blocking the UV radiant heat. So, if the reflectix material is just an added layer jammed in somewhere, it will not do the proper job of keeping the heat out or in because it needs air space/ pathway for the heat to otherwise go.

I have a large roll of 1/4" cork underlayment that is leftover from my subfloors. I will be attaching this to the metal skin interior of the bus with construction adhesive, then adding 3" rockwool insulation between the ribs + 1 1/2" wood strips on the metal ribs to increase the cavity space for the insulation to fit + use this to attach my studs into.

[juliol]

I know foam insulation is the best, but I have been testing reflectix and notices something while looking at the bus from my window at night, look at the pictures, I circled the area of regard on the roof, the circled area ins the only area that I installed reflectix on the ceiling, what does it mean other that the obvious?

[Shorty22]

Originally Posted by juliol

I know foam insulation is the best, but I have been testing reflectix and notices something while looking at the bus from my window at night, look at the pictures, I circled the area of regard on the roof, the circled area ins the only area that I installed reflectix on the ceiling, what does it mean other that the obvious?Attachment 36036

Attachment 36037

I assume you are talking about discoloration? I do't know lol it could be the heat trapped inside the bus from a hot day, keeping that square warmer, and the rest of the bus could be lighter in color if it is a cold night and developing some sort of frost on the shell?

[david.dgeorge07]

If you can spare the headroom I would face the ribs with a thin layer of some sort of foam. Like maybe 1/4” closed cell sheet. Make it as thick as you can spare, but even an eighth of an inch would likely help with condensation issues you will get from the bare metal.

[Shorty22]

Structurally, I would not add foam insulation between the metal ribs and the wooden studs.
As for the rest of the areas, like the metal ribs to the wooden paneling in the interior ceiling, it should be OK with foam board insulation in those areas.
Most builds include wood “furring strips” all along the ribs to help with thermal bridging. This makes a secure anchor point for the studs.

[TeacherJoe]

Originally Posted by Shorty22

Structurally, I would not add foam insulation between the metal ribs and the wooden studs.
As for the rest of the areas, like the metal ribs to the wooden paneling in the interior ceiling, it should be OK with foam board insulation in those areas.
Most builds include wood “furring strips” all along the ribs to help with thermal bridging. This makes a secure anchor point for the studs.

Here’s what my ceiling looks like at the moment.

Joe

[HazMatt]

Not for nuttin'...
Using the laser thermometer to check temps on the unfaced Reflectix to an immediately adjoining area sheathed only in 1/2" foam insul-board shows a 10-18° degree (cooler) difference.
Mylar coated bubble wrap is NOT an expensive scam, if installed correctly.
Just my empirically observed opinion...
As to my take on the thermal bridging issue:
Never mind- "You do not have permission to post attachment in this forum."
Too bad, and not only for the ungrammatical nature of that notice...

[o1marc]

If checking temps with a temp gun, if shooting at the foil face, it will not give you an accurate reading.

[TeacherJoe]

We got the first three windows in today. Really, not too hard. These are from Motion Windows.
Joe