Nasty Peeling Roof sos

[Andre3MC]

Our roof is gross! It is covered in some type dark of mold or moss and very cracked and peeling. Is the typical? Would pressure washing and hitting it with a wire wheel be appropriate for prep before applying Henry’s?

[Meathead]

It kinda looks like there is a coating on your roof already. The coating seems to end at the bottom of the lettering.

I don’t know. Sho is ugly tho![emoji50]

Have you tried chemicals?

[Andre3MC]

Originally Posted by Meathead

It kinda looks like there is a coating on your roof already. The coating seems to end at the bottom of the lettering.

I don’t know. Sho is ugly tho![emoji50]

Have you tried chemicals?

It could be some kind of coating, not sure. You can see the bird silhouette in the front still.

I haven’t tried anything on it, this is just how I got it. The ceiling is down on the inside and there are no apparent leaks.

[Meathead]

Henry’s makes silicone elastomeric and 100% acrylic. I have the acrylic. Mine is pretty dirty after just over a year. If mine were to sit under oak or pine trees for 8-10 years it would probably look like that. So yeah, I would start with pressure wash.

Some say that dirt gets into the silicone and you can never get it completely clean. But I don’t think you need to in order to recoat.

I will be washing and applying my 2nd coat soon so keep us posted.

Good luck.

[bus-bro]

I'd start by scrubbing it with tsp by a hand brush. After a good rinse you'd know what you got.

[Andre3MC]

I went up and smoothed the the roof surface with a wire wheel this weekend


After that we scrubbed it down with Krud cutter and a brush and most of the black stuff came off. It smelled nasty, I think it is some type of mold or moss.

The coating is a thick silicone like material and In really rough shape. I took off all of the loose material and smoothed it out the best I could, it is gauged down to the yellow bus paint or base metal in places now. If you leave the wheel in one place for more than a second it heats up and grabs, taking a lot of material with it. I don’t have the after pictures yet but it is much better and I think I will be able to go over it with Henry’s tropicool without too much trouble.

On a related note, I am preparing to patch the roof hatch with sheet metal to install a fan. I will be riveting and sealing with dynatron 550. What do you suggest for a material and thickness?

I am leaning towards 20 ga 304 stainless steel but might do 18 ga mild steel that I prime before install, what do you think?

Also I a vent In the roof at the front of the bus that let air out of the space between the ceiling and the roof, should I keep it or seal it up?


I am spray foaming and reinstalling the steel ceiling.

[musigenesis]

I removed my static vent in front because I suspected it as a source of leaking, but I took the vent apart afterwards and learned that it's actually really well-designed and won't allow any water through (even with high winds and rain) unless you fully submerge the bus. I wish I had left mine in place, but oh well.

Do you have spotted lanternflies where you are yet? The crud on your roof looks exactly like the lanternfly poop on my roof - they excrete this sugary substance that mold then grows in.

[shaymcquaid]

Why does everyone (myself included) use Henry’s Tropicool???
It SUCKS!!
Clean/paint/move on...

You’ll regret it if you do. I used the tan color at least��

[TheHubbardBus]

Originally Posted by shaymcquaid

Why does everyone (myself included) use Henry’s Tropicool???
It SUCKS!!
Clean/paint/move on...

You’ll regret it if you do. I used the tan color at least��

Yep. The heat-reflective properties are overrated. The color white is the real hero here, and it comes in urethane, enamel, & epoxy ;)

I also don't see much benefit to preventing leaks. If you have bad seams or rivets, covering them up with a rubberized coating is just putting a band-aid over the problem, which, like band-aids, will eventually come off. Or perhaps worse, delaminate & allow water to be trapped between the coating & roof, creating the perfect storm for corrosion. We were considering Henrys at one time. Based other's experiences as well as ECCB's advice we went the paint route. I'm really glad we did.

OP - Before applying ANYTHING, including Henrys, you really need to either get down to good paint (assuming there is good paint), or bare metal. Maybe even especially with Henrys, because the delamination scenario I mentioned above is probably all but guaranteed if you were to put it over what you've got now.

[musigenesis]

It seems possible that what's already on this bus' roof is Tropi-Cool (or a similar elastomeric coating), which would certainly seem like an advertisement for not putting more of it on.

[Andre3MC]

Originally Posted by musigenesis

I removed my static vent in front because I suspected it as a source of leaking, but I took the vent apart afterwards and learned that it's actually really well-designed and won't allow any water through (even with high winds and rain) unless you fully submerge the bus. I wish I had left mine in place, but oh well.

Do you have spotted lanternflies where you are yet? The crud on your roof looks exactly like the lanternfly poop on my roof - they excrete this sugary substance that mold then grows in.

Okay I may keep it then, it would save a bit of work.

I don't think we have those at all in NH but the bus came from Georgia so that could be it. In any case it is totally disgusting.

[Andre3MC]

I am really hoping that I can go over what is on there. I wouldn't try painting it because I doubt it would stick but I was hoping the Henry's would since it is similar. I would be fine with painting but as mentioned I would definitely need to remove what is on there and that would be an absolutely colossal task. It is thick, maybe an 1/8 inch and would be several weekends of work to get off with the wire wheel I would expect. Is removing it totally necessary if I am going with Henry's? If not how would you remove it?

The paint under looks fine and durable, except for the seams where it quickly rubbed down to bare metal on the edges and the top of rivets.

[musigenesis]

I found the pics from my disassembled static vent.





This humped piece inside prevents any rain from being blown directly through the circular hole in the bottom.



The hole itself has a raised lip all around which prevents any water that does get blown in from leaking down through the hole.







The key is to leave the channels in the four corners unobstructed so that any water that gets inside can immediately flow out. I've seen a few builds where people sealed these channels up, which would allow water to build up inside until it overflows the lip of the circular hole and goes into the ceiling.

I think this vent is a really cool little piece of engineering.

[Andre3MC]

We have decided to try to remove what is on there and use regular paint, I was hesitant to begin with using Henry's so this was convincing enough.

[TheHubbardBus]

I think you made the right decision.


Question about what's there, though. If it is old Henry's, & it's the silicone version (or if it's some other brand/type of silicone), does it come off any easier than silicone sealant would? Like completely off?

Paint will not stick to silicone, so if you don't get every bit off, your paint system is going to fail.

If it is silicone, and it's as resistant to coming off as I'd expect it to be, I'd think you'd have to strip the whole roof down to bare metal.


Not trying to give you headaches. Just want to make sure you don't invest a bunch of time, $, & effort only to end up w/ another mess.


I don't know if there are any reliable tests to determine if it's silicone. Maybe I'm just inexperienced and someone who knows can tell from look or feel. I do know that no common solvents (xylene, mek, etc) will dissolve it, but they will soften it. So if one of those solvents does dissolve it, it likely isn't silicone. But that's not the best test. 'dissolve' is subjective w/ cured sealants. And it could be a non-silicone sealant that's just resistant to whatever solvent you chose.


If it were me, I'd just take the whole thing down to metal, starting with cutting tools (scrapers, blades, etc) and then wire wheels / sanders. And then, I'd probably avoid putting down an expensive paint just in case you didn't get rid of it all.


Any rusting over the rivets / seams? A couple spots on our roof had large gobs of silicone sealant applied, and were rusted somewhat underneath where there was no rust anywhere else.


ETA: Any chance it's some type of external spray-foam insulation?

[Andre3MC]

Originally Posted by TheHubbardBus

I think you made the right decision.


Question about what's there, though. If it is old Henry's, & it's the silicone version (or if it's some other brand/type of silicone), does it come off any easier than silicone sealant would? Like completely off?

Paint will not stick to silicone, so if you don't get every bit off, your paint system is going to fail.

If it is silicone, and it's as resistant to coming off as I'd expect it to be, I'd think you'd have to strip the whole roof down to bare metal.


Not trying to give you headaches. Just want to make sure you don't invest a bunch of time, $, & effort only to end up w/ another mess.


I don't know if there are any reliable tests to determine if it's silicone. Maybe I'm just inexperienced and someone who knows can tell from look or feel. I do know that no common solvents (xylene, mek, etc) will dissolve it, but they will soften it. So if one of those solvents does dissolve it, it likely isn't silicone. But that's not the best test. 'dissolve' is subjective w/ cured sealants. And it could be a non-silicone sealant that's just resistant to whatever solvent you chose.


If it were me, I'd just take the whole thing down to metal, starting with cutting tools (scrapers, blades, etc) and then wire wheels / sanders. And then, I'd probably avoid putting down an expensive paint just in case you didn't get rid of it all.


Any rusting over the rivets / seams? A couple spots on our roof had large gobs of silicone sealant applied, and were rusted somewhat underneath where there was no rust anywhere else.


ETA: Any chance it's some type of external spray-foam insulation?

I have not encountered Henrys before or any other similar coating so it is hard for me to say. It is thick and very well adhered, I don't think scrapers or blades would work well. Once it got hot with the wire wheel it would cut right down to the yellow paint. I might try flap disk to get through it quicker. The bus paint seems really tough and in good shape so I hope I can paint on it. Maybe I can do a test patch somewhere first to see if it sticks well. So far I haven't seen any rust to speak of so I think I am good there.

[TheHubbardBus]

I don't know now. The thickness you speak of, it cutting down w/ a wire wheel once it got hot... sure sounds like it could be some kind of foam insulation. Wish we could see this in person. Can you cut a cross-section out? Does it look like a closed-cell product? I don't know enough about this kind of stuff to even guess if that's possible. But I do know our neighbor coated their (house) roof a few years back with a layer of external foam that had to have PO'd all the Karens. So I know it's 'a thing'. Maybe that's the same thing here??

Gotta be a knowledgable skoolie near you that could come take a look & probably give you an answer in seconds.


I guess if you've found a way to get it off & you're willing to go to the effort to get it all off, it doesn't really matter what it is. Like you said, you can do a spot adhesion test & adjust from there if you encounter issues. Good luck & happy new year. I look forward to seeing you're final product!

[Andre3MC]

Originally Posted by TheHubbardBus

I don't know now. The thickness you speak of, it cutting down w/ a wire wheel once it got hot... sure sounds like it could be some kind of foam insulation. Wish we could see this in person. Can you cut a cross-section out? Does it look like a closed-cell product? I don't know enough about this kind of stuff to even guess if that's possible. But I do know our neighbor coated their (house) roof a few years back with a layer of external foam that had to have PO'd all the Karens. So I know it's 'a thing'. Maybe that's the same thing here??

Gotta be a knowledgable skoolie near you that could come take a look & probably give you an answer in seconds.


I guess if you've found a way to get it off & you're willing to go to the effort to get it all off, it doesn't really matter what it is. Like you said, you can do a spot adhesion test & adjust from there if you encounter issues. Good luck & happy new year. I look forward to seeing you're final product!

I plan on pulling the hatch and getting ready to patch it tonight and tomorrow, I will try to get some more pictures and post them. It doesn't quite seem like a foam of sorts but I have never dealt with that either.

[Andre3MC]

Here is some that I hit with the wire wheel, it’s thinner than I remember

[TheHubbardBus]

I have absolutely no idea what that is. Not that I'm an expert (far from it).

Really hope someone chimes in w/ an answer.
Don't want to scare you, but your bus might have cancer