Coating the Roof

[Cozimoto]

I've searched to see if this has already been covered and didn't quite find my situation-

My Chinook was painted (or gel coated?) a dark blue color making the rig very warm when in sunny locations, some of the paint (or gel coat) is peeling on the top exposing the old fiberglass and some small cracks. I want to use some readily available roll on waterproofing/sealant to help cool things off and add a layer of protection to the roof. Has anyone done this and have thoughts on products? It's an old rig so I'm not going to get some expensive commercial paint job, needs to be a do-it-yourself product.

[Blue~Go]

I have to start out by saying I haven't done this exact thing. I've only painted fiberglass (boats, not my Chinook). I can certainly understand why you'd want to deal with peeling, dark paint. How hot that must be.

I'd be surprised if it's gelcoat. Not that you couldn't spray gelcoat over an entire Chinook but it's 90% likely to be paint.

I think if I were wanting to do something like this I'd proceed something like this:

.5) Remove as many things from the roof as possible (vents, AC, etc.). Good time to re-bed them (afterward) and they won't be in your way while prepping and coating.
1) Remove all dark paint (or at least the poorly adhered stuff which is probably most of it) so you are back to the gelcoat.
2) Prep how maybe they didn't to begin with (hence peeling), starting with removing the mold release wax that makes for poor adhesion to molded gelcoat (202 Solvent wash, giant stack of clean rags). I know, it's 20+ years old, but the mold wax is forever until you purposefully remove it.
3) Fill or repair any damaged areas (not saying there will be any).
4) Sand entire thing for tooth.
5) Clean with whatever solvent the coating mfgr. recommends.
6) Re-coat with.... I'd probably look into Line-X, Monstaliner, or something like that. They are texturized paints that sound fairly forgiving, and are appropriate for fiberglass (vs. sealants meant for rubber or house roofs). Obviously use a light color!
7) Re-install all the roof stuff you removed, bedding with something good (Bed-It for example). The Air-con though only has a squishy foam gasket - no sealant.
8) Enjoy your cool, non-peeling roof!

[kdarling]

With the Chinook single piece fiberglass shell, there's no reason to add to top weight and thickness with any kind of sealant paint... unlike many other RVs with segmented roofs.

So I'd instead concentrate on finding a cost effective heat reflective paint.

If it were me, I'd also probably go for a pale blue instead of white, to better match the dark blue sides.

While white can drop the surface temperature by 60 degrees (e,g. 140 down to 80), a light blue will still drop by 45-50 degrees.

Just some thoughts,
Kev

[Cozimoto]

Thanks for the replies, I might do a test area where the paint has already peeled and see how that turns out, I'll have to look into the products suggested. I was actually thinking if I could get something that was tint-able I would make it a light gray to go with the coaches trim color.

[Blue~Go]

Agreed, no need to "seal." Line-X and Monstaliner are no doubt heavier than just plain paint, but I don't think they are massively heavier. They are heavily texturized paint type product. Places like Sportsmobile coat their fiberglass tops with it (probably to avoid having to finish them perfectly, and/or to cover up tiny gelcoat cracks). And many of those are lifted by hand (with helper springs, but still). Also they will give you a little bit of non-skid up top.

But you could also use "just" paint, It will be lighter weight, which is a plus, but won't cover flaws or be "forgiving" for DIY in quite the same way. But that might not matter to you. As a side bonus with either type of coating, you won't get any of the white streaking that sometimes can occur if a white fiberglass roof is oxidizing (when it rains). 'course I guess with a painted roof you aren't getting that anyway (you get blue paint ribbons....).

[Cozimoto]

A cousin in Florida mentioned "Kool Deck" but that appears to be a coating for cement around a pool, not sure I need all that, seems like simple paint is the way to go .... would you suggest an Automotive Paint??? any pointers on type (or brand) of paint I should use?

[Blue~Go]

I wouldn't use any of those pool/roof/basement/whatever coatings.

I'd probably choose something like Line-X or Monstaliner. I have not used those (they don't really get used on boats), but I have read good things about them from people who have coated their (entire) vans with them. Also Sportsmobile roofs, which are fiberglass roofs. They seem to stand up to the test of time, and they seem DIY friendly.

For a paint, I think the best way would be a two part such as Awlgrip, Sterling, or etc. However those do have a learning curve, and you can't spray them without supplied air (a regular passive respirator is not enough; these things are toxic while wet). You can roll/tip them with a regular respirator though (because you are not aerosolizing them like you are with a sprayer).

There are also one part paints such as Interlux Brightside, and Petit Easypoxy. Contrary to labeling these are not really epoxies, but are modified alkyd paints. Easier to apply than two-part, and cheaper. The downside is they are softer and the shine won't last nearly as long (say two years vs. fifteen or more).

With a shiny coating you may want to add some non-skid additive, at least for your walkways (Line-X or Monstaliner are already non-skid).

The main thing is going to be the prep. My guess is that whomever painted it before did not remove the mold release wax, or did a poor job of it (like using the same rag to go over the next section vs. a new one), and or a poor prep job in some other way. That will cause most any coating to have adhesion problems.