New day, same leak...narrowed down to roof seams!

[dbsoundman]

OK, I've done some reading, but I'm curious what the current thoughts are for tracking down and fixing roof leaks.

Basically, when I get a good steady rain or snow melt, I get leaks that appear below the windows, but only where there's a seam in the roof. I think this is partially because my bus is front engine, so it always tilts to the front, and all of the roof panels overlap going toward the rear of the bus. Visually from the ground the seams look fine, but evidently they're not, because I've sealed just about every other d*mn thing and still haven't found the issue. Most recently, I sealed along the top of my rain gutters. The fact that the leaks only occur where there are roof seams was my "lightbulb moment" today.

All that being said, there are two potential areas of concern with these roof seams: the actual seam between the two pieces of sheet metal, and alllllll of the rivets holding the two panels together. I'm inclined to think that sealing the seams between the sheet metal will do it, but I've been wrong...too many times at this point.

In one thread EastCoastCB said that he planned to tape off each seam about 3/16" on each side, run a bead of Dynatron 550, and peel off the tape. I've found that Dynatron is nice because while it is VERY sticky, it also gives you a lot of working time, so I'm inclined to go that route, though I may go for the Dynatron 570 if I can find it (white instead of gray). I don't think I'm interested in going the Tropicool route, plus I need to fix this sooner rather than later and it's cold here, so doing any work will be tricky - pray for 40 degrees and sunny!

Any other recommendations based on your experiences would be super helpful!

[dbsoundman]

Replying to my own thread...what about Eternabond tape? Not sure how it would look but I'm wondering if it would be less error-prone than Dynatron?

[Rucker]

Originally Posted by dbsoundman

Replying to my own thread...what about Eternabond tape? Not sure how it would look but I'm wondering if it would be less error-prone than Dynatron?

Eternabond looks crappy. I have some covering the brackets that hold my solar panels and I'm less than happy with the look, even though it's a good product for leaks.

[peakbus]

I found Dicor lap sealant to be good, but can be messy if you want to tool it smooth. The self leveling type is good for flat areas but don't use if on the curves or it will probably end up in your rain gutters.

[musigenesis]

Originally Posted by dbsoundman

In one thread EastCoastCB said that he planned to tape off each seam about 3/16" on each side, run a bead of Dynatron 550, and peel off the tape. I've found that Dynatron is nice because while it is VERY sticky, it also gives you a lot of working time, so I'm inclined to go that route, though I may go for the Dynatron 570 if I can find it (white instead of gray).

I second this approach. I did the same preemptively when I first got my bus and I've had absolutely no leaks through the roof seams. I don't think there's any way these seams could possibly be watertight without sealant, especially when the bus is nose-down as you say. I would add that it's important to clean the areas really well and scuff them with sandpaper before applying the sealant. Also, misting the sealant with mineral spirits can extend the working time considerably and allow you to make a really smooth seam (and make sure you pull up the tape before the sealant sets). I used Dynatron-550 (the gray stuff) and I do wish I'd used 570 instead, but I'm eventually going to paint over the gray seams when I get around to it and it shouldn't be more than an afternoon's work, if that.

[dbsoundman]

This looks promising! Any votes for seam sealer from a can?

https://youtu.be/KysXj_PfIAE

The use of prep spray is the real magic. No doubt analogous to acetone.

[peakbus]

Originally Posted by dbsoundman

This looks promising! Any votes for seam sealer from a can?

https://youtu.be/KysXj_PfIAE

The use of prep spray is the real magic. No doubt analogous to acetone.

Wow, I like the magic spreading spray!

[musigenesis]

Originally Posted by dbsoundman

This looks promising! Any votes for seam sealer from a can?

https://youtu.be/KysXj_PfIAE

The use of prep spray is the real magic. No doubt analogous to acetone.

Mineral spirits in a spray bottle will do the exact same thing to Dynatron-550.

[dbsoundman]

Friend of mine that does auto body work recommended SEM seam sealer, I might just give it a go.

https://www.semproducts.com/product/...-sealers/29362

[musigenesis]

Originally Posted by dbsoundman

Friend of mine that does auto body work recommended SEM seam sealer, I might just give it a go.

https://www.semproducts.com/product/...-sealers/29362

I can vouch for their self-etching primer, at least.

[dbsoundman]

Originally Posted by musigenesis

I can vouch for their self-etching primer, at least.

Yeah. It's about $5 more per tube than Dynatron 550, but then again I'd be wanting Dynatron 570 (white), which is...the same price as SEM's white sealer.

Just curious if SEM is less sticky, Dynatron really seems to be geared toward panel bonding, based on my experience trying to use it to seal up the outside of my windows.

[musigenesis]

Originally Posted by dbsoundman

Yeah. It's about $5 more per tube than Dynatron 550, but then again I'd be wanting Dynatron 570 (white), which is...the same price as SEM's white sealer.

Just curious if SEM is less sticky, Dynatron really seems to be geared toward panel bonding, based on my experience trying to use it to seal up the outside of my windows.

I think the 'tron is sticky because of the amount of solvent in the goop. When you mist it with mineral spirits, it gets a lot less sticky and more pliable.

I'm sure the SEM sealer is just as good, and it's probably easier to find than Dynatron-570.