Drip rail leaks

[Tom and Erin]

Hopefully someone has a definitive answer. The drip rails along the bus sides above the windows have sealant in the gap at the top edge. Is this for cosmetic purposes only as it doesn’t appear to actually “seal” anything? Or stated another way, are the screws and screw holes the only source of leakage to the interior of the bus along the drip rails?

Thanks!

[Randy Dupree]

No sealant required to keep water out,but without sealant you can get dirt and leaves and stuff behind the drip rail.
There should be no place for leaks behind the drip rails.

[Debbie.Grey]

Originally Posted by Tom and Erin

Hopefully someone has a definitive answer. The drip rails along the bus sides above the windows have sealant in the gap at the top edge. Is this for cosmetic purposes only as it doesn’t appear to actually “seal” anything? Or stated another way, are the screws and screw holes the only source of leakage to the interior of the bus along the drip rails?
Thanks!

Mine were not suspect for an inside drip; I had a couple of streams of rainwater passing behind the drip rail and pouring across my windows.

We peeled the drip rail halfway back from one end and re-caulked it, gave it "set time", and repeated from the other end. Voila, dry windows. YMMV.

[Randy Dupree]

Originally Posted by Debbie.Grey

Mine were not suspect for an inside drip; I had a couple of streams of rainwater passing behind the drip rail and pouring across my windows.

We peeled the drip rail halfway back from one end and re-caulked it, gave it "set time", and repeated from the other end. Voila, dry windows. YMMV.

Debbie is correct!
I forgot about the wet windows!

[badandy]

The sheet metal screws that hold it on can leak, but it might not come through the spray foam on the inside of the wall. But they will leak. In my case they seem to just unscrew themselves over time, too.

[Bad Latitude]

What type of sealant is best for seams and screws?

[badandy]

Loaded question since it gets so hot up there. I haven't redone mine yet, but I like the idea of using butyl behind it and filling the gap on top with something like Sika Flex 221. Or skip the butyl and just use the 221 in the gap, but put a little blob of the 221 on the screw holes before putting the rail back on. Sometimes the butyl wants to keep squishing out over time, so it's not always the best thing to use because the screws loosen up, too.

[Tom and Erin]

Thanks all! Will check the screws, not getting the water through the window, fortunately.

[Bad Latitude]

Originally Posted by badandy

Loaded question since it gets so hot up there. I haven't redone mine yet, but I like the idea of using butyl behind it and filling the gap on top with something like Sika Flex 221. Or skip the butyl and just use the 221 in the gap, but put a little blob of the 221 on the screw holes before putting the rail back on. Sometimes the butyl wants to keep squishing out over time, so it's not always the best thing to use because the screws loosen up, too.

Thanks, I’m not familiar with those product but I’ll check them out. As a boat guy my go-to permanent and watertight sealant has been 3M 5200. I use it on under the waterline applications and have thought it would be overkill on the bus.

[Tom and Erin]

The only bad part about using 5200 is its relatively permanent bond. You can easily end up destroying things if you ever have to disassemble them. 4200 works just as well, but is not quite as hard to take apart. They also make a very UV resistant 4200UV. Neither is really optimal to use as a gap filling sealant however. They are more of a watertight structural adhesive or bedding compound.