Waterproofing Issues

[Ourversionoflife3]

Hey everybody. We're in the midst of sealing off water entry points to our bus and are getting stumped.

We've already done the obvious: Remove and reseal every window, put seam sealer on every seam and rivet on the roof, and removed the emergency hatches and put in Maxx Fans instead. There is no water coming in through any of the areas we've addressed, but we're seeing some water collect in an area we didn't anticipate.

It looks like water is collecting at the bottom of the side wall ribs where they meet the bottom shell of the body (the floor of the void between the outer body panels and the lower interior wall with the seat rail lip). We can't tell if the water is coming in through the body panel seems that attach to these ribs, or through rivets that attach the panels to these ribs, or both, or something totally different that we aren't seeing.

The water isn't getting to the main floor space but we don't want it in the void and creating mold on the insulation we plan to put in there.

Has anyone else seen this? What did you seal up to stop it and what type of sealant did you use?

Cheers,
Drew

 

[musigenesis]

Are you able to hang out in the bus when it's raining? Or even just be inside while someone runs a hose? The spot you're seeing water in likely means that one or more of your windows is still leaking (a few of mine are still leaking despite my sealing efforts, and the water either goes out onto the floor or into this cavity behind the chair rail, based just on where the little trickle happens to run randomly). If you're in the bus when it's raining, you should be able to spot the source(s) of the leaking pretty easily.

School bus windows can leak in a variety of different ways. The angle your bus is parked at may also affect which windows leak and where (my windows don't leak at all when the bus is parked flat, only when it's nose down and leaning to the left).

 

[Native-SKO]

In addition to what Musigenesis said, the angle of the water entry makes a difference.


I removed the windows (and their respective caulk) and reninstalled without any caulk ... from the four windows around the rear wheel wells. I have also removed the walls in that area (and the insulation inside the chair rail part of the wall there). Thus, I have great visibility as to what happens with water travel.


I have seen water enter through the widow sills and travel down the ribs to the floor. Sometimes, it will rain extremely hard and I'll not see any water entry at all. Other times the wind is blowing it just right and there is a little trickle stream.


I believe the walls are made to drain out. The insulation used is not organic and just sheds any water it collects ... eventually. It does tend to hold the moisture long enough to cause rusting problems though. I find that it is this rusting action that causes the water to redirect out onto the floor.

 

[Ourversionoflife3]

Well, I hope it’s just the windows still leaking. I thought I did a pretty thorough job of resealing, but I went out this morning after a light rain overnight and there was standing water on the inside of the sill on one window... And it was a pretty light and short rain.

It’s supposed to rain in a minute so I’ll try to sit in the bus and observe what happens. Also, I did use a silicone sealant thinking, “hey, it says 100% waterproof.” But now I’m learning that silicone isn’t really a good idea with metal surfaces. I may end up completely redoing the window sealing with a different product all together. I’ve heard Dynatron 550 is good.

 

[musigenesis]

there was standing water on the inside of the sill on one window... And it was a pretty light and short rain.

Sometimes the windows leak past the gasket around the edge of the glass pane itself; the water usually ends up where you describe. A little smear of Dynatron on the outside seems to stop it.

 

[Ourversionoflife3]

I sat on the bus through a rainstorm last night. I saw water collecting in the same spots at the bottoms of the ribs, but no absolutely clear sign of where it was coming from.

Today we tried an experiment. We sprayed a hose on the body panels on the outside of each rib, starting from the bottom and working the spray pattern slowly up towards the windows to see if water was coming in from beneath the windows. WOW. I could literally see water flowing in through the body in several of the rib areas. Not only was it coming through where the body panel seems are, but also in some areas where it’s only rivets!

The windows may or may not still need attention, but I think we’ve found the majority of the entry points below the windows. I got a tube of Dynatron 550 and I’m going to run it on every side panel seem and rivet and then repeat the test we did this morning. I REALLY hope this takes care of it.

Cheers.

 

[Ourversionoflife3]

Well, we put the Dynatron 550 in every place on the exterior side body where we thought water could be getting in. It's been a couple of rainy days since then and it looks like 90% of our water issues are now solved. We are only seeing water in the wall voids in one rib spot, and I'm pretty sure I see where it's coming from and should be able to take care of it the next dry day. So, it appears that our issues where mainly coming from the actual bus materials, not the windows.

There are definitely a few windows to reseal still, but we're only seeing minimal water along the window sills themselves.

I don't know if this is an issue specific to our bus, all Blue Birds, or all busses, but we were pretty surprised to have to go down this route. We haven't seen or heard anyone else describing a problem quite like ours before.

Really hoping we can move past the waterproofing this week and get to the fun stuff!