I still consider these windows an upgrade from the standard school bus issue, but I have found them to be quite drafty and I’ve also found that they can leak to the inside of the wall where you can’t actually see the leak. Fortunately my bus is from a very arid part of the country where if it does rain or snow it doesn’t amount to much, it dries quickly and stays dry for a long time. Not so in Wisconsin where the bus now resides. The bus is, for all intents and purposes, rust free, but I don’t think it would remain so much longer if I do not take action.
Every wall section that I’ve opened so far has water in the bottom of the chair rail and the rubber, foam backed, sound deadening layer covering the firewall at the very back of the bus is saturated with water that’s leaking in from the passenger side window at the very back of the bus.The lower portion of that sound deadening material is so saturated that it is constantly releasing water onto The stitch-welded seam where the floor meets the wall that separates the interior of the bus from the engine compartment.
I believe that the floor is galvanized but the welds that join the two sections have never been painted or protected in anyway and as I said the welding is not continuous so I’m sure that the juncture of the two panels is sucking up as much water as capillary action will allow. I am eager to get some insulation on the floor, but it cannot happen until the moisture problem is solved.
I am getting ready to take six windows out as part of my overall conversion plan, so I think I will learn a lot about the windows as I get to see their construction a little more closely. I’m hoping I’ll find some solutions to the leakage problem that I can apply to the remaining windows. And of course, six windows removed are six windows that can’t cause me any more trouble.
As far as the draftiness goes, The first thing I’m noticing is that these are egress windows, by which I mean that they are meant to act as escape routes in the event of some emergency. They are hinged at the top and have a release handle on the side that allows them to swing out so passengers can escape or rescuers can enter. this means there are basically two frames, a frame within a frame, and double the number of potential leaks. I am not aware of any weatherstripping in any of this, and there are places where I can see daylight between the outer frame and the inner frame. I am probably going to have to disable the escape hatch function of the window by sealing the inner frame to the outer frame with some kind of adhesive caulk. I think that will go a long way towards tightening up the unwanted airflow.
Also, I’m pretty sure these windows are supposed to be sliding windows that can be opened, at least partially, but so far they seem to be locked down to prevent opening. Either that or they’re just jammed. The bus has maximum air-conditioning so they may have not wanted the windows to open, but I will certainly want to be able to open at least some of the windows to allow fresh air to enter when conditions are such that that would be enjoyable.