How to seal Leaking Windows?

[musigenesis]

Twice now since I removed all my windows, cleaned and resealed them, I've had a major leak appear in a window and then go away on its own. I don't really understand how that could happen unless they're little pinholes that eventually get stopped up with grime from the roof runoff.

[JDSquared]

I watched a build thread on YouTube where they kind of balled up the butyl tape so it was twice as thick. I think it was bussy mcbusface. If not I would still recommend watching their build videos.

Water is tricky. It will find a way if it can. Shine a flashlight in the pitch dark and look for pinholes maybe. Check your entire window top to bottom for it's coming in. It could be running down inside your ceiling from someplace too and showing up in your window.

[Marceps]

For what it's worth, the flashing on my Thomas fails to adequately cover corners. This seems to be a design flaw.

I am no longer able to inspect this.

[Sevier]

Originally Posted by tobeamiss

It did, but a couple of Windows still leak. I guess I wasn't thorough enough on them. It could have been late and I could have been tired....you know, 20 Windows.....
At first, most of my Windows leaked, and now only 3. Remember, this is what I used for the beading on the frame and sill before replacing the window. I might have to take those three out and do them again.
I'm also using Dynatron 550 for the caulking on the outside. I like working with it.

Sent from my SM-N910V using Tapatalk

Hello! When you say "beading on the frame", do you mean you put it inside the window frame? Not just the seam on the outside, but all along the inner edge of the window that goes inside the window frame and you dont see anymore?

[Sevier]

Originally Posted by Tango

Get the "good stuff". No need for "adhesive" action but you do want something that stays pliant and bonds well. 3M's urethane sealer is UV resistant and what most auto makers use at the factory. Cheap? No. But it works like gangbusters. I am in the process of running over 110 feet of beads with it on my rig. Wear gloves BTW. Any kind of urethane stuff stains the beejeezus out of your hands .



https://www.3m.com/3M/en_US/company-...3242000&rt=rud

Originally Posted by EastCoastCB

Butly tape and dynatron 550 will seal it up, you just have to be precise and thorough.

Originally Posted by Tango

DOn't use "caulk" or silicone. Get some real Seam Sealer.

Would you all say that Dynotron 550 and 3M Urethane Seam sealer is essentially created equal, could use either/or - regardless of the task? Sealing aluminum window frame to bus wall; sealing glass window pane where it meets aluminum frame; sealing roof seams; inserting rivets wet etc??

[Andre3MC]

Originally Posted by Sevier

Would you all say that Dynotron 550 and 3M Urethane Seam sealer is essentially created equal, could use either/or - regardless of the task? Sealing aluminum window frame to bus wall; sealing glass window pane where it meets aluminum frame; sealing roof seams; inserting rivets wet etc??

I’d like to know what folks think, I’m about to embark on window sealing also.

[Sevier]

Originally Posted by EastCoastCB

Take the windows out, clean all the crappily applied sealant off, apply new seam sealer.
3M Dynatron 550 is what I'd use.

Originally Posted by Drew Bru

Hey all. Our windows are leaking like sieves! It's especially bad in heavy, continuous rain. They've been removed and reinstalled by the previous owner, but it didn't seem to really "take". He used silicone caulk and there was weatherstripping around the perimeter. Not sure exactly where the water is coming in, but I've tried sealing the outside of the windows and at this point I think I'm ready to just pull them, scrape off the old, and reseal them. I did this with one window today and it wasn't too terrible of a job. So, a couple quick questions.

What sealant should I use? From what I've read, my main choices seem to be Butyl Tape (or gutter/butyl caulk?) Thermoplastic Elastometric Sealant or possibly a Polyurethane Window/Siding Sealant.


Do I need weatherstripping? The face of the window-frame mates with the rib-frame of the bus. I'm pretty sure it was a flush-mating sort of fit. The bottom of the window rests on the bus frame.

My gut tells me I should scrape out all of the silicone and weatherstripping (to have clean metal surfaces) and slather a TON of sealant around the perimeter, with a nice heavy bed of sealant for the bottom of the window to set into. I don't care how many tubes of sealant I use, I just don't want to have to do it twice! I don't know if I need weatherstripping or not.

We can't really move forward with our plans until we get this thing water tight.

Thoughts, suggestions, advice? What have you guys done, what has worked for you?

Thanks,
-Drew

Originally Posted by Robin97396

I just used caulk to seal the windows like would be done on any house. Maybe it wasn't right, but my windows haven't leaked at all.

I also threw away the rubber strip at the top of the window. Most weren't in good condition anyway.

Before reinstalling a cleaned window frame I'd put a relatively big bead of caulk on the bus window seat where the window will sit. I push the window into place and secure it as normal, then go outside and caulk the exterior seams where the window frame meets the bus structure. I only used about a tube and a half of caulk after ordering three. I used silkaflex which seemed very soft but is very durable after it cures. I couldn't pull the caulk back off with my fingers so I guess it's pretty tough. I have no idea if what I used was the best or worst, it's just what I used and seems to be good quality. Not endorsing the product, but I am pleased with the result. At the same time I've never caulked bus windows before so I have nothing for comparison.

Hello All -

I recall reading somewhere that Drew discovered the root of their leaky window issue was the gasket. We've removed all our windows, cleaned them and the bus frame, and reinstalled, with pa-lenty of new caulk (urethane, not silicone). Most painful job so far, even more then gutting.

However, after a power-wash on the roof, we noticed there was a bit of water pulling inside the bus, in the little track at the bottom of a few windows. We suspect its the gaskets.

So, how do you all suggest going about sealing up your gaskets? We were going to use Sikaflex 220+, and, well, try to run a bead right over the gasket, to adhere also to the aluminum frame and the glass window. Was going to put painters tape on the glass window to try to keep a nice clean line, so we arent smearing our windows too much and making it look awful. The SkiaFlex can be painted over, and we will be painting our window frames anyway.

And in a few spots where a bit of the gasket has fallen down out of its little gasket crevice, we were going to cut that bit off, and then fill the gasket crive with caulk (will need to cut a teeny tiny hole in the nozzle!)

What do you think?

[Mountain Gnome]

Originally Posted by Sevier

Hello All -

I recall reading somewhere that Drew discovered the root of their leaky window issue was the gasket. We've removed all our windows, cleaned them and the bus frame, and reinstalled, with pa-lenty of new caulk (urethane, not silicone). Most painful job so far, even more then gutting.

However, after a power-wash on the roof, we noticed there was a bit of water pulling inside the bus, in the little track at the bottom of a few windows. We suspect its the gaskets.

So, how do you all suggest going about sealing up your gaskets? We were going to use Sikaflex 220+, and, well, try to run a bead right over the gasket, to adhere also to the aluminum frame and the glass window. Was going to put painters tape on the glass window to try to keep a nice clean line, so we arent smearing our windows too much and making it look awful. The SkiaFlex can be painted over, and we will be painting our window frames anyway.

And in a few spots where a bit of the gasket has fallen down out of its little gasket crevice, we were going to cut that bit off, and then fill the gasket crive with caulk (will need to cut a teeny tiny hole in the nozzle!)

What do you think?

I think you are on the right track.
============


I pulled all the windows out of the entrance side of my bus, except for the most forward one, since the frame of the entrance door overlaps that one window frame about 1×3 inches. I could cut the window frame (cutoff wheel on a Dremel and lots of patience) to get it out, but don't want to do that. I could remove the whole door frame, but that is a real can of worms: the factory sealant around the door frame is still very good, would be a pain to cut-out, clean up, and re-seal, and then there is the whole "take it apart and things don't want to line back up when re-installing" problem to worry about - you just never know how a bit of long term flex or a minor bump that shows no dent can affect the alignment of body parts on vehicles (I love Hondas, for example, but a minor fender bender can cause them to leak water through the roof! - at least the older ones)


The window frames I took out were all scrubbed clean of grime, buffed clean of stains with Bon-Ami (hasn't scratched yet!), polished to a mirror finish, painted with tinted clear-coat (made for polished metals), and re-installed. The clear-coat is holding up well - much better than expected on the aluminum frames - whereas the same paint has flaked off other aluminum/chrome stuff I used it on.


I re-installed those windows with adhesive-tape-backed foam window weather-stripping (not spray foam!) on the sides, and Henry's Crystal Clear sealant (found at HD) on the bottom. I cleaned the bus-frame where the window sits, painted it, then uses painter's tape on that frame and the bottom of the aluminum window frame to create a strait edge, gooped the sealant in the bottom of the window "hole" (bus-frame), and with the foam tape stuck to the window frame, I inserted the window and set it down into the fresh Crystal Clear sealant. Then I used my finger to smooth the sealant bead on the outside, and removed the painter's tape. That seams to have worked well, but I haven't been driving through torrential downpours where wind may try to drive rain past the foam weather stripping on the window sides. But that was 3/4" thick, compressed down to 1/8" or less, so I'm not too worried. If I had used sealant on the sides, removing the windows in the future could be a problem. I had to pry them out as it was, slightly bending one frame, and threatening to crack all the glass, just because of a very little bit of seam-sealer at the top [why it was there, IDK, because the factory window-awning (an extension of the roof panel) fully prevents water from entering there]. As it is now, just the bit of sealant at the bottom will create a chore to remove them in the future if necessary.


I didn't think the one most-forward window was a problem - it didn't seem to leak with a hose. I installed inner wall paneling. It molded. I replaced it with better stuff. It showed water marks and more mold. I finally figured out it was the one window I didn't remove.


So how to re-seal it without removing it?

The outside had dried up sealant around the whole window frame. It looked terrible, and was cracking, and left a large gap under the aluminum frame. It was all hard as a rock, and didn't want to come off easy. I used a steam cleaner to heat it up and soften it. Then it came off real easy like with only an automotive gasket scraper - didn't even need a razor blade until the very end - little bit of residue; I also used a small 90°-angle "pick" to dig the old sealant out from under the aluminum window frame, and in the corners, etc. The bit of condensed water from the steam added just the right amount of lube to keep the softened caulk from sticking to everything else.



Then I ran a bead of Henry's Elastomeric Roofing Sealant around the outside. I think this is what was on there in the first place, and was not factory. This was one of only a few windows that had sealant - some had none at the bottom - only the bit of "glue" at the top mentioned above. I chose this stuff at this time because it remains relatively soft over time. It skins over in a day, but, like, I opened the tube 6 months ago, plugged it with a plastic cap, and all in the tube is still goopy - no need to clean out the nossle-cone or stick a nail into the tube opening to get it to flow again. I used it to seal the A/C coolant lines that come through the roof to the condensers up there, as well as the seam around the custom roof-hatch. Lots of little stuff sticks to it. It shrinks a lot. But it remains soft inside; and so was the 20-year-old caulk around that window that I removed: hard as a rock on the outside, still a bit flexible on the inside. It had "shrunk" so much, it deformed and cracked (bus from Tucson, AZ desert). But I used this stuff, not the Crystal Clear, because it can be removed easier, and some day I hope to get that window out, cleaned, polished, painted, and re-installed properly, like the rest on that side.


The other side of the bus never got the windows done. Too much rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain. Rain..... They didn't leak with a hose, but then as soon as I installed a cabinet on the inside - literally that week - the E-window started leaking when it rained just a little, running down the unfinished (still factory steel) wall to the bracket for the cabinet at the chair-rail, then into the cabinet, to the bottom, where it pooled and began to rust. Gotta love it.


I hit that E-Window frame with the steam cleaner on the outside to clean off the bit of old caulk, and noticed that it made removing the reflective tape that was still on the aluminum window frame real easy - with the same automotive gasket scraper. I couldn't get it off with a razor - at least not without gouging the aluminum. With the steam cleaner, I could scrape it off with a finger-nail. Its glue mostly still remained, though. That was the last of the reflective tape, and the visual difference is amazing considering the little bit that was left. Anyway, I sealed that with the Elastomeric stuff also, since some day when I get to some place where it doesn't rain 3 of 7 days every week for 2 years strait, I'll be taking all the windows out of that side, cleaning, polishing, and painting them, etc. But it takes a full 8-hour day to clean, polish, & prep/tape-off one window, then a week to paint ONE side of a window (paint MUST cure fully on polished metal and be left UNTOUCHED, or forget it!) and another week to paint the other side, and with 9 windows, that is 3-4 weeks of down-time. And it CANT rain while the window paint dries, 'cause there won't be shelter to store them.

[tobeamiss]

I'm real sorrry I'm late on replying.... I've been dealing with "stuff"
But yes, beading the whole inside of the frame before putting the windows back in with Henry's crystal clear.
And then I did exactly what Mountain Nome did on the outside [emoji106]
I'm really late on this so you're probably finished by now. I hope you've made good progress?

[epbecker94]

I’ve been back and forth on if I should even bother resealing the windows in our bus. It’s a slightly newer bus 2010 Chevy 6 window and the way the windows are put in now they have a few different weather strips around it and it all looks solid. To the best of my knowledge they don’t currently leak, (and It’s Florida rainy season right now) but I have not hose tested it yet. My thing is if after the hose test I find zero leaks should I just not mess up a good thing?

I’m afraid that by taking them apart I will be doing more harm than good but then on the other hand I’m wondering how long I have before I do potentially start having problems and my windows start to leak into my fully built bus. Thoughts?

[DeMac]

Originally Posted by epbecker94

I’ve been back and forth on if I should even bother resealing the windows in our bus. It’s a slightly newer bus 2010 Chevy 6 window and the way the windows are put in now they have a few different weather strips around it and it all looks solid. To the best of my knowledge they don’t currently leak, (and It’s Florida rainy season right now) but I have not hose tested it yet. My thing is if after the hose test I find zero leaks should I just not mess up a good thing?

I’m afraid that by taking them apart I will be doing more harm than good but then on the other hand I’m wondering how long I have before I do potentially start having problems and my windows start to leak into my fully built bus. Thoughts?

---------------------------------



You describe fear of the unknown. ie, your confidence in the quality of replacement seals (installed by you) versus the existing seals (factory installed).

Any unskilled person can install a better seal than those installed by the factory. Remove/replace one window & you'll know I'm right.

School bus manufacturers use an inferior rubber & asphalt seal which is designed to be install quickly. Last only 10-12 years

Take your time, remove the old "black-nasty", install a bed of high quality butyl & add closed cell backer rod, if req'd.

Please read this thread for more details:
Skoolie.Net/resealing-windows-on-a-collins-bus

[musigenesis]

I doubt that most bus windows are watertight even straight from the factory. I'm a school bus driver and we got a bunch of brand new IC buses in the fleet over the summer. When it rains, these all have water coming in from the bottoms of the window openings and pooling on the floor. And that's just the visible leaks; more water will be going inside the wall paneling and soaking the plywood underneath the rubber floor.

[epbecker94]

Originally Posted by DeMac

---------------------------------



You describe fear of the unknown. ie, your confidence in the quality of replacement seals (installed by you) versus the existing seals (factory installed).

Any unskilled person can install a better seal than those installed by the factory. Remove/replace one window & you'll know I'm right.

School bus manufacturers use an inferior rubber & asphalt seal which is designed to be install quickly. Last only 10-12 years

Take your time, remove the old "black-nasty", install a bed of high quality butyl & add closed cell backer rod, if req'd.

Please read this thread for more details:
Skoolie.Net/resealing-windows-on-a-collins-bus

Thank you for your very helpful response. I have a couple questions after after reading the thread however. I have butyl tape already which is great but should I use any silicone as well? Or just the butyl tape alone is a good enough seal? With the max air fan install that I’ve done on two builds now I’ve always used the butyl tape and then the silicone.

As for the top of the window I do see the gap that was mentioned there is a seal there as well and then metal are you saying that the pocket in general even if not open to the outside is compromising the insulation? Or is it only if it is open to the outside? Is this where I should put some backing? The picture shows that there is metal behind the gap. I may just be misunderstanding.

[DeMac]

Originally Posted by epbecker94

Thank you for your very helpful response. I have a couple questions after after reading the thread however. I have butyl tape already which is great but should I use any silicone as well? Or just the butyl tape alone is a good enough seal? With the max air fan install that I’ve done on two builds now I’ve always used the butyl tape and then the silicone.

As for the top of the window I do see the gap that was mentioned there is a seal there as well and then metal are you saying that the pocket in general even if not open to the outside is compromising the insulation? Or is it only if it is open to the outside? Is this where I should put some backing? The picture shows that there is metal behind the gap. I may just be misunderstanding.

------------------

Post some photos of your windows.


Your windows & ours may differ, but most factory seals are made of cheap material which has a short half-life.

The grey butyl is a high quality, clay based product, often used in window construction. I do not know of a surface binder or caulking product that would enhance it's quality.

All air pockets & voids ought to be filled. Especially where conduction & convection are likely to occur.


(before adding insulation,
old black factory seal)

(after backer rod,
grey butyl beneath)

Into the void:
above each window, we inserted two feet of 1-1/2" dia, closed cell backer rod.
CCBR is normally used in interior floor expansion joints as an insulated, water-proof barrier for expansion caulk backing.




Note the opening at the top of the frame. When the factory installed window is in place, the space is still visible.


A scrap section of 1-1/2" closed-cell backer rod, demonstrates the size of the void in the steel channel. You can also see the gap, above the adjacent window, just behind the AL frame lip. No water enters due to the overhang. This void is however, a huge source of air convection.

A pocket of dew point, hidden above most school bus windows. Occasional rain? Dew point is every night. More surface area than round of margaritas, no coasters, makes bus a wet napkin.

[epbecker94]

Originally Posted by DeMac

------------------

Post some photos of your windows.


Your windows & ours may differ, but most factory seals are made of cheap material which has a short half-life.

The grey butyl is a high quality, clay based product, often used in window construction. I do not know of a surface binder or caulking product that would enhance it's quality.

All air pockets & voids ought to be filled. Especially where conduction & convection are likely to occur.


(before adding insulation,
old black factory seal)

(after backer rod,
grey butyl beneath)

Into the void:
above each window, we inserted two feet of 1-1/2" dia, closed cell backer rod.
CCBR is normally used in interior floor expansion joints as an insulated, water-proof barrier for expansion caulk backing.




Note the opening at the top of the frame. When the factory installed window is in place, the space is still visible.


A scrap section of 1-1/2" closed-cell backer rod, demonstrates the size of the void in the steel channel. You can also see the gap, above the adjacent window, just behind the AL frame lip. No water enters due to the overhang. This void is however, a huge source of air convection.

A pocket of dew point, hidden above most school bus windows. Occasional rain? Dew point is every night. More surface area than round of margaritas, no coasters, makes bus a wet napkin.

My factory seals seem good that’s why I’ve been hesitant to tear it apart but I also want to go the distance. If I use butyl tape I was just thinking maybe I should use some sort of caulking around the outside crack

Currently there is a gasket that is almost like a rubber weather seal all around the window. I was thinking I should just do something like that again originally.