Wood framing and condensation

[Roci]

We have been working on our Thomas Saf-T-Liner conversion for a pretty long time and it seems like every time we think she's finally sealed we find another leak, or discover that condensation is building up in the walls. We didn't use a vapor barrier, and we insulated with spray foam in 85% of the bus. Today's problem was in the windows that we're covering.

Are we just screwed?

Is there always going to be water rotting the walls?

Should we just pull everything out and start over and place a vapor barrier?

Are most people's conversions just full of mold in the walls?

We didn't think the windows leaked and then a CA "Atmospheric River" came rolling through and proved us wrong so we pulled out and resealed all the windows so they're mostly good. Now our problem is condensation on the windows we're covering. It collects, pools, and then makes contact with the wood. so now, for the umpteenth time, we are pulling walls off, removing moldy wood, and trying to figure out how to avoid this.
Help!

[TheHubbardBus]

When you speak of the leaks & condensation, are all these problems in the 15% of the bus that isn't spray-foamed? Or is your foam compromised? As for the vapor barrier, are you saying you didn't place a vapor barrier between the inside of the steel shell of the bus and your insulation, or between your interior living space and your insulation? Are you getting condensation on the interior surface of the spray foam? Where are the leaks... behind the spray foam? Are you saying that you used to have all these problems, but then spray-foamed to fix them, but now they're fixed but your windows are now an issue? Please clarify if you can.

[Rucker]

Originally Posted by Roci

We have been working on our Thomas Saf-T-Liner conversion for a pretty long time and it seems like every time we think she's finally sealed we find another leak, or discover that condensation is building up in the walls. We didn't use a vapor barrier, and we insulated with spray foam in 85% of the bus. Today's problem was in the windows that we're covering.

Are we just screwed?

Is there always going to be water rotting the walls?

Should we just pull everything out and start over and place a vapor barrier?

Are most people's conversions just full of mold in the walls?

We didn't think the windows leaked and then a CA "Atmospheric River" came rolling through and proved us wrong so we pulled out and resealed all the windows so they're mostly good. Now our problem is condensation on the windows we're covering. It collects, pools, and then makes contact with the wood. so now, for the umpteenth time, we are pulling walls off, removing moldy wood, and trying to figure out how to avoid this.
Help!

No, you will be able to fix it. Leaks are one thing; condensation is another.

Sounds like you are able to locate and fix leaks okay, even if it seems like an endless process.

For condensation on the blocked windows, you need zero air gap between the glass (and the sash-the part that holds the glass) and whatever you are blocking the glass with.

It may suck, but you'll need to fit your window covering very tightly against the glass so there is no air that can hang in there and hold/release moisture.

Show us some pictures, happy to make further suggestions.

[HamSkoolie]

Properly applied spray foam is a moisture barrier. If it is applied thick enough that the dew point temp will fall within the foam there will be no condensation.
As for the covered windows, you'd be better off removing the windows completely and riveting/sealing steel panels onto the structure and insulating.

[Drew Bru]

We put in an internal gutter system under the windows, out of frustration, when we couldn't stop the leaking windows. We eventually did stop the leaking windows, but the gutter system works great for condensation. I don't have a picture at the moment, so hopefully the description and my sketch helps a little.

The walls protrude a few inches further from the windows and that left a little ledge of foamboard under the window frame. We dished out the top edge of the foamboard in a U-shape gutter. We lined this U-shape gutter with a butyl backed aluminum flashing material that we found at Home Depot. Its similar to this product on Amazon. It came in a 6"x 25' roll. Condensation drips into the gutter, then we mop it up with paper towels (or leave paper towels in there, since its hidden) and wring them out when it gets too bad. The insulated roll-up shades help immensely with both condensation in the winter, and heat in the summer. They're attached to the sill and use a tension rod to set the height. They tuck up above the gutter and sit on top of the wooden window sill so the gutter system stays out of sight.

I don't know if or how this might apply to your build, but hopefully its something you can adapt or get inspired by.


Found a pic on our build blog https://dazzlingbluebus.wordpress.co...-overdue-post/

[TheHubbardBus]

That's a great idea. Thanks for this, Bru!

[nixon186]

I purchased a 2012 saf t liner at the beginning of November. I immediately removed the seats, and plywood floor. I noticed a few areas of rust on the floor. I used phosphoric acid to neutralize it then painted the floor with rustoleum. I immediately noticed most windows were leaking. I got seam sealer from Napa and sealed the vertical sides of all windows. it helped but there were still leaks. then I sealed the bottom of two of the windows. I tested it with a hose and they still leaked. Getting frustrated, I seam sealed the bottom glass where it met the metal frame. there is a gasket there that I could see and it looked good. running out of options I did it anyways. well, it worked. give it a shot. use masking tape and black seam sealer so it looks good. I was dying to start my build and it was making me crazy looking for the leaks.

[Drew Bru]

Originally Posted by nixon186

Getting frustrated, I seam sealed the bottom glass where it met the metal frame. there is a gasket there that I could see and it looked good. running out of options I did it anyways. well, it worked. give it a shot. use masking tape and black seam sealer so it looks good. I was dying to start my build and it was making me crazy looking for the leaks.

That's exactly where our frustrating and hard to track down leaks were at. Once we sealed those gaskets the water infiltration stopped and the gutters became necessary for condensation and were no longer necessary for leaking.

[DeMac]

Originally Posted by Rucker

No, you will be able to fix it. Leaks are one thing; condensation is another.

Sounds like you are able to locate and fix leaks okay, even if it seems like an endless process.

For condensation on the blocked windows, you need zero air gap between the glass (and the sash-the part that holds the glass) and whatever you are blocking the glass with.

It may suck, but you'll need to fit your window covering very tightly against the glass so there is no air that can hang in there and hold/release moisture.

Show us some pictures, happy to make further suggestions.

‐--------------------------

Rucker has addressed an important source of Convection. Convection causes the most condensation. Conduction & radiation are indirect. Leave the fridge or cooler door slightly open. That dew in the crack is caused by convection.





You may have convection over the top of each window frame. That's where we placed 2 feet of 1-1/2" diameter rod, on top of the window between the bus steel and the window aluminum. Use only Closed Cell Backer Rod.


A scrap section of 1-1/2" ccbr, demonstrates the size of the void in the steel channel, above the stock IC windows. In the pic above, you can also see the factory gap, above the adjacent window, just behind the AL frame's lip. No water enters due to the overhang. This is however, a huge source of air convection. Counting each window, we closed a total of 59.5 feet of 1-1/2" wide air gap. All of our condensation ended on that day. Unexpectedly quieter inside, as well.

[Diverdude0075]

I'm getting close to this point in my build. Thanks for posting and the helpful replies y'all!

[Bigmikeclark]

You also need to make sure that you keep the humidity down. If everything is perfectly sealed and insulated, you will still get condensation on the windows if humidity is not in check

[Oldyeller]

Originally Posted by Roci

We have been working on our Thomas Saf-T-Liner conversion for a pretty long time and it seems like every time we think she's finally sealed we find another leak, or discover that condensation is building up in the walls. We didn't use a vapor barrier, and we insulated with spray foam in 85% of the bus. Today's problem was in the windows that we're covering.

Are we just screwed?

Is there always going to be water rotting the walls?

Should we just pull everything out and start over and place a vapor barrier?

Are most people's conversions just full of mold in the walls?

We didn't think the windows leaked and then a CA "Atmospheric River" came rolling through and proved us wrong so we pulled out and resealed all the windows so they're mostly good. Now our problem is condensation on the windows we're covering. It collects, pools, and then makes contact with the wood. so now, for the umpteenth time, we are pulling walls off, removing moldy wood, and trying to figure out how to avoid this.
Help!

When I shortened my bus I had to remove the interior roof panels from the rear of the bus (all this is documented with pictures in my build thread). I noticed the insulation had black areas in it. Given the location of the black areas I assumed water had penetrated through the damaged top rear corners of the bus where shitty drivers had hit things. I'm not positive this was mold but it makes sense that it was.

At that point I figured I'd better open up the interior ceiling and walls. I was most concerned about the side walls because water poured into the bus through the windows and ran down the walls (I have videos of that in my build thread). I expected to find mold throughout the insulation - I didn't. I removed all the insulation and found a lot of the wall insulation was wet to the touch, but no mold like I found at the rear. I don't know why only one area in the entire bus had what might have been mold unless it had to do with the fact that fiberglass insulation is inorganic, nothing for the mold to eat. Perhaps the damage to the top rear corners was significant enough that organic matter had permeated the insulation sufficient to support mold growth - I don't know, that's a wild-assed guess.

I'm thinking that adding a lot of wood to a wet environment would provide something to support mold growth. I'm still trying to decide whether to leave the sheet metal on my walls or to remove it and cover the walls with some kind of wood product but the water issue gives me pause. I also didn't notice any significant rust on the wall sheet metal so that's a positive for keeping the walls covered with the sheet metal. Ah well, I don't have to make that decision for another 4 or 5 months, not going to worry about it.

[rgjarrell]

What about using relatively water proof material near the windows that will breath a little? Waterproof foam (rigid or closed cell spray foam) and water proof "wood" or a waterproof interior wall material. Metal, plastic, tile, mdo (not MDF) board... Fiberglass wrapped pressure treated osb?

Then it doesn't matter that the inside gets a little "wet". Proper ventilation, heat, AC de humidification will dry up small leaks and condensation and the materials that were wet won't deteriorate.

[TheHubbardBus]

Originally Posted by rgjarrell

What about using relatively water proof material near the windows that will breath a little? Waterproof foam (rigid or closed cell spray foam) and water proof "wood" or a waterproof interior wall material. Metal, plastic, tile, mdo (not MDF) board... Fiberglass wrapped pressure treated osb?

Then it doesn't matter that the inside gets a little "wet". Proper ventilation, heat, AC de humidification will dry up small leaks and condensation and the materials that were wet won't deteriorate.

That's our approach. There are going to be some areas that no matter what are going to be prone to condensation (windows and what's around them a prime example). And others where it might happen despite your best efforts. We're using materials and/or coatings that prevent water damage, and construction techniques which allow moisture to dissipate / dry.

[rgjarrell]

In watching Holmes on homes (old reruns and new Mike Holmes stuff). Black stuff on pink insulation is an indicator of air movement and dirt or soot is on the insulation.

It's not necessarily mold if it's black. If it's dry and black then it's likely due to lack of air barrier or vapor barrier. And it's dirty. Fiberglass is meant to trap air which itself is a good insulator. But it's not sealed so if air is moving through it then it's not really trapping air.

[Rucker]

Originally Posted by Bigmikeclark

You also need to make sure that you keep the humidity down. If everything is perfectly sealed and insulated, you will still get condensation on the windows if humidity is not in check

Exactly. For instance, say no to Mr. Buddy as a primary source of heat, and vent your propane stove when cooking.

[Oldyeller]

Originally Posted by Bigmikeclark

You also need to make sure that you keep the humidity down. If everything is perfectly sealed and insulated, you will still get condensation on the windows if humidity is not in check

Interesting thought. You got me thinking about an issue I'm going to have to address before I go out next fall. I think I'll start a new thread about it. Perhaps I'm not the only one with my particular infirmity.

[boondockshawks]

Originally Posted by DeMac

‐--------------------------

Rucker has addressed an important source of Convection. Convection causes the most condensation. Conduction & radiation are indirect. Leave the fridge or cooler door slightly open. That dew in the crack is caused by convection.

Partially quoted post for readability, but look at the factory gap on the window behind!
I like your closed cell foam solution; filing it away for later.

[DeMac]

Originally Posted by boondockshawks

Partially quoted post for readability, but look at the factory gap on the window behind!
I like your closed cell foam solution; filing it away for later.

We invest alot of discussion & planning about Conduction, but not much about Convection.


The inch & a half diameter close cell backer rod, that we added above the window frames, was sourced from
Best Materials
(about $0.54 per foot)

https://www.bestmaterials.com/detail.aspx?ID=17487