Wet subfloor in a 2007 Safari FB 25'

[Isuzusweet]

Originally Posted by zayd

Scott & Tony -- are you using Bluewater 20 or 26? I'm getting a quote on 5/8" 4x10 Bluewater 26 (to eliminate the need for a seam). Minimum order is 5 sheets, but I suspect I won't find a shortage of AS owners in the midwest that would take a sheet or two.

I would definately go with 26 with a trailer. With my motorhome, I could get away with 20.
You will find it a lot easier to install with a center seam. I would do a 3/4" half lap joint in the middle, and where sheets meet together.

Cheers
Sidekick Tony

[bradt]

I used Bluewater 26, it is stronger than 20. They had made a proposal to Airstream specifically for that product. I got the 1/2" 4x8 because it was not special order. My 2007 frame has a wide center member that works well for the seam. It is plenty strong enough. And 1/2" has the advantage of being easier to insert into the deformed 5/8" slot in the aluminum extrusion. After it is all in place, insert 1/8" aluminum shims to make up the 5/8" total thickness.
There is another aspect of Coosa board. It is so light weight and easy to work with by your self. Those who are working alone will benefit. You carry it around like foam insulation. And, once you start working with it, you save every little scrap. Could be useful!
The urethane type glue, such as gorilla glue, bonds it really well.

Brad

[zayd]

I got a quote from my local supplier and they can get 4'x9' sheets of 5/8" Coosa Bluewater 26 board for $330 each, which is roughly their 4x8' 3/4" price. The catch: a minimum order of five sheets. I'm going to post in the Classifieds and see if I can find other folks in the midwest that would like a sheet (or all four if they're doing a shell-off floor replacement).

For my repair, I prefer a full-sheet replacement, even if that adds complexity. The physics nerd in me can give several reasons for that.

I'll keep the thread updated with progress and pictures for others to reference. Thanks for the guidance to this point!

[Doug2009FC]

I recommend you spend a few hours reading "Rotten floor due to water leak!" started by Tennisman on 9/6/2009. My personal contribution started in May 2014 on page 25 and the last post was in July 2017. You will find tons of pictures and methods of how others over came this fatal floor flaw. 2007 to 2010 wasn't the best era of Airstream. Nothing that time, hardwork, or lots of money can't fix.

[kathyblake]

And do a major recaulk around the tail lights - that was where we had a lot of leaking in our 2008 27' FB. (Found after all the usual sources were fixed, but before the interior skin was put back on.) If you have carpet under the bed, check where the wiring comes in from below - all the caulking there was completely gone and water was splashing up from the roads.

[Courtenay]

Hello Zayd

I discovered that the metal flange, that supports the lid of the bumper compartment slips in under the “C” channel into which the plywood fits and protrudes about 2” into the interior of the trailer below the plywood floor. This piece sits directly above the cross member of the trailer frame located directly below the rear of the trailer’s exterior wall. It is attached by the bolts that penetrate the “C” channel, plywood, rear compartment flange and the frame cross member. There is no caulking, but I found a strip of foam tape placed between the “C” channel and the rear bumper compartment flange and frame cross member. The foil backed bubble wrap/ insulation also extended to the outside where it was not caulked but covered only by the belly band and this provided a course for water to enter and saturate the floor plywood.
In the photo, the foam tape has been removed and the bubble wrap cut back, 2-1/2” foam insulation installed, rust on frame cleaned up and painted and polyurethane caulking applied to above and below the thin metal flange protruding into trailer from bumper.
To seal out water entering from the exterior I removed the belly band exposing the joint where the bumper flange slips under the “C” channel to the interior. There was no sealant in place. Caulk this area with a high grade polyurethane with good flexibility designed for marine use. I caulked areas where the bumper flange rests on the trailer frame (see photos) and underneath that flange inside the bumper compartment where it sits on the frame cross member. That completed I used a marine grade polyurethane to caulk the seam at the base of the outer skin where it meets the bumper flange, replaced the belly band over a strip of Butyl tape to help seal the mounting screw penetrations then sealed the top edge of the belly band with Acrylic-R seam sealer purchased from the online Airstream store. I then used polyurethane to caulk the seam at the bottom edge of the belly band and an automotive adhesive tape ( two sided) to attach the chrome strip once the band was refastened.

Hope this post helps you and others.

[Freebird73]

I apologize for butting in but I have gutted and rebuilt a 1973. Drilling all those holes to get to the channel and the bolts is a whole lot harder than just taking down that bottom piece of skin. It takes 5 seconds to drill out a rivet and another 5 seconds to install a new one. And if you are very careful all you have to do is line up the holes. It's like a giant jigsaw puzzle. And while the panels are down you can inspect your insulation for rodent damage or and replace it if it's gotten crunchy from leaks.

[zayd]

Doug -- thanks for reminding me of that thread. I read the entire thing when I started this project, but reading it again would be a good refresher given the guidance here.

kathyblake -- I'm adding taillights to my list, thanks. And I did pull up the bedroom carpet and could actually see daylight through that hole! It's on the list as well.

Courtenay, excellent observation on the seams underneath the bumper plate. It seems that conventional wisdom here is to remove the belly band, caulk the skin-to-bumper-plate seam, then reinstall the belly band. But the additional seams you caulked can allow water in just the same. Great recommendation, thank you.

I was hoping to use 4'x9' Coosa board for the rear floor, but the five board minimum order is a killer, so I'll likely cut up a 4'x8' to work. Just waiting for a break in the snow and ice to get out there!

Thank you again.

[Foiled Again]

I was hoping to use 4'x9' Coosa board for the rear floor, but the five board minimum order is a killer, so I'll likely cut up a 4'x8' to work. Just waiting for a break in the snow and ice to get out there!

Thank you again.

Dumb question- 4x9 Coosa? Even on a wide body the floor is only 8 feet wide. The midline is 8' 6". Why order 9' board?

[crispyboy]

I have replaced floors in AS trailers that were older than the one you are working on. It is impossible to replace the subfloor without cutting the it into 3 pieces.
Once the old floor is out you will understand that you have to slide the plywood into the C-channel. Cut the plywood so it breaks on top of the frame and then slide it in place. One tip which will help you before you take out the old plywood is to measure the interior dimensions (wall to wall). You will have to shove, tap, cuss, etc.. to get the side pieces of flooring into place. When you are done fitting the floor in double check the measurements. There is a good chance you will have to tap things around a bit to square it up. Then fasten down the new subfloor.

[zayd]

Originally Posted by Foiled Again

Dumb question- 4x9 Coosa? Even on a wide body the floor is only 8 feet wide. The midline is 8' 6". Why order 9' board?

Since the subfloor runs underneath the C-channel, it's actually wider than 8'.

[zayd]

Originally Posted by crispyboy

I have replaced floors in AS trailers that were older than the one you are working on. It is impossible to replace the subfloor without cutting the it into 3 pieces.
Once the old floor is out you will understand that you have to slide the plywood into the C-channel. Cut the plywood so it breaks on top of the frame and then slide it in place. One tip which will help you before you take out the old plywood is to measure the interior dimensions (wall to wall). You will have to shove, tap, cuss, etc.. to get the side pieces of flooring into place. When you are done fitting the floor in double check the measurements. There is a good chance you will have to tap things around a bit to square it up. Then fasten down the new subfloor.

crispyboy, as far as I've read (I haven't disassembled yet) from other folks here, this was a design change on the later model Airstreams. The rear-most subfloor panel does not slide into the C-channel, but the channel instead sits on top of it. The panels forward of that rear section do fit inside the channel like you describe. Because the rear section is underneath the channel, I should (theoretically) be able to slide it out. From other advice here, it sounds like it will still not be easy to remove/replace that way.

[zayd]

An update:

The subfloor dried out well, so I decided to leave it as is rather than open up the interior walls to change it out. I'll be sealing up the bumper joint in a day or two and hopefully that area will be done.

As I pulled up the remainder of the floor cover to install new flooring, I found a new leak (see attached pics). It's coming from underneath the water pump area and the shower. Moisture readings are at 13-15%, so it is not soaked. There are no obvious leaks at the water pump connections and poking my probes through the vinyl there gave me the same 13-15% readings. The trailer is open to the sky now and we've had some decent rain/snow showers, so it could be fresh from the outside; then again, it could also be old. Is there a common culprit for a leak in this area? I want to start with recommendations here rather than start poking around blindly.

My flooring install is waiting for this new leak to be addressed, so I'm hoping it's not too difficult of a fix. Thanks!

Zayd