Sub floor repair/replacement

[Kevin Clark]

Repairing water damage in the new to us Monaco. 
 

there’s 2 layers of subfloor - both 5/8” OSB. 

Whywas there a rubber membrane between the layers? Unfortunately in this case, the rubber membrane prevented the subfloor from drying out and trapped moisture inside, leading to further damage. Wondering what the original purpose was and if I need to replace it.

For bottom layer of OSB, there’s a vapor barrier of some sort  did this serve a purpose? Or was it to make the basement area more presentable?

 

[nvrtoofast]

Hey Kevin. I'm not much help for you here but I am curious what you are looking at. Can you throw up any pics?

[jacwjames]

I think the vapor barrier was a half hearted attempt to protect the OSB flooring from the road elements. 

I had to replace a ~4'X6' section of flooring behind the passenger seat.  Here's a post that I did on the project. 

I posted on my repair back in Dec 2021   I didn't have a membrane between the two layers.  I tried to salvage the vapor barrier, used a piece of 3/4" treated plywood for the bottom piece and before I dropped it into place I put a liberal coat of liquid nail adhesive on it, quickly fastened it down and used a roller to press the vapor barrier into the adhisve/plywood.  Seems to have held, last time I checked it was still in pla

[Kevin Clark]

20 minutes ago, jacwjames said:

I think the vapor barrier was a half hearted attempt to protect the OSB flooring from the road elements. 

I had to replace a ~4'X6' section of flooring behind the passenger seat.  Here's a post that I did on the project. 

I posted on my repair back in Dec 2021   I didn't have a membrane between the two layers.  I tried to salvage the vapor barrier, used a piece of 3/4" treated plywood for the bottom piece and before I dropped it into place I put a liberal coat of liquid nail adhesive on it, quickly fastened it down and used a roller to press the vapor barrier into the adhisve/plywood.  Seems to have held, last time I checked it was still in pla

Thanks for sharing that! I actually read through your entire thread last night to give me a bit of an idea of what I might find when I opened my patient up for surgery this afternoon!

[Just Jim]

I think that also serves as sound deadening... memory is foggy, but seem to remember reading something about a sound barrier.  Maybe just sales speak. 

[LakeBob]

I replaced an approximately 3 x 4 ft portion of the floor in my 09 Dynasty.  As you observed, I ran into two layers of OSB with a rubber membrane between them.  This is listed as a sound barrier in the Monaco brochure.  I did not replace the barrier as it also worked as a great moisture barrier, not allowing any trapped water to dissipate.   The lower barrier is similar to a fiberglass tarp material.   I was careful, trying not to cut this and suceeeded in minimal damage. Taped it together before installing 2 layers of 1/2 inch plywood.  

This is the beginning of my exploration into the damage.  

This tool was essential to cut out the subfloor in tight conditions:

 

This is the lower barrier, the ceiling material of the basement bays:

 

I dont have a good picture of the sound barrier, was a heavy rubber type material, maybe 1/8 inch thick. 

New subfloor installed: 

Edited August 30, 2023 by LakeBob
Images

[Kevin Clark]

Did you replace the sound barrier? Or go without it?

[LakeBob]

I did not replace the sound barrier.  It probably does help reduce sound and vibrations when considering the whole floor of the coach, however it also acts as a very good moisture barrier, trapping any water on the upper floor layer.  The OSB on my upper layer was completely disintegrated, and still wet, and the leak had been repaired a couple years ago. 

[Kevin Clark]

That's exactly what I am experiencing too! It has trapped moisture in there.

When you repaired the floor, since you did not replace the sound barrier, did you have any problem in height difference? Even thought it's probably only 1/16"?

[LakeBob]

Yes, matching the existing floor height was a pain.  The thickness of the old OSB was unusual, compared to the plywood I had access to.  I believe it measured right a 1/2”, cant remember exactly. 

Rremoving the tile from the good flooring still removed a bit of the OSB.  I’m installing a waterproof vinyl so my flooring thickness is less than a tile and mortar floor.   I ending up spreading a floor leveling compound on the damaged OSB areas and got everything close.