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Waterproofing the 1/8" thick exposed plywood

RobWNY
Explorer
Explorer
On the inside wall area of the outside kitchen, pass though storage compartment and propane tank areas of my 5th Wheel, there is exposed plywood or paneling type material. The most concerning would be where the propane tanks are mounted because it's open underneath and spray will get in there if traveling when it's raining or there's wet roads. Sooner rather than later it will rot. I'd like to avoid that before it starts. Any ideas what I should do to protect it?

2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.
21 REPLIES 21

MFL
Nomad II
Nomad II
Thermoguy wrote:
RobWNY wrote:
Whether it needed to be done or not, it was an hour job. Being retired, I have a lot of free time.


Good job. I guess if I had a new trailer and had ever even noticed this, I would have found a way to protect it just for piece of mind.


Yup, some of us are a bit more about perfection, than others, wanting things to look, fit, and work just right (me)!

I likely would be fired first day, as an RV builder, on an assembly team!:B

Jerry

Thermoguy
Explorer II
Explorer II
RobWNY wrote:
Whether it needed to be done or not, it was an hour job. Being retired, I have a lot of free time.


Good job. I guess if I had a new trailer and had ever even noticed this, I would have found a way to protect it just for piece of mind.

Thermoguy
Explorer II
Explorer II
Huntindog wrote:
Thermoguy wrote:
I had to remove my propane tank on my 2006 5th Wheel yesterday. Same idea, open to the outside air underneath. I see the exact same setup that you have in your picture. However, after 14 years, it looks exactly the same, no rot, no degradation to the material. Not sure, but it sounds like you are fixing a problem that doesn't exist.
Depends on how often one tows in nasty weather.

I'd wager most here are fair weather campers.

I am not. Just about always I am going somewhere on a specific date for a reason. And we just take whatever mother nature thows at us in stride... In fact when I am hunting I love nasty weather. It sends most everyone else home.
Hunting is great with less people in the woods.

I will look my new Momentum 398 over closely when it arrives.


I live in WA....

Just saying, can't get away from wet weather at some point. And, mine is 14 years old...

RobWNY
Explorer
Explorer
Whether it needed to be done or not, it was an hour job. Being retired, I have a lot of free time.
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.

Retired_JSO
Explorer
Explorer
It will be fine. After several years towing the same fifth wheel, I have to clean the area of dust, spiders, and wasp. Never had any sign of water/spray entering that area.

Huntindog
Explorer
Explorer
Thermoguy wrote:
I had to remove my propane tank on my 2006 5th Wheel yesterday. Same idea, open to the outside air underneath. I see the exact same setup that you have in your picture. However, after 14 years, it looks exactly the same, no rot, no degradation to the material. Not sure, but it sounds like you are fixing a problem that doesn't exist.
Depends on how often one tows in nasty weather.

I'd wager most here are fair weather campers.

I am not. Just about always I am going somewhere on a specific date for a reason. And we just take whatever mother nature thows at us in stride... In fact when I am hunting I love nasty weather. It sends most everyone else home.
Hunting is great with less people in the woods.

I will look my new Momentum 398 over closely when it arrives.
Huntindog
100% boondocking
2021 Grand Design Momentum 398M
2 bathrooms, no waiting
104 gal grey, 104 black,158 fresh
FullBodyPaint, 3,8Kaxles, DiscBrakes
17.5LRH commercial tires
1860watts solar,800 AH Battleborn batterys
2020 Silverado HighCountry CC DA 4X4 DRW

Thermoguy
Explorer II
Explorer II
I had to remove my propane tank on my 2006 5th Wheel yesterday. Same idea, open to the outside air underneath. I see the exact same setup that you have in your picture. However, after 14 years, it looks exactly the same, no rot, no degradation to the material. Not sure, but it sounds like you are fixing a problem that doesn't exist.

RobWNY
Explorer
Explorer
GDS-3950BH wrote:
Crawl Under and take a really good look for exposed bottom edges of the 1/8" Luan that is the substrate behind the filon on the sidewalls, especially in the wheelwells. Our Grand Design Solitude started to delam above the fender skirts. It was the water from the tires hitting a raw edge and wicking up into the plywood like a sponge. Out of warranty so piss off according to GD. $60K POS.

Thanks for the tip on where else to check. I'll do that!
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.

GDS-3950BH
Explorer
Explorer
Crawl Under and take a really good look for exposed bottom edges of the 1/8" Luan that is the substrate behind the filon on the sidewalls, especially in the wheelwells. Our Grand Design Solitude started to delam above the fender skirts. It was the water from the tires hitting a raw edge and wicking up into the plywood like a sponge. Out of warranty so piss off according to GD. $60K POS.

RobWNY
Explorer
Explorer
Jerry, Ain't that the truth! So far on this "brand New" RV that I haven't used yet, I've had to repair seam tape, corner molding, had the ladder replaced because it was damaged when we bought it, a Schwintek motor quit after putting the slide in/out 5 times and the sealing of the exposed wood. I'm sure I'm not done yet. I just haven't discovered the rest of what's not right yet. LOL
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.

MFL
Nomad II
Nomad II
Good to hear, congrats on a job well done.

When mine was new, I worked on it a little, most every day. My neighbors said they thought I bought a NEW one, so I wouldn't have to be fixing things. I replied, it is new, that is why I am working on it! 🙂 Many don't realize, it's not the same as getting a new car or truck.

Jerry

RobWNY
Explorer
Explorer
Flex Seal turned out great! All exposed wood is now sealed.
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.

RobWNY
Explorer
Explorer
Huntindog wrote:
Don't stop at just the edge. fill the gap between the wood and what appears to be metal tubing. This is why I thought a spray on product would work better... Gravity is gonna fight you trying to get it into the crevices


I'm going to squeeze some caulk behind the piece that isn't flush and clamp it until dry. The two pieces are butted up tight to one another so it's just that one small gap. After it's dry, I'll use the Flex Seal.
2020 Silverado 2500HD LT, CC, 4X4 6.6 Duramax
2021 Grand Design Reflection 311BHS

I asked him to do one thing and he didn't do any of them.

Huntindog
Explorer
Explorer
Don't stop at just the edge. fill the gap between the wood and what appears to be metal tubing. This is why I thought a spray on product would work better... Gravity is gonna fight you trying to get it into the crevices
Huntindog
100% boondocking
2021 Grand Design Momentum 398M
2 bathrooms, no waiting
104 gal grey, 104 black,158 fresh
FullBodyPaint, 3,8Kaxles, DiscBrakes
17.5LRH commercial tires
1860watts solar,800 AH Battleborn batterys
2020 Silverado HighCountry CC DA 4X4 DRW