M109 rotted floor

[Dixon77]

So, construction has begun
Well, destruction has begun.
I knew the front floor corners were rusted out when I bought my truck, no biggie.
I started removing the wood planks and found the steel subfloor is pretty much gone.
If you've run into this or redone your floors, what did you do?
Did you replace the metal or do marine grade plywood?

Thanks!

 

[Mullaney]

So, construction has begun
Well, destruction has begun.
I knew the front floor corners were rusted out when I bought my truck, no biggie.
I started removing the wood planks and found the steel subfloor is pretty much gone.
If you've run into this or redone your floors, what did you do?
Did you replace the metal or do marine grade plywood?

Thanks!

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Everybody has an opinion, but wood is that it was built with. I would go back with marine grade plywood and paint it on both sides before you start attaching it to the truck bed. Is that steel that you are referring to "sheetmetal" (thin stuff, non structural)?

Might be worth posting up a few pictures to get a better idea of what you are seeing...

 

[Dixon77]

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Everybody has an opinion, but wood is that it was built with. I would go back with marine grade plywood and paint it on both sides before you start attaching it to the truck bed. Is that steel that you are referring to "sheetmetal" (thin stuff, non structural)?

Might be worth posting up a few pictures to get a better idea of what you are seeing...

Yeah, just that 12ish gauge sheet metal. I didn't get any pics while I was in there today since it's a calamity of a shit show. I'm assuming it is just a shell/weather barrier but I didn't know how necessary it is.
The last camper I built I just used marine ply covered with Raptor Liner.

 

[Mullaney]

Yeah, just that 12ish gauge sheet metal. I didn't get any pics while I was in there today since it's a calamity of a shit show. I'm assuming it is just a shell/weather barrier but I didn't know how necessary it is.
The last camper I built I just used marine ply covered with Raptor Liner.

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I think you would be well served with CDX or Marine Grade plywood and lots of paint of some sort of Raptor liner.

 

[Dixon77]

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I think you would be well served with CDX or Marine Grade plywood and lots of paint of some sort of Raptor liner.

So you don't think the steel is worth replacing

 

[cbrTodd]

Did you replace the metal or do marine grade plywood?

Thanks!

I did both. Seemed to me like the metal was there for a reason - to keep the wood from getting wet every time the truck got driven in the rain. I spot welded in a 14 ga sheet similar to how the original was held in, then replaced the oak I took out with two layers of marine grade plywood to roughly match the original wood thickness.

The best advice I can give is to figure out where the water got in to rust and rot it in the first place before you finalize the floor. In my case, there were a couple holes in the roof that I had to patch. And re-patch several years later when the original sealant failed.

 

[Dixon77]

Alright, pics.....
It's a hot mess since I'm still in the demo phase. The substructure and support beams are rock solid but the sheet metal is toast.
I'm still on the fence of replacing the sheet metal or doing a membrane coated 3/4" marine ply with a Raptor coating. This isn't going fording or heavy use like it was designed for anymore. It's going to be a glorified butch Winnebago.

 

[Mullaney]

Alright, pics.....
It's a hot mess since I'm still in the demo phase. The substructure and support beams are rock solid but the sheet metal is toast.
I'm still on the fence of replacing the sheet metal or doing a membrane coated 3/4" marine ply with a Raptor coating. This isn't going fording or heavy use like it was designed for anymore. It's going to be a glorified butch Winnebago.

.
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Looks like an overhead leak of some sort for who knows how many years...

Now you need a rain storm and see where the water is/was coming in. Or maybe a water hose and time. Could be that is only happens going down the road at 40 and the rain blows up and under the outside layer of the outside skin. Again for how many years.

Definitely have to fix the leaks above before repairing what is going on in the floor. I would almost be willing to guarantee that all the fording in the world wouldn't cause what you have happening today.

 

[Dixon77]

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Looks like an overhead leak of some sort for who knows how many years...

Now you need a rain storm and see where the water is/was coming in. Or maybe a water hose and time. Could be that is only happens going down the road at 40 and the rain blows up and under the outside layer of the outside skin. Again for how many years.

Definitely have to fix the leaks above before repairing what is going on in the floor. I would almost be willing to guarantee that all the fording in the world wouldn't cause what you have happening today.

I'm thinking it's splash up from the road and mudd caked in there. I power washed the piss out of it and have been daily driving it the past few weeks thru storms and generally horrific rains. No leaks.
It's all getting gutted regardless. The subfloor replacement materials and sealing up the floor are the first priorities to deal with

 

[TomTime]

Look into the marine, West System Epoxy, to coat you plywood before putting it in. Coat both sides and all edges and it will seal the wood!
I used it on my 34 foot wooden cabin cruiser and other wood project and it worked great…a little expensive but it will protect your wood products.

 

[Rhino 5/4]

Look into the marine, West System Epoxy, to coat you plywood before putting it in. Coat both sides and all edges and it will seal the wood!
I used it on my 34 foot wooden cabin cruiser and other wood project and it worked great…a little expensive but it will protect your wood products.

I haven't started demo on my 109 yet but from what I can tell looking up while working on the brake system I have the same issue as the OP . Hopefully starting soon on tearout. I'll be watching.

 

[chucky]

If yall want to replace the wood your tearing out and go back with new wood please look into ADVANTECH decking ! Its made of woodpecker lips and mother inlaw kisses ! Impervious to the elements they tested it in submerged ocean salt water for years

 

[chucky]

I used it in my bathroom/shower floor and toilet pedestal

 

[ToddJK]

If you just plan on to use wood, I would still consider using some sheets of steel over the tires. The tires will throw dirt at it acting like a sand blaster which could speed up the rot process in any wood. Could even do the whole thing if you found some steel or even aluminum cheap enough from a local scrap yard. The extra money and time will be worth it in the long run if driven often and to keep the maintenance to a minimum. Bad enough, the trucks design and age will provide more than enough maintenance in the years to come. Just my

 

[Dixon77]

If you just plan on to use wood, I would still consider using some sheets of steel over the tires. The tires will throw dirt at it acting like a sand blaster which could speed up the rot process in any wood. Could even do the whole thing if you found some steel or even aluminum cheap enough from a local scrap yard. The extra money and time will be worth it in the long run if driven often and to keep the maintenance to a minimum. Bad enough, the trucks design and age will provide more than enough maintenance in the years to come. Just my

The wheel well plates are rock solid and don't need replaced. Hell, I don't even think I need to pull them.

 

[ToddJK]

The wheel well plates are rock solid and don't need replaced. Hell, I don't even think I need to pull them.

That's a good thing! Honestly, I didn't even know there were separate wheel well plates. Learn something new all the time! Lol

 

[SCSG-G4]

You need to find an old thread by mdmorgan when they re-did the interior of a 109 to make a camper. Complete with foam insulation in the ceiling/walls and taking the driveline out of the rear pumpkin so they would have a larger water tank.

 

[Dixon77]

After a week of on again/off again work, the rotted sections are gone. I found some drilled holes in the front/sides/rear that were open from previous outside bolt ones that were letting water in. I ran bolts with rubber sealing washers and RTV thru and sealed them up.
Now to rust convert, add a seal coat, and do some sub floor.

 

[Dixon77]

On a separate note:
Are these inverter boxes worth anything?

 

[coachgeo]

Look into the marine, West System Epoxy, to coat you plywood before putting it in. Coat both sides and all edges and it will seal the wood!
I used it on my 34 foot wooden cabin cruiser and other wood project and it worked great…a little expensive but it will protect your wood products.

I thought you had to leave something open somewhere one the wood. They breath was the point. If the natural moisture in the wood cant breath out... it will rot itself from the inside out. No personal experience..... just reading to educmacate myself in advance. Curious your input on this.