Repairing rotted wood on fiberglass.

[NiCad]

Hey Guys and Gals,

First wanted to thank you everyone in the community here for the help you all have unknowingly given me and a friend thus far in our conversion repair (84' Chevy g20 fiberglass hightop Horizon) 

Sorry If this is not the right spot for this, I didnt exactly see a forum for 1 off questions or tips since I normally just use the search function but was coming up empty on this one.  

Longer story short, during the demo we saw hidden water damage, opened the ceiling and rot and mold everywhere. so the A/C unit needs to come off and have all that wood replaced.  Here are a few pictures so you can see what I mean!



Pretty nasty, right....all that white stuff?  oh yea..mold.  So now that I'm getting into it is that piece of plywood that is direct contact to the fiberglass on the ceiling I believe is glued on.  Glued on using whatever that black stuff is on the sidewall.  My question I have is how do you guys and gals think I can actually separate the wood from the fiberglass then remove the adhesive from the fiberglass without damaging it.  

Thanks again in advance, 

NiCad

 

[user 15722]

First, I would set a circular saw VERY shallow and make a bunch of kerfs across that piece of ply.
(Like pretty close ! 1/4" or 1/2 ")
Then gently use a wood chisel to get what I could off.
After most is gone, I would get an abrasive disk and mini grinder from harbor freight and take it down to the glass.
They make abrasive disks down to like, 36grit or so... you probably don't need that coarse.
After the wood and prior adhesive have been removed, you are good as new for purposes of glassing another piece back up there, if that's what you wish. I must be Very dry to do resin work.
Have fun, you will get the itchies ! wheels

 

[Almost There]

Boy have you got a job ahead of you!

That wood looks liike it is fiberglassed on to the fiberglass roof so about the only way to get it off is to try to get a flat saw blade in between the wood and the fiberglass. I'd try a hacksaw blade minus the holder.

Either that or carefully chip away the rotten wood with anything that will work. Then sandpaper the rough stuff to smooth it out. You're not trying to get it super smooth, just get the rough stuff off so it matches the rest of the fiberglass roof.

The rotten wood is meant to reinforce the fiberglass so you'll want to replace it as you go. Proper way is to fiberglass replacement wood in place but you may want to take a shortcut and glue the wood in place.

It looks like someone screwed things to the wood and used screws that were too long. You will probably need to get above the roof and patch the fiberglass up there too and then repaint it. Then run a water test to make sure you got all the leaks.

I had holes in my fiberglass roof as well when I gutted it. Had to have a total of 15 holes repaired...one I used a wine cork in over the winter to stop the snow coming in!

 

[highdesertranger]

all that wood is actually OSB. I would never use OSB for anything, however RV manufacturers don't feel the same way about OSB as I do. your going to have to do like Almost There said and get that rotten wood out of there. then epoxy new wood in its place. for replacement wood I would use marine plywood as my first choice, real wood as my second choice, exterior grade plywood as my last choice. highdesertranger

 

[NiCad]

Thanks for the advise and sorry for the delay, we've had nothing but rain for almost 2 weeks, really put a damper on my motivation to work outside.  

I ended up convincing myself there'd be no doing this without a new tool (yesssss) went out and picked up an oscillating tool in place of the reciprocating saw and I think what I'm going to try is using Wheels suggestion of making very shallow relief cuts in the OSB then using the oscillating tool to work my way through it slowly. 

Once thats all off I'll end up replacing everything with marine grade plywood, or pine boarding, we'll see what money looks like around then.

I dont even want to get into the screw situation on the roof right now.  The guy we got it from didnt have any vent caps on the brown or grey water vents and it had looked like it was replaced at some point half heartedly.  Heres a couple pictures of that part of it, in the first picture you can see that it wasent even sitting flush with the roof and there is a huge gap between the vent cap and the rib on the roof.  The discolored ring is where the previous owner just gooped on tons of caulking (like the other puddles of it...but far more), and all the work we have ahead of us around that railing at every points it attaches to the fiberglass hightop.

Vent cap before.
Vent cap after

Not 100% sure we'll be getting to the A/C unit this year just because we know its watertight, we're working on the slide out bed over the cab right now and refinishing the front section, we'll see how far we end up getting before the snow starts to fly.

Thanks again for the advise., if I get more updates I'll likely end up changing the name of the thread to something more...conversion/modification storyesque.  But when we start on the A/C i'll definitely post progress pictures of that.

 

[sreesekelley]

Sail Life (youtube channel) just replaced the entire core of his fiberglass deck. ocillating tool is what he used. In fact he used several of them. I vote for marine plywood. If i ever does get wet again the glues will hold up better.

 

[shadow]

I see that you are using clear silicone to seal your new vents. That is not the correct sealer to use, and it will not last.
You need to use a good sealer like Dicor, it is made for rv`s and works quite well.

Dicor is the only sealer I use on my rv.

 

[NiCad]

@sreesekelley thanks for the tip, i'll have to check out the youtube channel, im sure there will be nuggets of info on there that I'll find useful.

@shadow i didnt use your typical silicon to seal it, at least i dont think.  I used the RTV Auto / Marine silicon sealant from DAP.  I twas advertised at least for being staying flexible, not shrinking or cracking and does fine in saltwater and sunlight.  Do you think that stuff would do fine?  I dont mind re-doing it at all if it wont last,  but when I was looking into sealant a few places on the internets had mentioned this so I went with it.

 

[sreesekelley]

@sreesekelley thanks for the tip, i'll have to check out the youtube channel, im sure there will be nuggets of info on there that I'll find useful.

@shadow i didnt use your typical silicon to seal it, at least i dont think.  I used the RTV Auto / Marine silicon sealant from DAP.  I twas advertised at least for being staying flexible, not shrinking or cracking and does fine in saltwater and sunlight.  Do you think that stuff would do fine?  I dont mind re-doing it at all if it wont last,  but when I was looking into sealant a few places on the internets had mentioned this so I went with it.

his channel has been on for awhile.  The deck core replacement has been the last 1/2 dozen episodes.  he is meticulous in his descriptions of what he's doing and why.  he also has a dog that looks like mine which is how I started watching the channel in the first place.