Question – fiberglass repair– gap between wood-floor and “wall” of ori

[lenny247]

Hi All,

Been busy restoring a 16ft scamp with rotten wooden floor in front, especially near doorway. I successfully removed rotted wood and replaced with fresh wood. I used metal strapping to connect original shell to the new floor. I formed an L-shape iwth the stapping and used small bolts to connect to shell and woold screws for the floor. The good news is that the shell is solid and the door now hangs proper. However, I have two questions in regards to planned fibre-glass repair.

1. Is it bad to fibre-glass over bolts in the shell that have been used to connecdt to the strapping? I am worried that bolt and/or movement of it will cause the fibre-glass repair to weaken

2. I have gaps between the wood floor and the shell in some areas. Should I fill these gaps in prior to fibre-glass repair or should I simply use the fibre-glass repair to take care of these gaps? If I fill it in, what to use? I was thinking of using that expanding foam stuff, which I could glass-over and under after it dries/ sets?

Any ideas?

thanks

[Kurt & Ann K.]

lenny247,
I would be extremely cautious about expanding foam. The problem is controlling the rate of expansion. Much damage has been done because often it expands so much that it pushes things around. The classic example is when it is used around doors to seal air leaks and the door jamb becomes warped so severely that the door will no longer open at all.
There is a type which is not supposed to expand, but I've not encountered anyone who has any experience using it.
Please keep us posted on your further experiences with your repairs.

Kurt & Ann K.

[KevinDR]

" There is a type which is not supposed to expand, but I've not encountered anyone who has any experience using it."


I made the mistake of using the stuff that doesn't expand. I found it to be somewhat frustrating and useless. Firstly, maybe it's the type that it is, but I found a non-expanding foam which was latex based. When it set, the foam became a sponge for water. I ended up taking it out and using a little bit of urethane based foam and was careful that it did not expand. The Urethane based foam sort of worked like closed cell foam does.


Regards
Kevin.

[lenny247]

thanks for the replies . . .

[John Perry]

I was thinking of using that expanding foam stuff, which I could glass-over and under after it dries/ sets?

Any ideas?

thanks

Hi Lenny,
I used the expanding foam on the door of my trailer day before yesterday. I stiffend the area around the door knob. If you use small amounts and layer it it seems to expand upwards and not out to the sides enough to warp whatever you are working on.
John

[Darwin Maring]

Fiberglass is nothing but glass fibers either woven, random matted or shot from a chop gun.

What makes it strong is the binary cement that it is applied with and that binary cement is either Epoxy or Polyester resin.

Here is the rule about the resins:

1. Epoxy resin will only stick to epoxy resin.

2. Polyester resin will stick to both polyester and epoxy resins. So, if your camper was put together with polyester resin, you will need to use polyester resin when making the repair.

As far as covering up the bolts, well you should make absolutely certain that you would never have a need to put a wrench on it ever again. You could always cut a hole in the fiberglass to allow the bolt to stick through.

You might want to confer with a boat repair shop before you purchase your supplies.

[Andrew Gibbens]

Here is the rule about the resins:

1. Epoxy resin will only stick to epoxy resin.

2. Polyester resin will stick to both polyester and epoxy resins.

Having worked building boats from both epoxy and polyester, I feel this needs correcting.

1. All resins will only stick well to a sanded, dry surface.

2. Epoxy resin sticks best and is strongest - think of it like hardwood compared to polyester's softwood.

3. Using epoxy to fix polyester is a bit unnecessary, but will do no harm. If you use a similar amount of glass when using epoxy, the repair will be stronger than the original shell, which suits most people.

4. Polyester resin (which includes gel coat resin) will not stick well to freshly-cured epoxy. But there is a trick that solves this - a light skim of polyester car body filler (eg, Bondo) sticks well to sanded epoxy and the gel coat sticks well to sanded filler. No-one knows why this works, but it does!

It is perhaps worth adding that all original trailer laminates are made with polyester resin, as far as I have read here.

Andrew

[Mike Watters]

Fiberglassing over bolts:
I wouldn't worry about it moving and weakening the glass you added. After all, worst case is that it's no worse than if you hadn't glassed over the bolt in the first place. My only concern would be if you thought you might ever want access to that bolt again.
Course, when I did similar repairs in my PlayPac - I glassed away over bolts.


Filling gaps:
That one's harder. I wouldn't use expanding foam for the same reasons mentioned above. I can think of two options depending on the exact situation. If the gaps are considerable and you have reasonable access to the gap, I'd use some of the pink foam house insulation. You can cut it to fit then glass over whatever small seam that's left as well as the foam. Think "drywall repair" here.

The alternative (for smaller gaps) might be to stuff the space with dry fiberglass then pour resin into it to solidify it afterwards.

Mike

[Darwin Maring]

Hay Andy, thanks for the tip. I learned the epoxy / poly thing whild building model airplanes and was told that the poly had a wax like coat that the epoxy would not stick to.

Your tip is most usefull and good to know.

DR

[lenny247]

Thanks Everybody - really helps me out!

I will be using epoxy - West Marine brand - I bought it a while back. I'll be sure to sand the FG surfaces that I will be glassing. From my research, the epoxy should bond well to wood, in my case the floor. As for the gaps, they are considerable in some small spots - an inch or so. I like the foam insulation idea - I may try out a small section to see how it works. As for the bolts, I plan to NEVER remove them so access is not an issue. The bolts only serve to fasten the strapping to the shell and ultimately hold the floor and shell together. I hope that my glass repair will be good for the long-haul - my worry is cracks - this area is somewhat stressed by the door. I will also be re-enforcing the door frame as to negate the stress on this section of the trailer by the door.

[Andrew Gibbens]

I.....was told that the poly had a wax like coat that the epoxy would not stick to.

I may be 'going anal' here:

Polyester resin doesn't have a waxy finish, but two alternative explanations are:

- Epoxy resin does have a waxy finish as amines come to the surface during curing - it's called an 'amine blush', which sounds sweet! That's why epoxy must always be sanded thoroughly before anything is applied on top of it.

- Polyester gel coat resin intended for repairing gel coat has wax added to it, without which it won't fully cure. In a repair, applying the gel coat is the last step, so nothing is being applied to it and the wax doesn't matter. If you wanted to repair over a gel coat repair, then thorough sanding is required. None of this applies to original laminate - that gel coat resin did not contain wax as its tackiness provides part of the bond to the laminating resin.

Are you all getting the idea that sanding is your best friend?

Andrew

[Paul and Libby Smith]

I drilled 50 to 60 holes in a small affected area up front thru the flloor of my scamp 5th wheel, than sanded top and bottom,put duct tape on the holes on the bottom, and the gaps,so the gel wouldent leak thru, layed the presoaked glass matting, poured the fiberglass mix, let it dry, ground it even, re-installed some new carpeting seems to have worked well, I also cut a hole in the door and installed a flush mount double action lock, Paul Smith Orlando fl

[LittleJohn]

Originally Posted by Paul and Libby Smith

I drilled 50 to 60 holes in a small affected area up front thru the flloor of my scamp 5th wheel, than sanded top and bottom,put duct tape on the holes on the bottom, and the gaps,so the gel wouldent leak thru, layed the presoaked glass matting, poured the fiberglass mix, let it dry, ground it even, re-installed some new carpeting seems to have worked well, I also cut a hole in the door and installed a flush mount double action lock, Paul Smith Orlando fl

Is it better to use an orbiter sander or a belt sander because I don't want to be too aggressive when sanding.

[SteveCostello]

Originally Posted by Andrew Gibbens

Having worked building boats from both epoxy and polyester, I feel this needs correcting.

1. All resins will only stick well to a sanded, dry surface.

2. Epoxy resin sticks best and is strongest - think of it like hardwood compared to polyester's softwood.

3. Using epoxy to fix polyester is a bit unnecessary, but will do no harm. If you use a similar amount of glass when using epoxy, the repair will be stronger than the original shell, which suits most people.

4. Polyester resin (which includes gel coat resin) will not stick well to freshly-cured epoxy. But there is a trick that solves this - a light skim of polyester car body filler (eg, Bondo) sticks well to sanded epoxy and the gel coat sticks well to sanded filler. No-one knows why this works, but it does!

It is perhaps worth adding that all original trailer laminates are made with polyester resin, as far as I have read here.

Andrew

Thanks for the all the info. This is my first time working with resin, I hope it turns out well.