Fiberglassing large holes in rv

[roy vannoy]

I have a large hole in my RV where a window was. What type of fiberglass material can I use to fill the hole. Window is 12"x40". I have use resin and cloth in the past for small holes and edging.

[Lora]

Roy, there is a good thread about fiberglassing. You may not need all the details, but it includes closing a couple of large holes in an egg. Good luck.

[roy vannoy]

Lora, are you talking about reading the similar threads down below? I am a little confused as to where info is located.

[Donna D.]

Harry Young and Dave White are the two members who have posted great info about fiberglassing. Sorry I don't have time to search for the threads right now.

[redbarron55]

I filled in where the front window was and all of the now unused cutouts for the appliances in my Scamp 16' unit with pieces cut from the also removed shower stall. This gave me a flat piece I cut the the size of the hole I wanted to fill. I held it up the the hole and traced the cutout on it and carefully trimmed it to fit.
Then I beveled it at about a 10:1 slope on the inside edges and the same on the outside of the hole I wanted to fill.
I then backed up the outside with some thin boards along the cut lines and used heavy aluminum tape to hold it in place while I built up strips of fiberglass fabric and epoxy resin along the scarf.
This is what the outside looks like by the door.

And here is an out of focus picture of the inside.

Soon someone will post to tell you to use polyester resin which will work just fine as well. I used epoxy because I am more used to it and used it on aircraft repairs and construction.
The fiberglass I used was 6.5 oz. I bought off ebay (so was the 2 gallon kit of 1:1 epoxy.) I cut the fabric into 3" wide strips and this was the most irritating part of the process. I used strips of about 3" X 18" and overlayed them over the scarf.
Later I will lightly grind the outside and use filler to smooth the joint.
The flatter you can join the parts the less work you have to do later to smooth out the panel.
Others may offer a better solution, but I had the fiberglass scrap to work with and that is what I used.

[D White]

Originally Posted by redbarron55

I filled in where the front window was and all of the now unused cutouts for the appliances in my Scamp 16' unit with pieces cut from the also removed shower stall. This gave me a flat piece I cut the the size of the hole I wanted to fill. I held it up the the hole and traced the cutout on it and carefully trimmed it to fit.
Then I beveled it at about a 10:1 slope on the inside edges and the same on the outside of the hole I wanted to fill.
I then backed up the outside with some thin boards along the cut lines and used heavy aluminum tape to hold it in place while I built up strips of fiberglass fabric and epoxy resin along the scarf.
This is what the outside looks like by the door.

And here is an out of focus picture of the inside.

Soon someone will post to tell you to use polyester resin which will work just fine as well. I used epoxy because I am more used to it and used it on aircraft repairs and construction.
The fiberglass I used was 6.5 oz. I bought off ebay (so was the 2 gallon kit of 1:1 epoxy.) I cut the fabric into 3" wide strips and this was the most irritating part of the process. I used strips of about 3" X 18" and overlayed them over the scarf.
Later I will lightly grind the outside and use filler to smooth the joint.
The flatter you can join the parts the less work you have to do later to smooth out the panel.
Others may offer a better solution, but I had the fiberglass scrap to work with and that is what I used.

Excellent...done at home and lifelong lasting repair...Fiberglass Dave

[roy vannoy]

Great job Redbarron, I don't have any shower stall material. Can I use FRB the stuff they use in commercial bathrooms? Fiberglass reinforced board.

[redbarron55]

That is what I plan to use. The wall between the shower and the closet by the door I have built up from the FRP panel, a sheel to blue foam insulation and am 1/4" ply sheet.
All bonded together. I did this because fitting the wall in to the curved surface is difficult and I did that with the foam and transferred this shape to the FRP and plywood.
I can't tell you how well this will work since I haven't finished installing this part yet.

[Lora]

Sorry Roy, I usually try to post the link. Here is the one I was talking about.

https://www.google.com/url?q=http://...1QuyTK5x7DLyvA

posts #8 thru #17 show patching large holes.

There is also some discussion about using fiberglass mat and resin to create your own fiberglass patches.

[D White]

Originally Posted by roy vannoy

Great job Redbarron, I don't have any shower stall material. Can I use FRB the stuff they use in commercial bathrooms? Fiberglass reinforced board.

In general, this is a bad idea. Those panels are hybrid plasticized and many times won't adhere depending on the manufacturer...better to make your own on a flat surface covered with wax paper...cheaper too...Fiberglass Dave

[Donna D.]

And Dave White steps into the discussion

[slimmit]

everybody gets out of shape when they start talking fiberglass. Yes a big hole is difficult, Yes FB is messy, but with planning and a little ingenuity, the outcome will be fine. I took out my fridge grill from my boler and with a piece of alure floor tile which is 1ft x 3ft and wax paper and it screwed to the side of the trailer.(small holes can be filled later) I started laying fiberglass mat from the inside bought from the local Canadian Tire. (I looked at the best stuff at $80+ but I'm not putting this in the water). Take your time and don't over manipulate the fiberglass. lay it out, let it dry and repeat as much as necessary.

[redbarron55]

Originally Posted by redbarron55

That is what I plan to use. The wall between the shower and the closet by the door I have built up from the FRP panel, a sheel to blue foam insulation and am 1/4" ply sheet.
All bonded together. I did this because fitting the wall in to the curved surface is difficult and I did that with the foam and transferred this shape to the FRP and plywood.
I can't tell you how well this will work since I haven't finished installing this part yet.

Let me clarify the above. I was thinking for interior of the bathroom I am building, not as a patch panel. The wall I mentioned is for the interior shower/toilet area and NOT structural fiberglass shell.
The fiberglass panels I cut were from the original Scamp interior of the side shower which I was not reusing and was broken over the door.
Dave is correct on the FRP panels. They are not for this use.
You could use this or any other flat thin material to use for make a flat surface to lay mat up on. be sure to use a mold release or waxed paper.
I found it easier to scarf in a piece of the old fiberglass.
Glue and the FRP panels don't work that well together. The first spray on glue I used on the wall bonding did not hold over a few weeks.

[Mike Watters]

I've plugged (or partially plugged) several large holes in the Amerigo I'm redoing.

For small enough holes, I just covered the hole from the outside with duck tape. As long as the hole is small enough that the tape will hold a reasonable level - it's fine. More than one strip overlapping was fine. With larger holes, I covered the hole from the outside with a sheet of something flat. The side that goes against the trailer was covered in saran wrap. The large sheet of whatever then is attached to the trailer (duck tape or screws). I then would paint on resin, shove in fiberglass mat and paint over again with resin. This gets done for a good 2 or 3 layers. I made sure that the mat and resin went well past the borders of the hole.

After this is completely dry, just peel off the duck tape or saran wrap covered flat stuff. This leaves a filled area that is mostly flat with the exterior. The remaining roughness got filled with body putty (several applications with sanding in between). After it's flat, primer and paint.