Exterior fiberglass repair

Once we completed the interior sides of each fracture zone, we checked to see how securely the new fiberglass on just the inside was holding the shell together.  Things looked pretty good, so we removed the plywood braces and addressed the exterior sides.  When Carl was applying the layers of fiberglass, we noticed that the adhesive tape that we had applied to the exterior sides had bulged out.  So our first step was to ensure that no parts of the fresh fiberglass protruded beyond the finished surface.  It had in some places, so we used the grinder and the sander to carefully take those places back down below the desired finished level.
Next, we applied one layer of woven mesh, followed by one or two layers of chopped strand mesh.  Then we sanded the edges once again to take the levels down to a point just below the finished exterior surface.  Bondo body filler went on next and was easily sanded smooth with the orbital sander.  Even the concave curves of the roof line achieved a smooth contour.  I didn't get any photos of these last stages of work, but here are some showing the trailer as we prepared it for winter storage.

Looks all right, eh?

We prepared the trailer for winter storage by cleaning up some of the old butyl caulking from the window frames.

Then we placed them back in the trailer, holding them in place with wood screws and small pieces of plywood in each of the four corners.

Here is the area above the front window, with sanded Bondo finish.

And the area above the rear window.  Those black dots are just Sharpie marker bleeding through the Bondo.

Inside we've put some of the trailer parts, including the doors and the mattress cushions.  No doubt we will be replacing all of that, but we thought we might need the old ones for reference next spring.

With strips of Ensolite hanging down, it's not a very inviting abode.

And here she is inside her winter shelter.

We won't do any more work on this trailer until next spring.  Over the winter we will make lists of jobs to do and appliances to purchase.  Then we will source-out all the parts and components we'll need, and make a budget for all the work.  Carl has a couple of colour schemes in mind.
But it's good to know that this trailer now has structural integrity; the obvious damage to the shell that may have discouraged a lot of potential buyers is no longer an issue for us.

Fiberglass Work

The repair work has gone quite well.  Carl and I watched several videos on YouTube to get ideas about how to proceed.  We assembled all the necessary supplies and tools:

West System epoxy resin and hardener
Woven fiberglass fabric
Chopped strand mesh
Beer cups and popsicle sticks for mixing
Disposable gloves
Cheap paint brushes
Paper towel
Grinder
Random orbital sander
Drill, and bits
Wood screws and finishing washers
Plywood strips
Adhesive tape
And then, down to business!

This is a view of the front side fracture zone.  The weakened fiberglass around the fracture has been ground out, and the hole is fairly large.  The fiberglass edges have been tapered on the inside and the outside.

This is the fracture at the rear window corner.  You can see the tapered edges.  The duct tape is there to keep the new glass and resin from pushing too far to the outside when they are applied.  The pieces of plywood are screwed from the inside, and they keep the two sides in alignment.  Once the new fiberglass on the inside has set, they will be removed.

Here, Carl is applying new glass and resin to the inside surface of the rear window fracture.  You can see the 2x2 and 1x3 that we used to jack up the roof on the damaged side of the trailer.  This was done so that the fiberglass would set with the correct alignment.

A close-up of the chopped strand mesh going on.

And this is what that repair site looked like once the resin had set.

The fracture at the back of the upper cupboard required several pieces of plywood to get the sides aligned properly.  We used red Tyvek-type tape here because we thought it might peel off better than the duct tape once the resin had set.  I don't think it made much difference.

Here is what it looked like from the inside, before applying the new glass and resin.

And this is what it looked like after the interior layers of glass were set, and the plywood bracing was removed.

We're really pleased with how things have gone so far.  We used two kinds of glass -- woven fabric for the first layer, and chopped strand mesh for building up the required thickness.  The epoxy resin was easy to mix and easy to work with, although it did get pretty viscose after only about 4 or 5 minutes.  We went through a lot of paint brushes, plastic cups, popsicle sticks, and disposable gloves.

Next job -- applying glass and resin to the exterior.