Holes in Fiberglass Roof

Gdetrailer wrote:
Unfortunately, I myself have found that FRP doesn't hold all that well when used for roofing applications.

I used FRP to replace a aluminum roof that the previous owner shot thousands of air nails through as they attempted and failed a rehab of that trailer. The FRP performed well for me for about 7 yrs but after that it started cracking and tearing it's self apart in places with no rhyme or reason..

I don't know the history of this RV except that prior to me purchasing it a year and a half ago, it was set up permanently in this location in central Florida for 7 or 8 years. During the winter the roof is shaded for part of the day by pine trees, but it is in full sun the rest of the year.

When I inspected the roof after purchasing it, I discovered two locations where water had wicked under the FRP and rotted out the plywood, but the color and texture of the entire RFP was uniform then, as it was when I last washed it about three months ago--there wasn't the slightest evidence of any deterioration of the RFP. I'm positive I would have discovered any discoloration or cracks at that time because I cleaned every inch of the roof while on my hands and knees.

Gdetrailer wrote:
For yours, the discolorations look to be rust color to me.

The rust could have come from the substrate layer via staples or other fasteners used to fasten the substrate to the roof framing.

But to get that rust to bleed through it would mean that the cracks developed over time and allowed water to slowly seep into and though the FRP layer..

One of the two soft spots where the plywood has rotted due to water wicking into the FRP's fabric spans a couple of rafters, and yet the color of the surface is uniform--there is no evidence of any rust bleeding through or any cracks despite the RFP having sagged slightly due to lack of support.

I agree, the color of the spots in the picture in my original post certainly looks similar to rust, but the nearest truss is at least a half foot away. And when I look closely at the first picture (I've enlarged part of it below), to me, it does not look like rust that has wicked up through the RFP's, and the cracks seem to imply the consequences of some type of stress.


Click For Full-Size Image.

However, how does that explain the second spot which I discovered because of the discoloration? There are no cracks whatsoever, and as I mentioned, that small area was so soft that when I scratched at it with my fingernail the FRP just disintegrated. However, the same scratching a few inches away only resulted in a barely noticeable indent, and I can not find a similar spot anywhere else. The whole thing remains a mystery to me.

Gdetrailer wrote:
I have found that FRP top layer sheds moisture well, but once the top layer erodes some the moisture can be wicked into and through the FRP and into the substrate under it that it is glued to..

Once the raw fiberglass under the top layer has been exposed to UV from sunlight, it tends to breakdown, gets brittle and flake off.

Discounting these two spots, I can find no evidence the top layer of the FRP is deteriorating and therefor reaching the end of its life. But, the inherent weakness of these types of roofs, namely the constant maintenance, is encouraging me to look closely at roof systems such as Crazy Seal and RV Armor because those products seem to be integrated systems rather than a series of band-aids like that of a typical RV roof.