FRP Roof Covering

[Chad Fabry]

We added on to our old farmy Italianate house. 

It's mostly done now - I still need to add a few layers of trim and some corbels. The original house has a Medina sandstone foundation I built the addition foundation of the same material. 

The elevations of the addition ended up pretty close to two existing second-story windows that I didn't want to move. It left very little possibility for slope on the roof. So we built a hip roof with the lowest slope being about 1-1/2:12, and the steeper side slopes are about 2-1/2:12.

There's not enough slope for any regular roofing except for products used on flat roofs. 

After a bit of research, I found that it's really common to use FRP(fiberglass reinforced polyester), AKA fiberglass in the UK, so I gave it a shot. 

Most of you know I come from an automotive background, and I'm experienced with fiberglass resins and fiberglass mats/ cloth. Still, there was a lot to learn. I learned a lot about the different resins, cloths, and appropriate weights. It was a fun diversion from peel-and-stick or modbit. 

The roof is two layers of 1708 cloth installed with polyester resin. It's about 220 ft. I used 14 gallons of resin. 

I pre-made the flashings and installed them first with fiberglass cloth and resin. Learning how much resin you can put down at a time was the most anxiety-ridden portion of the project. 

Once the resin and cloth were installed, I protected the assembly with two coats of gel coat—the top coat contains what's referred to as wax. The wax is a mixture of styrene and paraffin wax dissolved in acetone. You mix that into the top coat of gelcoat, and the styrene and paraffin rise to the top during the cure. They create an airproof layer that allows the gel coat to fully harden rather than remain slightly tacky.

I'm fully aware of the pedantic nature of this crowd. The siding is all different colors because I had enough scraps from other jobs to fill it in.

 

 

[Bill Kibbel]

Looks like something that will protect the structure for a very long time.  I gotta ask though, why not terne?  I'm sure you thought about it.  It would have been fun to do standing seams with hips.

[Chad Fabry]

I did soldered seam terne on my balcony. It was *very* time-consuming. 

I considered standing seam metal, but what you can't see in the photos is a flare at the bottom of the slopes. I thought it would look cool, and it does, but you can't see it from the ground. If you visit, be sure to check out the cool flare from the upstairs bathroom window.

I was afraid the standing seam would not accommodate the change of slope. 

[Jim Katen]

And the gel coat is stable in UV light? 

[Chad Fabry]

Quote

And the gel coat is stable in UV light? 

That's what they tell me. Boats and Corvettes seem to fair OK.

It's recoatable, but not really easy to recoat. It requires thorough sanding followed by cleaning with acetone. (I already recoated it once becaue it was the wrong color)

I figured the worst thing that can happen is it fails miserably. If that's the case, it'll make an excellent substrate for something else. 

[Tom Raymond]

That's beautiful.