Top coat for wooden roof

[DianneB]

I am looking for something to overlay on the wooden roof on my cruiser to provide additional weather protection and rain sealing.

The roof is about 12 feet in length, shallow slope (peaked, not curved), 8 feet wide, and has a 45 degree step up from the pilothouse roof to the roof of the after deck. The roof sheeting is plywood, presently primed and painted. The roof is structurally sound but may experience small movements or flexing at the joints of the step.

There are numerous items mounted on the roof (solar panels, antenna, loudspeaker, etc.) that will have to mount through the roof.



I had originally been thinking of fibreglassing the entire roof but I don't need the strength and would far prefer something much lighter.

Is there any kind of rolled membrane or other material that could be adhered to the roof that would have good UV resistance, provide waterproofing, and also give a nice finished surface?

Someone had suggested gluing canvas over top and finishing with paint (as apparently was done generations ago in the days of wooden boat building).

Any other ideas? Maybe newer technologies with lower maintenance?

Thanks gang!

[bernd1972]

Apply epoxy with one layer of light glass cloth. Without glass reinforcement the epoxy might develop fine cracks and come of or allow water to get under the coating.

[PAR]

Now that it's in primer, your only choice is paint. A 'glass sheath wouldn't have added much weight (ounces) and a light weight 'glass sheathing (2 to 10 ounce fabric) wouldn't have provided any strange at all, just water proofness and abrasion resistance. A typical 6 ounce sheathing on your roof would have used about 6 yards of material and with the weave filled, would have added about 72 ounces total to the roof.

Canvas is an option that likes to rot and absorb/trap moisture. You can employ a couple of products that will tolerate the movement, polyurethane truck bed liner or elastomeric mobile home roof coating. Both of these products will be heavier the a 'glass sheathing, but will provide a water tight, weather resistant, flexible membrane to the cabin roof.

As to nice finish, both of these coatings are thick. Truck bed liner is usually applied at about 30 mils and elastomeric compounds even thicker. This is two to three times the thickness of regular paints. Because of this it's difficult to get a smooth finish. With truck bed liner you're not going to have a high gloss and it will "chalk" up in a few months. On the other hand, you can use the texture to advantage for under foot traction or you can paint over these membranes. Truck bed liner, if sprayed, can be applied very smooth, though it takes special equipment to do so. I'm not sure about elastomeric compounds, but I suspect the same from these coatings as well.