Originally Posted by Frederick L. Simson
Check out bf_odds_ends
, especially the 5th photograph, which shows a cross-section of a Bigfoot
roof where the vent had been removed. The way I would inspect it is to feel the wrinkled area for softness or squishy-ness. I would ask to remove the vent's trim to see if there's still dampness behind it. If it's dry, then only the thin inner surface needs to be replaced.
Thanks for the pictures, very informative for me too.
From the inside, the Bigfoot
picture looked very similar to mine.
That means water inflitration can cause ROT on the plywood that is under the fiberglass shell
In the case of the Bigfoot fan upgrade, I suspect the small opening has been cut larger to accomodate the new equipment. Someone who has an original Bigfoot may be able to confirm if the foam and plywood core is exposed like that or fiberglassed before the original opening is installed. That would make a big difference. If OEM dome has not been changed (what the picture suggested) there is a chance the foam and plywood core were protected from leaks
. If not, you are talking of potentially wet core and major renovations. This is often the death sentence on sailboats when the deck core gets wet and rots.
Thanks for pointing out the structural and insulation difference between a Bigfoot and my Trillium
4500 which does not have a foam core like that. I don't know for sure if mine has any plywood core on the roof. I found out there is plywood core on the bottom part behind the propane
tank. This leads me to beleive it there is likely some 1/4 plywood core on horizontal sections of my roof, but I don't know for sure.
I will check to see if there are any similar pictures of a cut trough a Trillium
4500 roof. I'm now concerned about Gord's roof damage. Roof damage, Triliium #136
If his roof has such wide cracks, everything is fine if there is no wet plywood under the cracks. Otherwise, there may be more extensive damage and potentially dangerous weak structural points on his roof. Patching a solid fiberglass shell is trivial, performing repairs on a plywood wet core is a far more complex and extensive operation.
Anybody who can tell about structure of a Trillium 1300 or 4500 roof, please let me know (with or without plywood core?).
I'm also surprised by the fact my roof vent appears to be installed differently than the description on the following thread: How to seal roof vents properly
There is no visible edge or any fastener on the bottom of the vent flashing, just a smooth and perfect seal with the Kool Seal I mentionned (performed by previous owner). Considering the effect of direct sun on butyl tape, I prefer it the way it is. Kool Seal produced a permanent, flexible and seamless joint, painted the same color as the shell.