blueman wrote:
We have some "architectual" wooden gutters, a portion of which is
decaying/rotting from the inside.

Since the decaying run is only about 6 feet long and since replacing
it would be very expensive, I am looking to repair it.

....
2. Scrape away the worst of the rotted wood (I hope that I don't have
to be too aggressive here)
3. Use RotFix (a low viscosity epoxy) to solidfy the remaining wood
including the semi-rotted areas that I don't remove [supposedly
RotFix is pretty tolerant here]
4. Use SculptWood (a wood like epoxy that you shape like putty) to
fill major gouges and holes
5. Coat the entire inside gutter with System3 epoxy
- Not sure what faring I should use if any
- Wondering also whether I should consider embedding a
fiberglass-like layer in the epoxy (if so, what type should I
use)?
....

Missing step is fix the underlying cause of why this particular section
is failing--generally there's a drainage or other problem that
instigated the failure that needs attention else the other repair is
likely to not last.

Don't know that particular brand/product name, but the wood restoration
epoxies I've used recommend not removing anything but absolutely loose
material. Keep as much of the original as possible and inject the
stabilizing product either via drilling small holes or use a syringe to
do so. Only use the solid repair material to replace actual missing
material. Never used fiberglass in these kinds of repairs; when they
became available did use the microballoons on occasion for bulking up
the solid filler to be slightly more economical.

In general, once had a finish surface returned, did not coat it other
than painting as the original surfaces were; for gutters if there is not
another problem such as slope so water is standing, it should not be
susceptible to recurrence.

I've done quite a lot of ante-bellum restoration work in the Lynchburg,
VA, area years ago on that basis that has lasted nearly 30 years so far...

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