MiamiCuse wrote:
....
There are only about six rafters that are in that condition, localized to
one area. Most rot are at the end of the rafter where the fascia is
attached. I think by sistering the end I can support whatever weight I need
to support for the fascia.

If I need to get into the attic to double the whole thing I can do it, I
plan on ripping out all the ceilings anyways so it's possible, but is it
necessary to double sister 18' of rafter when the damage is at the last six
inches? It's not impossible it's doable just more work but I thought that's
an overkill.


No, not if it is only minimally structural as this and your other post
indicate. You need _at least_ 2x the length of the bad back onto good
material and certainly not less than 12-18" as simply a practical matter
of having enough material to make a good joint overlap. Certainly more
is better from a structural standpoint, but 18' for a 6" overhang is
certainly overkill.

As others have noted, the key item is to make sure whatever it was that
allowed the water damage to begin with is resolved prior to anything else.

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