Repair of rafter tails

TJC,
Usually the rafter tails are damaged by wood decay fungi. It could be combined with termite damage or possibly termites alone. My suggestions would be similar. Our restoration company has had good results using borates, 100 consolidant and 200 patch in these situations. The 200 system allows for sheathing and trim fasteners to be easily installed. For large voids, loose fitting wood filler pieces below 20% moisture can be dry fit, consolidated, then inserted into these areas which have been filled approx. 75% with patch. This encapsulates the wood and the rafter plane can be maintained by filling the remaining voids with more patch. When cured this can be tooled flush and a touch up coat applied if needed. If only the tail ends (end grain) are damaged, simply consolidate with multiple coats of 100 then apply the 200 over the wet 100. If time doesen't allow for a wet on wet application, the 200 can be applied over cured 100 consolidant. Wood filler pieces can be encapsulated into large end grain voids as well.

Alternately for seriously damaged rafter tail tops, they can be cut back and fit with an oversized dutchmen and fastened in place with rust resistant screws along with epoxy 100 and 200. The excess wood can be planed and sanded back once cured. I suggest milling the sides and tops first then cutting the tails if needed, to a string line. To protect any fresh end grain cuts on the tails, consolidate them as needed. A picture of this technique performed by Marlowe Restorations LLC can be seen in The National Park Service Preservation Briefs 45 on page 9. These rafter tops and tails were heavily damaged by decay fungi to varying depths and lengths, so the dutchmen/laminations were individually sized, dry fit and fastened, removed, then epoxied and screwed in place. We kept as much original fabric as possible.

The 600 system could also be used but because it cures firm, doesn't lend well to tooling or receiving fasteners once cured, I suggest the 200 system for this application and reserve the 600 for other conditions.

If the tails have to be cut back completely from top to bottom, another technique using fiberglass rebar and epoxy can be used. If anyone would like futher discussion of that technique please reply or post.