I was putting up some outdoor hanging lights. I drilled a pilot hole into the underside of an exposed rafter. When I pulled out he drill bit, dark wood dust slowly streamed out of the hole for a few seconds. Looked like the sand dripping in an hourglass.

Is there any way to repair the rafter? What can I do to diagnose the problem further? I tapped on the rafter and it sounded more hollow than the others.

Rafter with drilled hole

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    Did you collect any material? Rotted wood doesn't look sandy, in my experience. This indeed sounds like termite feces. The problem may extend beyond this rafter, so you should do a thorough inspection.
    – isherwood
    Dec 2, 2020 at 13:32
  • It could be carpenter ants . Subterranean termites are much more common than whatever the other termites are. . They would initially have a earth tunnel into the ground ; have you seen one ? They can become established and abandon the tunnel but I think that is unusual. Dec 2, 2020 at 17:10

1 Answer 1


No, the "by the book" way is to remove the beam all the way back to where there is no damage and replace it. I doubt this is termite damage it is likely dry rot from a roof leak. If your roof is NOT leaking then the dry rot will not continue to happen and in fact if the roof was ever redone it could have been leaking before and they just were lazy and decided 1 beam wouldn't be a problem if they even noticed it.

This is not uncommon in roofs.

In your case if the roof is not leaking you can safely ignore it until the roof wears out and needs to be replaced. Then once they tear off all the shingles you can have them remove the boards from that section and then remove and replace the beam once the roof joists are exposed. If it is just this one beam it's still safe since the roof isn't weight bearing (unless you live in an area where it snows heavily) but if you can get inside the attic and look at all the beams that would be good.

  • 2
    Roof leaks don't cause dry rot. They cause plain ol' wet rot. :) Also, the sandy description doesn't sound like common rot to me. It sounds like termite feces.
    – isherwood
    Dec 2, 2020 at 13:30
  • Actually there's no such thing as "dry rot" wood doesn't rot when it's dry. But for some reason people just love the term "dry rot" And if it is indeed insect damage that high up and there is no path for the critters to get there (no touching trees, etc) the house might be riddled with them. Get into the attic and start looking around, stat. If it's termites there will be a lot of damage and the first order of business is getting an exterminator in. (I discovered a termite infestation in my grandfathers house when I was 7 years old fortunately it was caught really early) Dec 3, 2020 at 9:05

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