Thread: White Substance on Attic Beams and Roof Decking

I was putting some items in my attic for storage and noticed that there is a white substance on some of the attic beams and roof decking. It isn't located everywhere, just in some spaces. Mainly around the ridge vent above the flue pipe and attic fan. Any ideas? The substance in hard and powders when you touch it. Almost like the spray on ceiling stuff. Any help as to what this is would be greatly appreciated along with how to get rid of it. The house was built in 1964 and I blew in more insulation when we moved in 3 years ago, but either didn't notice this or pay any attention to it at that time. Thanks.

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Originally Posted by Josh Krautmann

I was putting some items in my attic for storage and noticed that there is a white substance on some of the attic beams and roof decking. It isn't located everywhere, just in some spaces. Mainly around the ridge vent above the flue pipe and attic fan. Any ideas? The substance in hard and powders when you touch it. Almost like the spray on ceiling stuff. Any help as to what this is would be greatly appreciated along with how to get rid of it. The house was built in 1964 and I blew in more insulation when we moved in 3 years ago, but either didn't notice this or pay any attention to it at that time. Thanks.

Every reply will most likely be a SWAG.

My suggestion is to scrape some off into a plastic bag and take it to a local analytical lab and let them analyze it. That is really the only way you will know what it is.

It could also be sap/rosin from the wood drying over time, but most of the time it has a yellow to orange tent to it.

scott is right!
could be insecticide powder used for carpenter Ants
could be overspray.
why spray in an attic?
did not see it on the rafter sides, just the bottom side and roof sheathing
look at the exterior trim along the roof edge
look for any type of damage that may have been patched
that would be evidence of past carpenter ant activity and the need to apply powder in the attic area
most important
listen to scott!!

Thanks for the replies. I am going to have it looked at. Nothing appears to be rotten or have holes in it like those made by an insect. If anyone else has had this problem or something similar please let me know.