Effects of agricultural lime dust on metal roof
September 13, 2019
Q. Agricultural lime was recently spread on a neighboring farm and a filmy coating of lime is now on our metal roof, stained porch, and outbuildings. It has rained multiple times and the coating is still there, if not intensified.
Will this lime coating cause short or long-term damage to our metal roof if not removed?
- Mount Cory, Ohio, USA
A. Hi Barb. Lime is quite alkaline -- it's not a neutral powder, so I would imagine it could be harmful to some types of roofs (and gutters if applicable); but many cleaning detergents are quite alkaline as well, so I don't think the effect will be horrendous. You might try to do a google or literature search to see if any relevant papers have been written on the subject because it sounds like it would be reasonably common rather than obscure.
If it's practical to have the roof washed or pressure washed, you probably should.
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Striving to live Aloha