Sounds like it could be scaly leg mites.
If so, brush your roosts and chickens' legs once a month with a mixture of one part kerosene to two parts linseed oil.
It can also be controlled with ivermectin but there is a meat and egg withdrawal period.
Post a picture. @ChickenCanoe is right, you could have Scaly Leg Mites, I recommend putting Vaseline or petroleum jelly on the legs; it suffocates the mites. But beware, I once thought I had Scaly Leg Mites, and was assured I did by someone here, but it ended up that my chicken just had some dirty under the scales.
Welcome to BYC and the coop! There's a lot of great peeps here! Feel free to ask lots of questions. But most of all, make yourself at home. I'm so glad you decided to joined the BYC family. I look forward to seeing you around BYC.