In Virginia, homeowners in historically protected areas of Alexandria live with a lot of restrictions.
Now they have a new set of rules to clarify what's allowed -- and what isn't.
Some of the old rules were vague -- like the one that said homeowners must use "historically appropriate materials."
When one homeowner said that meant he should be allowed to use synthetic slate, planning officials decided they needed to create a better sense of certainty for members of the Board of Architectural Review.
"They do not want to be the Board of Arbitrary Review," says Al Cox, historic preservation manager for the city of Alexandria.
He helped craft the new rules.
"You can use a modern material on your building if your building post-dates when that material became commercially available," Cox says.
In other words, no synthetic slate will be allowed on any building constructed before the 1980s, when synthetic slate became commercially available.