Truthfully, and I'm trying to help you out and not trying to blast on you. Nobody is really going to notice it driving by. People are so nullified by signs that unless it is a real attention getter, it will go unnoticed. Sure the occational dog walker may take a glance while Sparky's trying to do his biz, but unless that particular sign is in front of people with nothing better to do but read a sign, it's just blended in with everything else.
Odds are that people won't pay attention to, or remember something unless it's destinctively different, that's just the way people process things. A goal for anyone looking to advertise their product or service is to leave that lasting impression.
Two ways of thinking here:
1) By the time a home owner or property manager realizes that they need a roof cleaning service provider, do they remember your sign?
OR
2) Does the sign get the attention of someone, and make them question the need of the service you are offering?
In either of these cases, your company is at the top of their list.
Good Luck with it.