So that you don’t waste everyone’s time and get everyone in a tither, why don’t you have your meeting with the priniciple first, find out the scope of work that they would like, the process that you and them are going to need to go through to get approved or if he/she has some preset annual authority. The time frame they would like, areas they want done. Then take some pics and get back to us with the info then. They’re not going to expect you to walk in the door with a price since you don’t have any info. Tell them you’ll get back to them in a week or two with a proposal if it’s worth the time. These type of projects don’t happen overnite.
I seriously doubt the principle is sitting there with 20k burning a hole in their pocket just waiting for someone to come along and clean the exterior of their school. There’s at least a 95% chance the principle not the final decision maker or even who you need to talk to, but it’s a start. Or worse case, the principle has a $500 budget and thinks they can get the whole school done. Most don’t have a clue what this costs. If that happens to be the case, tell them you may be able to get that one wall done for that, but you’ll get back to them after you measure.