Hi Gee does and welcome to GoY. I'ver never heard of anyone painting the side of their house with moss slurry and wonder why you want to do, is the brick or stonework in poor shape?

No idea if it would work, but unless you keep the wall damp by spraying it frequently and regularly, it won't survive, and a damp house wall isn't something most of us want... avoiding that is the reason for guttering and downpipes.

Most people wash off any moss that grows on the house!
Doesn't sound like a very good idea really. If you want algae to grow on clay pots you paint them with milk or yogurt but you can hardly do that with a whole house...
But if the wall is sound and dry I reckon the moss in your slurry would just dry up and die. It would probably only stand a chance on a wall under trees and in shade all day.

You clearly love moss so why not keep it to stones in the garden?

I would think as soon as it rained it would wash off as mosses do not have roots at all. also damp conditions will do harm to the brick work and the action you took may make any buildings insurance invalid.

welcome to GoY too :o)

Hmm...I would put it on garden walls, fake ruins, statuary, water features, or boulders, but not on the house wall.