That's a siloxane. Not so permeable to liquid water (rain) but very permeable to water vapor. Pretty old invention, maybe 1930's, but only used on buildings since perhaps the 1970's after problems with GE Silicones. It would probably be too fluid to bridge the large porosity in honed brick.  Maybe they could try something thicker to bridge the cracks and pores, like Silly Putty.  It's made with a siloxane and boric acid, possibly adding the benefit of making the building a no-fly zone for roaches. Maybe the soon-to-be hysterical commission should start researching the availability of brick red and buff natural-cement color Silly Putty? Since they'll custom make caulk if you buy enough, I wonder how many Silly Putty eggs full this guy with the $10 million bonus would have to buy in order to get them to make enough Richard Morris Hunt Brick Red Silly Putty to clad a whole building (or at least the street front of this one).  I suppose the guy who puts in the order ought to get enough to do the gross area, and not exclude windows and doors.

 Could this be tooled to look like a real brick wall Look at the bright side; it's easily toolable, and shouldn't set too fast., or will the mason have to transfer brick images from the Sunday Comic pages?  In don't see how that's really mason's work; I bet the sheetrockers, or maybe the painters, will come up with some way to claim it.  And if it's a non-union job, we're going to have the giant inflatable rat.   I think this rich guy ought to reconsider the whole thing.

 

I guess that I should sign this silliness. Do you have a union card for that?