The number of windows can matter. And I think size may affect it. If alot of troops are on one side of the building and a grenade hits them damage is distributed to each member. Therefore its better to get the nade on the side with more windows because the nade will typically damage everyone on the side of the window it hits.
So as Cranial said, trench is also a building with its slots a very near to each other that increase the effect of any grenades and flame effect?
TY. I have another Q. Is it worth it to make Flak 88's? I sometimes build them and I haven't had mine recrewed yet . But against Brits I tend to notice that once they find out you have a Flak 88, 25pdr shells start raining from hell . And when I build then vs Ami, they're like targets for snipers. But this doesn't happen too often. Should I still build them