odd, ive never had this problem. i play on ultra, and only a few times have i ever had a building too small to fit my men in. and then that makes sense. i usually dont garrison buildings however. if you think about it, yah, it gives you some cover, but, honestly, you can only have like 10 men max firing at once. plus a well-aimed cannonball will annhilate most of your unit. trust me. one time i had a single unit of line infantry facing off against 5 units of native irregulars in a building, and killed almost no one. i tried again with them taking cover behind a wall in single line formation instead, and i still lost inevitably, but i killed many more men. unless you have less than 40 men in a unit, dont bother garrisoning any buildings. its pretty useless, plus melee infantry and cannons will destroy you.