Garrison accuracy:0.55
Garrison damage:0.5
Heavy accuracy:0.5
Heavy damage:0.5
Green cover is slightly better than garrison cover.
Use green cover and shoot from the side with less windows.
Random note I want to pitch in on this. Garrison cover cannot be ignored by closing in. Example of this would be the left house on Khlodney Ferma near the left player's spawn. Even if you're behind that stone wall you'll not get your cover bonus. Same goes to using the yellow cover fences on the building's flanks.
thats why i dont unterstand why they nerf flamer dmg against houses again. if anything, all anti garrison weapons do TOO LITTLE damage
Flamers also tend to hit every model in the house. So if you increase the damage you come closer to what we had not too long ago of flamer 2-3 bursting down entire full health squads in the structure.
As for the PW on buildings if it's instant killing needs to be toned down, but I haven't seen it to truly make a proper judgement.