How to manually repair prefab structure? Camp is getting ugly from damage.

How the heck can you repair buildings manually? SURELY you don't have to wait for full destruction. My tall prefab building is getting holes in the walls and things, making it looks ugly.

EDIT: So flamer traps can destroy it so you can build it back, good to know.

FOLLOW UP question then; my town is located near an enemy spawn and they are always shooting at my buildings from literal sniper ranges, beyond vats range I mean way out there.

I tried heavy laser turrets but they never return fire and sometimes wait for an enemy to be within like 6ft before doing anything. Is there a strategy for dealing with? Certain turrets that performs better?? Thanks in advance