How to add damage to all doors

[semak]

Hello everyone..I hope someone can help me with  Indestructible Bases. 

What is our problem and what we could really use help with is that our Doors/Garage can be only destroyed but with one c4.. is there any chance to make or give more armor to them?

lets say 3-4 c4 istead of 1..

Really need help with it its a bit bad when 1 c4 can demolish whole base.


Reallly need your help..