i think shutters and blast doors are in a very poor state game play wise.
Blast door:
for me when i imagine a blast door i see a big bulky door that’s going to slam down and be extremely resistant.(but they aren’t.)
So for blast door i propose the fallowing change:
1-they take space so no big structure should be allow to be or be build on the same spot.(walls,doors etc…)(maybe shutters…)
2-we should increase their ability to resist acid, explosions.
3-when they are powered down no human can open it with a crowbar and only T3 maybe some T2 can.
4-they should be rare and placed with at-least reinforced walls on the side(normally your walls are tougher than the doors…)
Shutters:
For me shutters are way more smaller than blast door and can be placed or build on top of doors window frame or be placed on free space.
when i imagine them i see the shutter in aliens so basically tougher version of what’s protecting a mall.
so here is the change i am proposing for shutters:
1-i propose we have multiple variant depending on the base material they are made of since they can fill so many different roles.
shutters come in three variants:
1-aluminuim(for privacy shutters mainly.)
2-metal(to face low and medium security threat.)
3-plasteel(to secure CIC for example.)
you don’t want the same type of shutter to be used for privacy than you want for a structure to withstand a storm…
that’s kinda of the rough ideas i have around blast doors and shutters.
feel free to reply and be constructive in your critic or at-least put up some arguments on why my ideas are terrible thanks. 
i got a lot of refactor to do before i propose this as a PR anyway so take your time…