The security door of my newly bought house is open inside, and the one next door is open outside, an

Wrong, do you mean that opening outside doesn't affect the next door? It's just that the developer said it would affect fire protection?

There is no reason to affect the fire protection, and the developer must come up with clear evidence to explain why the external opening affects the fire protection, if he can't take it out, you first change it to the external opening and then say, they can't help it.

In principle, the real estate certificate has nothing to do with the door, and if you are not given a real estate certificate because of this, you can seek a legal solution. I think this is simply the developer's deliberate attempt to scare you, and there is no basis for it.

However, I don't know the specific situation of you there (there are no pictures), so I recommend that you consult a lawyer.

I think this problem is that they are scaring you, first of all, if you don't let the construction start, it will affect the acceptance, and the main body will be changed, I am doing building materials, I know that the anti-theft door is not suitable can be replaced, the owner can change it according to his own preferences, or more assured, they have no reason to stop you, you can choose independently, you don't have to listen to them, your rights, your freedom.

It is best to get the certificate first and then change the door, it is very simple, and it does not affect all the designs in you, as long as you talk to the anti-theft door manufacturer.

It's pretty simple. You tell them that your security door is not burglar-proof. If it's stolen you don't care ... The state simply does not have a standard for fire prevention and theft prevention.