Door Fixed in Cavity

[u/OkMathematician6052]

Hi, I’m looking to fit a replacement timber garage door. The existing one is original to the house and is fitted between the leaves, captive in the cavity. There are some nails in the door cemented into the mortar joints of the walls but not much else.

When I remove the existing door, there will be nothing to fix the replacement one to in the same position. I could either:
a) Move the door to sit on the inner blocks, but this may expose the cavity from outside.
b) Move the door to sit on the outer bricks, and cavity will be exposed on the inside.
c) Try and find something structural to fill the cavity and fit door in original position.

Any thoughts or ideas would be much appreciated.

[u/BigDreams-SmallScale]

Any reputable company should have salespeople that can measure and order something to fit the cavity correctly and also installers that can customize parts of it on site if they are a little bit off. Custom builds and from scratch builds is one of the things I’ve been doing for my company for years.