What is the subframe and why does it affect security?

The subframe is the frame, usually steel on security doors, that is fixed into the wall and onto which the frame and the leaf are then mounted. It is what joins the door to the wall.

It affects security because it is where the force is spread when someone tries to break in. If it is badly anchored, with too few fixing lugs or held in any old way, the whole door can give way even if the leaf and the lock are very good.

Signs that something is not right:

• The frame moves slightly when you push the closed door.
• There are cracks in the plaster around the frame.
• The door started rubbing for no obvious reason.

When an old door is replaced with a security door, deciding whether to keep the subframe or fit a new one is one of the most important parts of the quote. We explain it in security doors.