They are renovating a house just at the end of my street. And they are making the front door – the main door – what your insurance policy will refer to as the final exit/entry door – a double door.
I’ve also visited three or four customers where the main, front door is a double door.
This is pretty much a no-no. Why are double doors acceptable at the back and not as a final exit door? It’s because you can operate all the bolts of your back door when you leave, but you can’t operate all the bolts of your final exit door when you leave. And only when a double door is secured with – as your insurance company will almost certainly mandate – vertically operating mortised bolts at the top and bottom is it secure. And some insurance policies will ask for both halves of the door to have said vertically operating mortised bolts at the top and the bottom. (A morticed bolt is one that isn’t just screwed to the face of the door – which would be flimsy – but is instead set inside the fabric of the door.)
Furthermore, double doors cannot, in my experience, be secured to British Standard BS3621 – something else your insurance policy might mention. Where typical double doors meet there is what is called a rebate (rabbet in North America). Each door edge has a complementary interlocking L-shape where they meet. No lock I know of is certified to work with the adaptor that is necessary to make what otherwise have been a BS3621 lock work in a rebated edge.
So why are the renovators putting a double front door in I wonder. Some of the old houses around here have very large front doorways. Perhaps they thought they could save the expense of one great big door.