Why Do Some Doors Have Two Hinges At The Top

I do not recall ever being told why the lower hinge has a higher offset.

Why do some doors have two hinges at the top.

2 hinges can definitely be totally sufficient even for the heaviest of doors. But the conditions of all materials involved may make that untrue. Those are not the measurements that i follow as trade practice but near enough. I once built 4 screen doors for a client out of 3 4 softwood using two hinges.

This depends on quite a few factors probably most importantly being the strength of the wood of your frame and your door and how worn out the current holes are. I was back at the house within a month due to the door stiles bowing. Doors with a security function need to have at least 3 hinges as this makes them more difficult to force. I ended up rebuilding the doors entirely out of 4 4 poplar and hung them with three hinges.

This keeps the top of the door from rubbing on the frame opposite the hinge. From what i understand it is best to have one hinge near the bottom and two hinges near the top of the door to take the weight rather than three hinges equally spaced. I have had 12 years of replacing doors that have been made of everything from solid oak to the new throw away paper mush love that phrase construction superintendent solid wood doors with two good hinges seem to fair better than the mush with cheap hinges. The doors are fire doors these are very heavy and since most of the weight is at the top of the door the two hinges are set near the top the hinge at the bottom of the door does not take as much.

3 hinge doors ditto what jim said. I have always wondered why hospital internal doors that have 3 hinges have the middle hinge positioned so near the top hinge rather than mid way between top bottom hinges. In my dismantling and repair of old houses the common door type was a ledged and brace. The top hinge is a little closer to the top usually about 7 as it is always in tension with the forces applied.

The lower hinge is usually about 10 from the bottom and it is always in compression with the forces applied to it.