How To Measure Internal Doors

There are some generally accepted conventions for how a property should be laid out, and which way doors should swing. Traditionally, exterior doors open inward. Closet doors will open outward, and interior doors to rooms will open inward. This means a door from a hall to a living room will open into the living room. Where there is not a clear ‘inside’ - for example the door leading from the kitchen to the living room, there is not a hard and fast rule.

In the kitchen/living room example, it would make the most sense for the door to open into the living room. This is because it would offer more space in the kitchen and make it less likely that the door would get in the way, or that someone would be bumped by the door opening while carrying something hot.

It makes sense for doors to ‘secure’ rooms to open inward, because the person on the ‘inner’ side has access to the hinges. It is possible to open a locked door by removing the door from the hinges, so it would not make sense for the hinges to be on the outside.

Following the same logic, some people may opt to have a lock on the guest bedroom door to give the guests privacy, but have the hinges on the opposite side. This means that in an emergency it would be possible to access the room with minimal damage and disruption.

Similar logic can even be applied to shower doors. Having a shower door open inwards may make it difficult to help someone who slips and falls, while if it opens outwards, it is easier to get inside to provide assistance.

There are many different kinds of hinges that can be used to hang doors. The most common one used in modern homes is the butt hinge.

Butt Hinge

Butt hinges are offered in a range of different finishes, and made from different materials - including soft metals such as brass, and ‘hard’ finishes such as stainless steel. Where soft metals are used, there are often stainless steel or phosphor bronze washers fitted between the knuckles to prolong the useful life of the hinge. One of the main concerns with butt hinges however, is corrosion.    

One thing you need to pay attention to when buying new hinges is the weight and size of the door. Most interior doors are fairly light and any pair of hinges will do for a hollow internal door. Particularly heavy hardwood doors may need three hinges. This is also true of doors that are fitted in high-traffic areas.

Some hinges come with rising butts which can be used to raise the door to clear carpet on one side. These are listed as ‘right hand’ or ‘left hand’ depending on which direction the riser works in.

It is recommended that you fit three hinges for a fire door, and use a hard material that is fire resistant and not prone to warping. A one-hour fire door can weigh up to 55kg, and you may need three class eight hinges for that. A fairly average internal door, by contrast, may weigh just 17.5kg, and in that case you should find that three class three hinges will do the job.       

Butt hinges are typically used for internal doors with a limited range of movement. If you want your door to be able to open 180 degrees and clear a projection then you may prefer a projection hinge or a parliament hinge.  With these, the screw holes are lined to the edge of the flap, and when the hinge is fitted, the knuckle will project beyond the edge of the door. This means that when the door swings open, it will ‘project’ out and will be able to clear any architraving or other decorations around the door frame.

With internal doors, the main considerations are the size and shape of the hinge. For rooms where there is a lot of moisture, such as the bathroom, you might also want to consider corrosion resistance.