Whether it’s a new build or a home renovation project, doors are always an important feature to how the entrance feels, looks, and works. Get the gate right and you instantly improve ‘curb appeal’ outside as well as the beautifully finished interior.

But there’s more to selecting the right ones than most people think.

As professionals, at Just Wood Furniture we know that with external doors, you need to weigh several factors such as security, severe weather, and protection from termites. What materials are best for your entrance? How different wood types work for outside gates?

And with interior doors, what set of their own spec should you take into consideration. Both, however, have one vital factor to keep in mind – selecting the correct size.

If you are handy with woodwork or simply want to learn then check out these 16000 woodworking plans with easy to follow detailed drawings that include door designs.

This guide looks at standard USA door sizes and the issues associated with XYZ entrance dimensions.

International Residential Code

Few people will know the size of their doors is regulated by the IRC. It is a set of rules to you should follow in the design and construction of residential properties.

The State usually enforces these at a state level and they put rules in place to ensure that buildings comply with health & safety recommendations. Because of this, USA door sizes are fairly standard, at least meeting the minimum dimensions as per the area code.

Standard Exterior USA Door Sizes

Standard dimensions

In the USA, the standard height for an ‘entry door’ is 80 inches tall and 36 inches wide. However, the width can vary from 30, 32, 36 inches as the most prominent, where anything beyond we considere as an exception.

However, because of changes in building regulations, your entrance may not necessarily match these measurements—particularly if your home is more than a few decades old.

The thickness varies between 1 3/4 inches and 2 inches.

The type of material can also affect the dimensions of a door. The height of fiberglass or steel doors, for example, is set at 6 ft 8 inches, and 8 ft.

It is imperative to get a good fit for your front door, as a poorly fitting one may cause security issues as well as letting the weather in!

Ideally, once you measure the door, you discover it is a standard size. If so, replacements are easily available from hardware stores or home improvement centers.

Non-standard dimensions

But don’t be disheartened to discover that your door is ‘non-standard’. Take your measurements along to a local Home Depot or similar, and they will be certain to help you find the right one – though it may cost you a little extra.

Standard Interior USA Door Sizes

For ‘passage’ doors, the standard minimum height is also expected to be 80 inches, with standard widths of 24, 28, 30, 32, and 36 inches.

The standard thickness should be 1 3/8 inches, although it can change to 1 3/4 inches if your door exceeds the 36-inch width standard or 90-inches height standard.

For doors that must allow assisted access, with a minimum width of 36 inches.

Closet doors these days have a height of 96 inches and width of 30 inches, but those in houses built pre-1990 may have very narrow widths – as little as 18 inches.

The IRC, however, stipulates that the minimum size for interior passage doors (any door that allows movement from one room to another) to be at least 80 inches (6 ft 8 ins) and between 28 to 32 inches wide. This doesn’t apply to closet or bathroom doors.

Interestingly, the code does not appear to stipulate the size of bedroom doors, though it may make sense to go with a standard size unless you are happy to incur the extra cost of bespoke units.

Measuring your door correctly

If you’re choosing the replacement door (or doors) yourself, it is best to have precise figures to limit the possibility of buying the wrong size.

Exterior doors

For exterior doors, you may be required to provide measurements four different figures:

  • The door ‘slab’ size—the slab is the actual door itself, apart from any other fittings or frames.
  • The rough opening—this relates to the space between the wall studs to which the door unit will be attached.
  • The masonry opening—this is the measurement from brick to brick on the outside edge of the opening.
  • The unit size— you can calculate this figure by using the rough opening and masonry opening figures, and relates to the frame on which the door slab will be hung.

With regards to the masonry opening, Dean from Render Hero (external rendering specialists) says when starting a new build you must allow up to 22mm extra wall thickness if the rendering has not been applied yet. This can also vary depending on the contractors method of application on the first and second coat so you should consult with them.

You should take measurements from top to bottom and at about three points from side to side.

Confusingly, although there are standard door sizes, this does not mean that all entrances will be standard, and here’s where sidelight combinations come in.

Out swing door sidelight combination assemblies
Out-Swing Door / Sidelight Combination Assemblies

The entrance opening should leave a room of at least 3/4 inches wider and 3/8 inch taller than the door frame.

Interior doors

Measuring your interior doors should be a simpler task than the exterior ones (unless you are replacing the frame as well, in which case you will need to follow the steps for exterior doors) though it still needs to be as accurate as possible.

Assuming that you are replacing only the ‘slab’ itself, then simply record the height, width, and thickness of your existing door. It is a good idea to also note down the dimensions of the frame to compare against your other figures, and to take at least three measurements across the width, from the top, middle and bottom. Not all doors (or frames) are perfectly rectangular, so it might take some minor adjustments to get a perfect fit that will function properly.

If you are replacing double doors, then you must be extra-cautious when measuring! The standard height for these remains at 80 inches, though there is no standard width, the most common ones being 60, 64, and 72 inches.

French doors fall into the same category as ‘passage’ doors, with the standard dimensions of 80 inches by 36 inches—especially so for French doors that lead to the exterior. They will most likely be 1 3/4 inches in thickness.

The process of selecting your new doors need not be a chore—in all probability, your existing units will conform to the standard sizes and replacement will be straightforward. If, however, they are non-standard, all is not lost! Most outlets and suppliers are only too willing to help you find the perfect doors to enhance your home.

What door size do you need?

An upgrade from a single door to double doors can make your home look more sophisticated and elegant. A larger door, even just an increase from 32 to 36 inches, can make your home feel much more open while giving you more room to welcome guests or carry in groceries or new furniture.

An improvement from one door to a double-door entrance will complement the aesthetics and curb appeal of your property. A wider door will also make your home much more accessible from 32 cm to 36 cm and give you more space to welcome guests or bring in heavy luggage, groceries, furnishing, baby strollers, and the list goes on.

If your foyer is small, though, looking into double-doors might not be the best fit, especially if you have a staircase, dressers, or other inventory to make it cramped. Besides functionality and comfort, you have style and good looks. Unfortunately, not every entrance needs a door of a new size.

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