Interior Door Specs Contractors Ask for Most, and Why They Matte
August 25, 2026
The specs contractors ask about most are thickness, height, width, core type, hinge prep, bore location, and fire rating. Getting these right before ordering prevents costly mistakes and delays. Stock sizing covers most residential jobs. Custom options exist when they don’t.
Most homeowners pick an interior door by how it looks. Contractors pick it by what it needs to do and whether it will fit.
That difference matters. A door with the wrong bore location wastes time. A door that arrives in the right style but wrong thickness creates problems at install. These are not rare situations. They happen when specs are not confirmed early.
This post covers the interior door specs contractors ask about most and why each one matters.
Standard interior doors are 1-3/8 inches thick. That covers most residential jobs.
Most fire-rated doors are supplied at 1-3/4 inches thick. Code does not set the thickness, but the two sizes are not interchangeable in the same frame. The hardware prep, jamb depth, and stop dimensions all change when you move from standard to fire-rated.
If the frame was built for a 1-3/8-inch door and a 1-3/4-inch door shows up, the stop profile may not work. The door may not seal properly either.
Confirm thickness before ordering.
The most common interior door heights are 6/8, 7/0, and 8/0. 6/8 covers most jobs. Confirm which heights your supplier stocks in the style you want, since availability varies more at 7/0 and 8/0.
6/8 is standard in most older homes and many new builds. 8/0 is more common in newer construction with higher ceilings.
Height affects the rough opening size, the jamb length, and the undercut needed for flooring clearance. A door ordered at the wrong height means a reorder or field modification. Field cutting the top of a door is rarely clean and often voids the warranty.
Measure the opening. Confirm height before anything ships.
The most common interior door widths are 1/6, 2/0, 2/4, 2/6, 2/8, and 3/0. Those six cover most residential situations. Sizes like 1/8, 2/2, and 2/10 also exist when an opening calls for them.
2/6 and 2/8 are most common in bedrooms and hallways. 3/0 is typical for primary suites and accessible applications. Bathrooms are usually 2/4 to 2/8. Narrower sizes come up in closets and utility spaces.
A door that is too narrow leaves a gap. A door that is too wide will not fit without modifying the opening. That means extra drywall and trim work. On older homes, openings are often not square and may not match standard sizing. That is when custom sizing becomes the right call.
Hollow core doors are lighter and less expensive. They work well in bedrooms, closets, and spaces where sound control is not a priority.
Solid core doors are heavier and denser. They reduce sound transmission, feel more solid when closing, and hold up better over time. Common uses include home offices, primary bedrooms, and bathrooms.
The core also affects installation. Solid core doors are heavier. That puts more stress on the hardware, so hinge selection matters more.
Custom sizes and solid core options are available. Confirm availability with your supplier before spec’ing them into a project.
Hinge count follows door height. Doors up to about 60 inches use two hinges. A 6/8 or 7/0 door needs three. An 8/0 door needs four. Solid core doors at any height should get the full count, since the extra weight is what causes sagging.
Hinge locations are measured from the top and bottom of the door. They must match the frame prep. If the door is prepped in a different spot than the frame, the hinges will not line up.
On paint-grade doors, filling and redrilling hinge locations shows in the finished product. Confirm whether the door comes prepped and where the hinges are located before install.
The bore is the hole drilled for the lockset or passage hardware. Pre-bored doors save time, but the bore location must match the hardware being used.
Bore diameter and backset must match the hardware spec. Most residential hardware uses a 2-3/8 inch backset, though 2-3/4 inch shows up too. Confirm which one before ordering. A wrong backset means the latch will not line up with the strike plate. The door will not function correctly.
Confirm bore location and hardware backset before ordering.
Fire-rated interior doors are required in certain spots. Common applications include the door between an attached garage and the home’s living space, unit separation doors in duplexes and townhouses, and commercial or mixed-use projects.
For the garage-to-living space door, code gives three options: a solid wood door at least 1-3/8 inches thick, a solid or honeycomb core steel door at least 1-3/8 inches thick, or a 20-minute fire-rated door. Any of the three can be compliant. The door also has to be self-closing.
Fire-rated doors in the residential line are 1-3/4 inches thick and rated at 20 minutes. Available widths are 2/8 and 3/0.
Using a non-rated door where a rated door is required is a code violation. Inspectors catch it. A labeled fire-rated door is part of a rated assembly. The frame and hardware have to be rated too, and the label goes on both the door and the jamb. Swapping the slab alone does not meet code. Rated doors also cannot be field trimmed beyond the manufacturer’s stated limits without voiding the label.
For fire rating requirements in your area, the International Residential Code published by the ICC is a reliable starting point. Always confirm with your local building department, since local amendments apply.
Most interior doors in the primed molded and MDF categories ship pre-primed and ready to paint.
Style options include raised panel, flat panel, and shaker designs. Available heights, sticking styles, and panel counts vary by style.
MDF doors hold paint well and resist warping and seasonal movement better than solid wood. They are not moisture resistant. Edges need to be sealed, and MDF is a poor choice for bathrooms and laundry rooms with real moisture exposure. They are a solid choice for paint-grade work where a clean, consistent finish matters. For a look at how style options break down, the flush door category is a good example of how simple profiles perform in modern interiors.
Ready to see what’s available? Browse our full interior door selection to find the styles, sizes, and specs that fit your next project.
The most common height is 6/8. The most common widths are 2/6 and 2/8. These cover most bedrooms, hallways, and bathrooms in standard residential construction. Closets often use narrower sizes. Primary suites and accessible spaces often call for 3/0.
Solid core is worth it when sound control matters, when the door gets heavy use, or when the space needs more privacy. Home offices, primary bedrooms, and bathrooms are common examples. Closets and low-traffic utility spaces are usually fine with hollow core.
MDF doors are made from medium-density fiberboard throughout. They hold paint well and resist warping. Molded doors have a composite skin over a structural core. Both are paint-grade and ship pre-primed. MDF tends to give a more consistent finish and resists warping better. Neither one is moisture resistant, so seal the edges in wet rooms.
Yes. Pre-bored doors save time, but the bore location must match the hardware backset being used. Confirm the backset on the hardware before install.
Fire-rated doors are typically required between an attached garage and living space, between units in duplexes and townhouses, and in commercial or mixed-use projects. For the garage door, a 1-3/8 inch solid wood or solid core steel door can also satisfy code, and the door has to be self-closing. Requirements vary by local code. If you are not sure, check with the local building department before ordering.
