Interior door installation cost: prehung, slab and what changes the price

Installing a standard interior door usually costs about $300 to $900 per door in 2026, door and labor together, for a prehung hollow-core or solid-core door going into an existing opening. Labor alone is often $150 to $350 per door. Solid wood doors, double closet doors, pocket doors and old houses with plaster walls and odd sizes cost more. When you do a whole floor at once, the price per door drops, because the setup and trim work are shared.

Lower Merion TwpApr 2026

The numbers

These ranges come from 2026 cost guides and installer surveys. They vary between sources, so think of them as a starting point.

National figures suggest the Northeast runs somewhat above the average. In older houses around Philadelphia and Lancaster, nonstandard openings and plaster walls push more doors to the upper half of these ranges.

We price each door with its casing, hardware and any wall repair on its own line, and give a per-door number when you are doing many.

Prehung or slab

A slab is the door alone. It hangs on your existing frame and hinges. It makes sense when the frame is in good shape and you want to keep old casing, especially in older houses where the trim is worth saving. It takes careful fitting, because old frames are rarely square, and the hinge mortises and lock bore have to match or be filled and recut.

A prehung door comes already hung in a new frame. The old frame and casing come out, the new unit goes in, and new casing goes on. It costs more in material, takes less fitting and fixes frames that are out of square, damaged or the wrong size.

In the Lower Merion house we finished in 2026, the new doors went in with new casing over new oak flooring. Where new floors meet old floors, the door jamb has to be set at the right height for the finished floor, which is one of the details that is easy to miss.

Lower Merion TwpApr 2026

Hollow core or solid core

• Hollow-core doors are light, cheap and fine for closets. They let sound through and feel light when you close them.
• Solid-core doors have a dense composite core. They block more sound, feel heavier and look like wood doors once painted. They are the usual upgrade for bedrooms and bathrooms.
• Solid wood doors are the most expensive and are used where stain-grade wood is wanted or in historic houses.

The labor for a solid-core door is a little more than hollow-core, because it is heavier and needs three good hinges into solid framing.

What raises the price

Casing

New casing around a door is often a third of the cost. A simple flat casing is quick. A built-up casing with a back band, or a head with a cap and frieze, takes longer. If the new casing has to match old trim in the rest of the house, the profile may need to be ordered or milled.

Odd sizes

Older houses often have doors that are not standard heights or widths. Custom-size prehung doors cost more and take longer to arrive. Cutting a standard door down is possible within limits.

Floor changes

New flooring, a thicker tile floor or a new threshold changes where the door sits. The jamb may need to be raised, the door cut down, or both.

Plaster walls

Pulling old casing off plaster can crack it. We score the paint lines, pull carefully and patch where needed. Patching and painting are separate lines.

Changing the opening

Making a door opening wider, moving it or adding a new one means cutting the wall, adding a header in a bearing wall and patching drywall or plaster. That is framing work, not just door hanging.

How a good interior door install goes

1. Remove the old door, frame and casing, protecting the floor.
2. Check the rough opening for plumb and square, and correct it if it is far out.
3. Set the prehung unit with shims behind each hinge and the strike, not just at the corners.
4. Check the gap around the door, about an eighth of an inch on the sides and top, and adjust.
5. Replace one screw in each hinge with a long screw into the framing, so the door does not sag.
6. Install casing with tight miters, glued and pinned.
7. Install the lockset and strike, and adjust so the door latches without pushing.
8. Fill nail holes and caulk the casing to the wall, ready for paint.

A door that is hung right closes softly, latches the first time and stays where you leave it without swinging open or shut.

Lower Merion TwpApr 2026

Closet doors and double doors

Double closet doors need the two doors to meet evenly in the middle and stay aligned. That takes careful shimming and often a ball catch or astragal. In Media we installed double closet doors with a transom panel above, which needs the head to be dead level so the panel reads right.

MediaFeb 2026

Bifold and sliding closet doors are cheaper to install but less durable. Many homeowners replace them with a pair of hinged doors when the budget allows.

Doing a whole house

Replacing every interior door at once is one of the best value upgrades in an older house. Doing them together means:

• One door style and one hardware finish throughout.
• One casing profile, ordered and cut together.
• Less cost per door for setup and travel.
• Painting all at once.

Plan around six to eight doors per day for a crew doing prehung units with simple casing, fewer with built-up trim or old walls.

Doors with other finish work

Doors are often part of a bigger finish carpentry job: new baseboard, window casing, crown and built-ins. Doing them together means the trim matches and the reveals line up. In Broomall, the new double closet doors went in with new casing in the same rooms where we replaced windows and added crown. See our crown molding cost guide.

Contracts in Pennsylvania

Interior door jobs are home improvement work under Pennsylvania's Home Improvement Consumer Protection Act. Contracts over $500 must be in writing, and you have three business days to cancel. Interior door replacement in existing openings does not need a building permit. New openings in bearing walls usually do.

Common problems with new interior doors, and the fix

Most complaints about interior doors come down to a few installation details:

• The door swings open or shut on its own. The frame is not plumb on the hinge side. The fix is resetting the shims, not adding a heavier hinge.
• The door rubs at the top corner. The top hinge has pulled away. A long screw through the hinge into the stud pulls the door back.
• The latch does not catch. The strike is out of line with the latch. Adjusting or moving the strike fixes it.
• The gap is uneven. The frame was set out of square. A good install has an even gap all around.
• The door drags on new flooring. The door was not cut for the finished floor height. It can be trimmed at the bottom.
• Casing joints open up. Miters were not glued. Glued and pinned miters stay closed.

All of these are easier to get right on the day than to fix later, which is why we check every door before we leave.

Questions people ask about interior door cost

How long does it take to install an interior door? One prehung door with new casing takes a carpenter roughly two to three hours. Whole-house jobs move faster per door.

Can I replace just the door and keep the frame? Yes, if the frame is solid and square. You will usually need the door cut to fit and new hinge and lock preparation.

What is the best interior door for a bedroom? A solid-core door for privacy and sound. Hollow-core is fine for closets and laundry rooms.

Do I need new hardware with new doors? Usually yes, because new doors come bored for standard locksets. It is a good time to switch all hardware to one finish.

Is the estimate free? Yes. We count the doors, check the sizes and the floors, and send a written estimate with a price per door.

See our finish carpentry service and the stairs, doors and bathroom trim project in Lower Merion.

Ask us to price your doors