Doors
How to Replace Interior Doors: A Step-by-Step Guide for DIYers
Learn how to replace interior doors with confidence using this straightforward guide for homeowners of all skill levels.
Replacing interior doors is one of the easiest and most effective ways to refresh the style and functionality of your home. Whether you’re upgrading from hollow-core builder-grade doors to solid-core panels or just swapping out outdated styles for something more modern, learning how to replace interior doors can make a big visual impact without breaking the bank. And the best part? It’s a project that many homeowners can tackle with basic tools and a bit of patience.
Need help finding the right doors or materials? Call 866-739-1636 or contact Builders Surplus for expert advice and affordable options to match your project.
What You’ll Need
Before you begin, make sure you have the right tools and supplies:
Tools:
- Measuring tape
- Hammer
- Screwdriver or drill
- Utility knife
- Pry bar
- Level
- Chisel (optional)
- Nail set (if you’re dealing with trim)
- Saw (if cutting to fit)
Materials:
- New interior door
- New hinges and hardware (if not reusing old ones)
- Wood shims
- Wood filler or caulk
- Paint or stain (if unfinished)
Step 1: Measure Your Existing Door
Proper measurements are critical to a smooth replacement. Most standard interior doors are 1⅜ inches thick and come in heights of 80 inches, with widths ranging from 24 to 36 inches.
Measure the following:
- Height and width of the existing door
- Thickness of the door
- Location of hinges and knob bore (if reusing the frame)
If your new door doesn’t come pre-hung or pre-drilled, this information will help you make accurate modifications.
Step 2: Decide Between Slab and Pre-Hung Doors
There are two types of interior doors to choose from:
- Slab Door: A basic door without a frame, hinges, or hardware—ideal if you’re keeping your existing door frame and trim.
- Pre-Hung Door: Comes already attached to a frame—best if you’re replacing a damaged frame or want a clean install.
If your door frame is in good condition and you’re confident in your measurements, a slab door is usually the more budget-friendly option.
Step 3: Remove the Old Door
Removing the old door is simple with the right approach.
- Pop the hinge pins: Use a screwdriver and hammer to tap them out from the bottom.
- Lift the door off the hinges: Carefully pull the door toward you once the pins are removed.
- Unscrew hinges (if replacing): Remove hinges from the frame if you’re installing new ones.
- Remove the old frame (for pre-hung doors): Use a utility knife to score caulk or paint lines, then pry the trim and frame out gently.
Step 4: Fit and Trim the New Door (if needed)
If you’re installing a slab door, you may need to trim it to fit your existing frame.
- Place the old door on top of the new one and trace the outline if the sizes differ.
- Use a circular saw or planer to trim edges as needed.
- Sand any rough areas to ensure a clean fit.
- Use a level to check that your door is straight and square.
Make sure to trim only a little at a time—you can always take off more, but you can’t put it back!
Step 5: Cut for Hinges and Handle (Slab Door Only)
If your door doesn’t come pre-cut, you’ll need to mark and cut for the hinges and handle:
- Hinges: Mark the location based on your old door or frame. Use a chisel to create a shallow mortise so the hinge sits flush.
- Handle: Use a hole saw to drill the knob and latch holes, making sure they align with the frame’s strike plate.
Take your time here—accurate cuts will save you frustration during installation.
Step 6: Attach Hinges and Hang the Door
Once the door is sized and prepped:
- Attach hinges to the door. Use the same number and spacing as the original.
- Place the door into the frame. Use wood shims to support it at the proper height.
- Screw hinges into the frame. Start with the top hinge to check alignment before attaching the rest.
Open and close the door to make sure it swings freely. Adjust as needed with shims or hinge screws.
Step 7: Install the Handle and Latch
Most interior doors use a standard doorknob or lever handle set. Installation typically involves:
- Inserting the latch into the edge of the door
- Aligning and securing the knob or lever
- Ensuring the latch lines up with the strike plate
Double-check the fit and function before finishing up.
Step 8: Touch Up and Finish
Once your new door is installed:
- Fill any gaps or holes with wood filler or caulk
- Sand and touch up trim if needed
- Paint or stain the door (if it’s unfinished)
- Reinstall or replace trim if using a pre-hung door
Take a moment to admire your work—replacing interior doors is a satisfying project that instantly upgrades your home’s interior.
Optional Upgrades to Consider
While you’re updating doors, consider these bonus improvements:
- Add soft-close hinges for a quiet touch
- Upgrade to privacy locks in bathrooms or bedrooms
- Install soundproofing seals for better acoustics
- Choose decorative knobs that match your style
- Replace trim and casing to match modern moulding styles
These small touches can make your new door feel custom and high-end.
Make Your Interior Door Upgrade Easy with Builders Surplus
Learning how to replace interior doors is a smart and approachable project that can dramatically improve the appearance and flow of your home. Whether you’re aiming for a sleek modern look, rustic charm, or classic panel doors, you’ll find that new doors bring an immediate sense of polish and style.
Need help selecting doors, hardware, or trim? Call 866-739-1636 or get in touch with Builders Surplus for guidance, quality materials, and pricing that works for your budget.
Shop Interior Doors at Builders Surplus in New England
Builders Surplus proudly supplies homeowners and contractors in Massachusetts, Rhode Island, and Connecticut with a wide variety of interior doors, trim, and millwork products. From traditional panel doors to sleek modern slabs and everything in between, you’ll find affordable, first-quality options for every room in your home.