Install Interior Doors and Hardware
Interior doors define spaces, provide privacy, and add architectural character to your addition. Matching existing door styles and hardware finishes creates visual continuity between old and new spaces.
Quick Summary
Time per door
1-2 hours
Door cost
$50-$500 each
Installation
$75-$200/door
Why This Step Matters
Doors are functional necessities and design elements. A mismatched door style immediately signals "addition" rather than "original home." Properly hung doors with quality hardware feel solid and operate smoothly for decades.
Common Mistake
Using hollow core doors in bathrooms or bedrooms where sound privacy matters. Hollow core doors provide minimal sound blocking—you can hear conversations clearly through them. Solid core costs more but provides real privacy.
Hollow Core vs. Solid Core Doors
Hollow Core
Cost
$50-$120
Weight
15-25 lbs
Sound blocking
STC 20-25 (minimal)
Cardboard honeycomb core with thin veneer faces. Lightweight and affordable but sounds hollow when knocked, provides little privacy, and dents easily. Best for closets.
Solid Core
RecommendedCost
$150-$400
Weight
50-80 lbs
Sound blocking
STC 30-35 (good)
Particleboard or wood fiber core with veneer faces. Feels substantial, provides meaningful sound privacy, and resists damage. Standard for bedrooms and bathrooms.
Real wood solid doors ($300-$500+) are available but rarely necessary for interior use. They're heavier, require more robust hinges, and expand/contract with humidity. Solid core is the practical choice.
Matching Your Existing Door Style
Identify Your Door Style
Common interior door styles include:
- • 6-panel: Traditional, most common in pre-1990s homes
- • 2-panel: Craftsman style, early 1900s to present
- • Flat/flush: Modern, contemporary homes
- • Shaker: Simple raised panel, versatile style
- • Colonial: Multiple raised panels, traditional
Measure Existing Doors
Standard sizes are 80" tall by 24", 28", 30", 32", or 36" wide. Older homes may have non-standard sizes. Measure the door slab itself, not the frame opening.
Watch for: Older homes sometimes have 78" or 84" doors. If your existing doors are non-standard, you'll need special-order doors or frame modifications.
Source Matching Doors
Common panel styles are readily available at home centers. Take a photo of your existing door to compare. If your style is discontinued, millwork shops can create custom doors ($400-$800 each).
Matching Door Hardware
Hardware finish should match throughout connected spaces. Mixing finishes looks haphazard. Common finishes include:
| Finish | Style | Maintenance |
|---|---|---|
| Satin Nickel | Versatile, contemporary to traditional | Low - hides fingerprints |
| Oil-Rubbed Bronze | Traditional, craftsman | Low - patinas naturally |
| Polished Chrome | Modern, contemporary | High - shows fingerprints |
| Matte Black | Modern, industrial, farmhouse | Low - hides wear |
| Polished Brass | Traditional, colonial | High - tarnishes without lacquer |
Coordination tip: Match door hardware to light fixtures and cabinet pulls in the same sightline. The finishes don't need to be identical brands, but should be the same family (brushed nickel with brushed nickel, not brushed nickel with chrome).
Types of Door Hardware
Passage Knobs/Levers
$15-$50No lock, for hallways, closets, and rooms without privacy needs. Both sides turn freely.
Privacy Knobs/Levers
$20-$60Push-button or turn-button lock on interior side, emergency unlock on exterior. Standard for bedrooms and bathrooms.
Dummy Knobs/Levers
$10-$30Non-functional, for aesthetics only. Used on the fixed side of double doors or closet bifolds.
Hinges
$5-$20/eachMatch finish to knobs. Standard doors use 3.5" hinges; heavy solid core doors may need ball-bearing hinges for smoother operation. Most doors need 3 hinges.
Door Installation Basics
Pre-Hung vs. Slab Doors
Pre-hung doors come mounted in a frame with hinges installed— ideal for new construction. You install the entire unit, shim level, and trim out.
Slab doors are just the door—you'll mortise hinges and drill hardware holes. Only practical for replacing a door in an existing frame of the exact same size.
Installation Steps (Pre-Hung)
- 1. Verify rough opening is 2" wider and 2.5" taller than door
- 2. Set door unit in opening, check plumb with level
- 3. Shim behind hinges and strike plate locations
- 4. Nail through jamb and shims into framing
- 5. Check door operation—should swing freely without rubbing
- 6. Install casing trim to cover gaps between jamb and drywall
- 7. Install door hardware (knobs, strike plate)
Avoiding Common Problems
Door Won't Latch
Usually caused by hinge sag or frame not plumb. First, tighten hinge screws (replace one with a 3" screw into framing). If still misaligned, adjust strike plate location or use an adjustable strike.
Door Swings Open/Closed by Itself
The jamb isn't plumb. Doors naturally want to swing to the low side. Re-shim the jamb to correct, or install a hinge pin door stop as a quick fix.
Uneven Gaps Around Door
Should be 1/8" gaps on sides and top, 1/2"-3/4" at bottom. Uneven gaps mean the jamb isn't square or the door is warped. Check jamb installation first.
Frequently Asked Questions
Should I upgrade all my existing doors to match the new ones?
If your existing doors are hollow core and you're installing solid core in the addition, you'll notice the quality difference. Many homeowners upgrade all interior doors during an addition for consistency. Budget $150-$300 per door (installed) for the upgrade.
Knobs or levers—which should I choose?
Levers are easier to operate with full hands or for those with grip difficulties, making them more accessible. Knobs are traditional and can't be accidentally caught by clothing. Match your existing style or upgrade everything to levers.
Do I need a fire-rated door between garage and house?
Yes—code requires a 20-minute fire-rated door (minimum 1-3/8" solid core steel or wood) between attached garage and living space. It must also be self-closing. Regular interior doors don't meet this requirement.
When should doors be installed relative to painting?
Install doors after walls are painted but before trim painting. This allows casing installation and caulking. Doors are then removed (pop hinge pins), painted separately for best results, and reinstalled.
Ready for the Next Step?
With interior doors installed, your addition has defined rooms. If your addition includes a bathroom, the next step is installing fixtures— toilet, vanity, and shower/tub.