Baseboard and Casing Installation Guide
Reveals, nail sizes, coped and mitered corners, casing joints and window stool and apron, with a calculator for trim footage, sticks to buy and cost.
Doing this on a real job? Install baseboard and door casing: materials, tools and steps sized to your numbers.
Get the planCount baseboard, casing and quarter round for every room, with boards to buy, in the trim calculator.
How to install baseboard and casing, in six rules
- Install the finished flooring first.
- Case doors and windows with a 3/16 in reveal, then run the base into them.
- Cope inside corners; miter outside corners.
- Nail 2 to 2-1/2 in 15 or 16 ga into every stud, one high and one low into the plate.
- Glue and pin every miter.
- Set and fill nails, caulk the top edge, then paint.
Trim estimator
- Baseboard
- 55 ft
- 7 x 8 ft
- Casing
- 31 ft
- 5 x 7 ft
- Stool and apron
- 9 ft
- Nails and caulk
- ~145 nails, 2 tubes
Materials about $196 in primed MDF. Includes 15% on baseboard and 10% on casing for copes and mistakes.
Save this as a project: the cut list, a coped and mitered corner plan, the shopping list and a step checklist to tick off at the miter saw. Add the next room in the app and the whole-house trim job builds up in one place.
Project plan · built from your numbers
Install baseboard on 50 ft of wall and case 1 door
Run about 55 ft of baseboard (15% waste, doorways deducted) and 31 ft of casing for 1 door, with coped inside corners and mitered outside corners.
- Materials
- $196
- Time
- 1 day
- Level
- Easy
8 steps 8 tools 8 materials
- 1
Measure and plan the order
Measure each wall and sketch the room. Install the wall opposite the door first with square ends, so the copes face the way you enter and are hard to see.
- Measure every wall
- Plan the cope direction
- Mark studs on the wall
- 2
Case the doors first
Mark a 3/16" reveal on the jamb. Cut and nail the head casing, then the legs, gluing the miters.
- Reveal marked on all three sides
- Head piece nailed and glued
- Legs fitted tight
- 3
Case the windows
Stool first, notched around the jambs, then the side casings, the head and finally the apron under the stool, its ends returned.
- Stool notched and level
- Legs and head at a 3/16" reveal
- Apron length matches the head casing
01 · Your numbers
- Baseboard
- 55 ft
- Casing
- 31 ft
- Est. cost
- $196
02 · The plan
8 steps · 8 tools · 8 materials
5 more steps, the full tool list and a shopping list you can check off as you go.
03 · Finished
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Finished in 1 day · $196 DIY
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Casing joints: miter, butt, plinth block
| Joint | Look | Difficulty | Out-of-square jambs |
|---|---|---|---|
| Mitered (45 degree) | Clean, continuous profile; most common | Medium | Shows gaps on out-of-square jambs; adjust to 44 or 46 degrees and glue |
| Butt (craftsman head) | Flat legs under a thicker head with a cap | Easy | Very forgiving; square cuts only |
| Plinth block | Taller, thicker block at the floor; base and casing die into it | Easy | Solves base thicker than casing and uneven floors |
| Rosette (corner block) | Square block at each head corner, often with a bullseye | Easy | No miters to open; square cuts only |
Nail size by trim
- Casing, thin edge into the jamb: 1-1/2 to 2 in, 18 ga brad
- Casing, thick edge into the framing: 2 to 2-1/2 in, 16 or 15 ga finish
- Baseboard into studs and plate: 2 to 2-1/2 in, 16 or 15 ga finish (18 ga on thin MDF)
- Base shoe or quarter round: 1-1/4 in, 18 ga brad
- Miter pins (through the joint): 1 in, 18 or 23 ga
Reveal by casing style
- Standard colonial or ranch casing: 3/16 in
- Thin modern or flat stock: 1/8 in
- Craftsman or wide flat casing: 1/4 in
Baseboard height by ceiling
- 8 ft ceiling: 3-1/4 to 5-1/4 in
- 9 ft ceiling: 5-1/4 to 6 in
- 10 ft and up ceiling: 6 to 7-1/4 in
Corners not 90 degrees? Find the exact miter with the compound miter calculator.
Baseboard Installation Techniques
Critical Baseboard Corner Techniques
Like crown molding, baseboard inside corners should be coped, not mitered. Coped joints remain tight as the wood moves with seasonal changes. Outside corners are always mitered at 45 degrees.
Best Practice: Cope inside corners, miter outside corners, scarf joints at studs
Baseboard Corner Techniques
| Corner Type | Technique | Process |
|---|---|---|
| Inside corner | Cope the joint | Cut 45° miter, then cope profile with coping saw |
| Outside corner | Miter at 45 degrees | Both pieces cut at 45°, glue and nail together |
| Scarf joint (long runs) | 45° beveled scarf | Join over stud, upper piece overlaps lower |
Coping Baseboard Inside Corners
- 1.First piece: Install with square cut butting into corner
- 2.Cut miter: Cut 45° inside miter on second piece to expose profile
- 3.Mark profile: Darken profile line with pencil for visibility
- 4.Cope with saw: Cut along profile with coping saw or jigsaw
- 5.Back-cut: Angle cut back slightly for tight face fit
- 6.Test and adjust: Fit to first piece, sand high spots
Baseboard Nailing Pattern
- Locate studs: Use stud finder, mark with light pencil
- Spacing: Nail every 16 inches into studs
- Two nails per stud: One high, one low for secure hold
- Top nail: Into stud 1" from top edge
- Bottom nail: Into bottom plate 1" from bottom edge
- Nail size: 2" to 2-1/2" finish nails or 16-gauge brads
Base Shoe Molding
- Purpose: Covers gap between baseboard and floor, accounts for uneven floors
- Material: Quarter round or base shoe (1/2" × 3/4" typical)
- Installation: Nail into floor (not baseboard) to allow wood movement
- Inside corners: Cope base shoe like baseboard for tight fit
- Outside corners: Miter at 45 degrees like baseboard
- Nail spacing: Every 12-16 inches into floor or subfloor
- Alternative: Can caulk baseboard-to-floor gap instead if floor is level
Door Casing Installation
Door Casing Reveal
The reveal is the setback of the casing from the jamb edge. A consistent reveal creates a professional appearance and shadow line that defines the door opening.
Standard Reveal: 1/8 inch to 1/4 inch from jamb edge (3/16 inch is most common)
Door Casing Specifications
| Component | Measurement | Notes |
|---|---|---|
| Reveal from jamb edge | 1/8" to 1/4" (3/16" typical) | Consistent on all three sides |
| Head/side miter joint | 45 degrees | Must align perfectly on face |
| Side casing length | Floor to underside of head casing | Measure after head casing installed |
| Nailing - reveal edge | 2" finish nails into jamb | Every 12-16 inches |
| Nailing - outside edge | 2-1/2" nails or brads into stud | Every 16 inches |
Door Casing Installation Steps
- 1.Mark reveal: Set marking gauge to 3/16", mark jamb perimeter
- 2.Cut head casing: Square cut to length, add casing width × 2 + jamb width
- 3.Miter ends: 45° miters on both ends of head casing
- 4.Install head: Align to reveal marks, nail into head jamb and framing
- 5.Cut side casings: 45° miter on top, square cut on bottom
- 6.Fit miters: Adjust length until miter joints close perfectly
- 7.Install sides: Nail reveal edge into jamb, outside into framing
- 8.Pin miters: Brad nail through miter joint from side piece into head
Baseboard-to-Door Casing Transitions
Option 1: Returns (Most Common)
- • Baseboard dies into side casing at 45° angle
- • Create small return piece to finish end
- • Return wraps baseboard profile back to wall
- • Clean, professional appearance
Option 2: Plinth Blocks
- • Decorative block at base of door casing
- • Thicker and taller than casing
- • Baseboard butts into plinth (square cut)
- • Traditional, formal appearance
Window Casing Installation
Window Casing Components
Window casing differs from door casing by including a stool (interior sill) and apron. The stool projects beyond the casing, and side casings sit on top of the stool.
Key: Stool projects 3/4" to 1" past casing, side casings rest on stool surface
Window Trim Components & Measurements
| Component | Measurement/Specification | Purpose |
|---|---|---|
| Stool (sill) | Projects 3/4" to 1" past casing | Interior sill, decorative shelf |
| Stool length | Jamb width + 2× casing width + 2× projection | Extends past casings on both sides |
| Side casing | Rests on stool surface | Vertical trim on sides of window |
| Head casing | Miters to side casings at 45° | Top horizontal trim |
| Apron | Under stool, same length as head casing | Supports stool visually, covers gap |
Window Stool Installation
- 1.Measure width: Inside jamb width + reveal on each side
- 2.Measure length: Width + 2× casing width + 2× projection (3/4-1")
- 3.Notch corners: Cut notches to fit around side jambs
- 4.Test fit: Should sit level and tight to bottom jamb
- 5.Shim if needed: Level stool with shims underneath
- 6.Nail: Face nail into sill and shims with finish nails
- 7.Create returns: Miter profile at ends, glue return pieces
Window Casing & Apron
- Mark reveal: 3/16" from jamb edge on three sides
- Side casings: Bottom rests on stool, top miters to head
- Head casing: 45° miters on ends, same length as stool (visible portion)
- Install order: Stool first, then sides, then head, finally apron
- Apron: Cut to length of head casing, nail to wall under stool
- Apron returns: Miter ends and create small return pieces
Stool Profile Options
- Flat stool: Simple 1× material (1x4 or 1x6), easiest installation
- Beveled stool: Angled front edge, more formal appearance
- Bullnose stool: Rounded front edge, classic style
- Custom milled: Matching room trim profile, high-end look
- Thickness: 3/4" to 1-1/8" typical, thicker = more substantial
- Material: Pine, poplar, oak, or pre-primed MDF
Nailing Patterns & Techniques
Door/Window Casing Nailing
- Reveal edge: 2" finish nails into jamb every 12-16"
- Outside edge: 2-1/2" nails into framing every 16"
- Brads on outside: Can use 18-gauge brads for minimal holes
- Miter joints: Brad nail through from one piece into other
- Pre-drill hardwood: Prevents splitting near ends
- Set nails: Use nail set to countersink 1/16" below surface
Baseboard Nailing Pattern
- Into studs: Nail every 16" into wall studs
- Two nails: One high (into stud), one low (into plate)
- Near corners: Nail within 6" of inside and outside corners
- Nail size: 2" to 2-1/2" finish nails or 16-gauge
- Base shoe: Over a floating floor nail it to the baseboard so the floor can move; over nailed hardwood nail it to the floor
- No studs?: Use construction adhesive plus few nails
Pneumatic Nailer Settings
- Finish nailer: 15 or 16-gauge, 1-1/4" to 2-1/2" nails, for baseboard and casing
- Brad nailer: 18-gauge, 5/8" to 2" brads, for delicate trim and pinning
- Air pressure: 70-120 PSI typical, adjust for wood hardness
- Depth adjustment: Set so nail is flush or slightly below surface
- Test fire: Always test on scrap piece first to check depth
- Safety: Never bypass safety tip, keep away from body parts
Step-by-Step Installation Process
1
Measure & Plan Room Layout
- •Measure all wall lengths, noting door and window locations
- •Calculate baseboard material needed: add 10% for waste
- •Calculate casing material: each door needs approximately 17 linear feet
- •Each window needs approximately 20 linear feet including stool and apron
- •Plan installation order: typically baseboard first, then doors, then windows
- •Mark stud locations on walls before starting installation
2
Install Baseboard - Starting Wall
- •Choose least visible wall as starting point (often behind door)
- •Cut first piece to length with square cuts on both ends
- •This piece butts into corners - subsequent pieces cope to it
- •Locate studs along wall, mark with light pencil
- •Hold baseboard in place, check for gaps at floor
- •Nail top edge into studs, bottom edge into bottom plate
- •Nail every 16 inches: one nail high, one nail low
3
Cope Baseboard Inside Corners
- •Measure next wall length, add 1/4 inch for coping adjustment
- •Cut 45-degree inside miter on end that meets previous piece
- •Miter cut exposes baseboard profile - darken with pencil
- •Use coping saw or jigsaw to cut along profile line
- •Back-cut slightly (5-10 degrees) for tight face fit
- •Test fit against installed piece, adjust with rasp or sandpaper
- •When fit is perfect, install with same nailing pattern
- •Continue around room, coping each inside corner
4
Miter Baseboard Outside Corners
- •Measure to outside corner, cut both pieces slightly long
- •Cut 45-degree miters on both pieces (right and left)
- •Test fit - adjust length if needed for tight miter joint
- •If corner is not exactly 90 degrees, adjust miter angles
- •Apply wood glue to miter surfaces before installing
- •Nail both pieces, with nails within 6 inches of corner
- •Pin miter together by brad nailing through joint from both sides
- •Miter should be tight on face with no gaps
5
Install Base Shoe or Quarter Round
- •Install after baseboard is complete and before caulking
- •Follows same corner techniques: cope inside, miter outside
- •Cut pieces to fit between walls and corners
- •IMPORTANT: Nail into floor/subfloor, NOT into baseboard
- •This allows baseboard to move with humidity without gaps
- •Use 1-1/4 inch finish nails or 18-gauge brad nails
- •Nail every 12-16 inches along length
- •Set nails below surface, fill holes later
6
Install Door Casing - Set Reveal
- •Set marking gauge or combination square to 3/16 inch
- •Mark reveal line on all three sides of door jamb
- •Reveal line is where inside edge of casing will align
- •Keep reveal consistent on head jamb and both side jambs
- •This creates shadow line and professional appearance
- •Lightly mark with sharp pencil - will be covered by casing
7
Cut & Install Door Casing
- •Measure and cut head casing: jamb width + 2× casing width
- •Cut 45-degree miters on both ends of head casing
- •Position head casing on reveal marks, nail into jamb and framing
- •Measure side casings: floor to underside of head casing
- •Cut 45-degree miter on top, square cut on bottom
- •Fine-tune length until miter joints close perfectly
- •Install side casings: nail reveal edge into jamb, outside into framing
- •Pin miter joints with brads from side casing into head casing
8
Install Window Stool
- •Measure stool length: jamb width + 2× casing width + 2× projection
- •Typical projection: 3/4 inch to 1 inch beyond casing face
- •Cut notches at corners to fit around side jambs
- •Depth of notch: distance from inside edge of jamb to wall surface
- •Width of notch: equal to projection plus casing thickness
- •Test fit stool - should sit tight to bottom jamb and be level
- •Shim if needed to achieve perfect level
- •Nail through face into sill and shims with finish nails
9
Install Window Casings & Apron
- •Mark reveal on top and side jambs (3/16 inch typical)
- •Cut side casings: bottom edge rests on stool, top miters to head
- •Install side casings with same nailing pattern as doors
- •Cut head casing to length with 45-degree miters on ends
- •Install head casing, check miter joints close tightly
- •Cut apron to same length as head casing
- •Position apron under stool, centered on window
- •Nail apron to wall framing, pulling up tight to underside of stool
10
Caulk, Fill & Finish
- •Fill all nail holes with wood filler or painter's putty
- •Use nail set to ensure nails are countersunk before filling
- •Let filler dry completely (typically 30 minutes to 2 hours)
- •Sand filled nail holes flush with trim using 150-grit sandpaper
- •Caulk seam between baseboard and wall with paintable caulk
- •Caulk seam between casing and wall on doors and windows
- •DO NOT caulk coped joints - properly fit joints need no caulk
- •Small gaps in outside miters can be filled with caulk
- •Wipe excess caulk with damp finger or rag for smooth finish
- •Prime and paint all trim (2 coats for best coverage and durability)
Best Practices & Common Mistakes
DO:
- Cope all baseboard inside corners - never miter them
- Maintain consistent 3/16 inch reveal on door and window casing
- Nail base shoe to the baseboard over floating floors, to the floor over nailed hardwood
- Pin miter joints together with brad nails for tight fit
- Back-cut coped joints 5-10 degrees for tight face fit
- Caulk baseboard-to-wall and casing-to-wall seams before painting
- Pre-drill hardwood trim near ends to prevent splitting
- Use wood glue on all miter joints before nailing
DON'T:
- Miter baseboard inside corners (gaps open with wood movement)
- Install casing without marking reveal lines first (inconsistent appearance)
- Pin base shoe into a floating floor (it locks the floor and it buckles)
- Forget to back-cut coped joints (won't fit tight to first piece)
- Caulk coped joints (properly fit joints don't need caulk)
- Use too much caulk (creates messy appearance, hard to paint)
- Skip filling nail holes before painting (very visible after paint)
- Assume corners are square (measure and adjust miter angles)
Troubleshooting
- Miters gap at the heel or toe: the jamb is out of plane or the corner out of square. Shim behind the casing or recut at 44 or 46 degrees, then glue and pin.
- Wavy floor: scribe the base to the floor, or keep the base straight and let base shoe follow the floor.
- Base thicker than the casing: use a preacher block to scribe the end, back-bevel it, or switch to plinth blocks.
- Bowed wall at an outside corner: plane the drywall bead or shim behind the base, and bevel the miter to suit.
Choose a nailer with the nail gun selection guide, undercut door jambs for new flooring with an oscillating multi-tool, finish with the painting cheat sheet, and install the floor first with the laminate and vinyl plank guide. New doors go in before trim: exterior door installation.
Frequently asked questions
Do you install baseboard or casing first?
Casing first. The baseboard then butts into the casing (or a plinth block), so its length is set by the finished casing. Install finished flooring before either.
How big should the casing reveal be?
3/16 in is standard: enough to read as a deliberate step and hide a slightly uneven jamb edge. Thin modern casing looks better at 1/8 in and wide craftsman casing at 1/4 in. Keep it the same on every door.
Should I cope or miter inside corners?
Cope. A coped joint stays tight when the wall moves or the corner is not 90 degrees, while an inside miter opens up as the trim dries. Miter outside corners.
What size nails for baseboard and casing?
2 to 2-1/2 in 15 or 16 gauge finish nails into studs and plate for baseboard and the outer edge of casing, and 1-1/2 to 2 in 18 gauge brads into the jamb edge. Two nails at every stud.
Should I glue miters?
Yes, on outside baseboard corners and casing miters. A thin coat of wood glue plus a pin through the joint keeps it from opening with the seasons.
Base shoe or quarter round?
Base shoe is taller than it is deep and hides gaps at uneven floors with a slimmer look. Quarter round is a true quarter circle and stands out more. Either hides the expansion gap of a floating floor.
How much trim do I need per door?
About 17 linear feet of casing per side of a standard 32 to 36 in door: two 7 ft legs and a 3 ft head. Buy 7 ft casing lengths, three per side.
How long does it take to trim a room?
A first-timer should plan a full day for a 12 x 12 bedroom with one door and one window, plus a second day to fill, caulk and paint.
Going up to the ceiling? Angles, coping and a room cut list are in the crown molding installation guide.
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