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How toTrim & Molding

How do I install baseboard trim?

Let the trim sit in the room, mark the studs, and cut the longest wall first. Square-cut the ends that meet a door casing and cope or miter the corners. Tack each piece with two nails, check the fit, then add the rest, countersink the heads, fill and caulk. If the house is pre-1978 and you are pulling off painted trim, deal with lead dust first.

Free to ask. Local shops send quotes, and you pay only when you book one.

By Kasra Taheri, Founder, LoclisPublished

Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.

Step by step

Read when to stop and call a pro, further down this page, before you start.

  1. Step 1: Check for lead first

    If you are removing old painted trim in a home built before 1978, assume the paint may contain lead and use lead-safe work practices, because removing trim creates dust that may contain lead.[2]

  2. Step 2: Let the trim acclimate

    Stack the trim loosely in the room where it will be installed for a few days before cutting, so it settles to the room's humidity.

  3. Step 3: Mark the studs

    Find the wall studs with a stud finder and mark their centres on the wall just above where the top of the baseboard will sit.

  4. Step 4: Cut the first piece square

    Start on the longest wall with a square cut at each end, so the trim butts to a door casing or into a corner.

  5. Step 5: Cope the inside corners

    Cut the first piece square into the corner and shape the end of the next piece to match its profile with a coping saw, which stays tight if the corner is not exactly square.

  6. Step 6: Miter the outside corners

    Cut both pieces at matching angles so they wrap the corner, test the fit dry, then adjust the angle until the joint closes.

  7. Step 7: Tack with two nails

    Hold each piece in place and tack it up with only two nails, so you can still adjust it.[1]

  8. Step 8: Check the fit, then nail off

    With only a couple of nails in each piece, you can make small adjustments by holding a block against the trim and tapping it with a hammer, then add more nails into the studs.[1]

  9. Step 9: Set the nail heads

    Use a nail punch to countersink each nail head below the surface of the trim.[1]

  10. Step 10: Fill, caulk and paint

    Fill the nail holes with putty or spackle, caulk the top edge where it meets the wall, and paint.[1]

The short version

Baseboard goes on in a simple order: stack it in the room, mark the studs, cut and fit the longest wall first, tack each piece with two nails, check it, then nail it off, set the heads and finish the joints. The skill is in the corners and in not hurrying the fit.

Mitered pieces of white molding glued and taped into corner assemblies on a brown paper work surface
Photo: Tomwsulcer, CC0, via Wikimedia Commons

Before you start

If you are removing old painted trim, check the age of the house. If your home was built before 1978, it may have lead-based paint,[2] and removing trim creates dust that may contain lead.[2] If you are unable to determine the age of your home, it’s safest to assume the area you are renovating has lead-based paint.[2] EPA's do-it-yourself guidance says to use a spray mister or pump sprayer to mist areas before sanding, scraping, drilling, and cutting to keep the dust down.[2] Close off the room and keep the dust contained. Putting new trim over bare, new drywall carries no such risk.

EPA's RRP rule is aimed at people who are paid. It requires that anyone paid to perform work that disturbs painted surfaces in homes, childcare facilities and preschools built before 1978 be certified.[3] In general, the RRP Rule does not apply to homeowners doing RRP projects in their own pre-1978 homes. However, it does apply if you rent all or part of your home.[3]

Stack the new baseboard loosely in the room for a few days. Wood and MDF both move a little with humidity, and trim that has settled to the room's conditions stays put after it is nailed.

Cut and fit

Mark the studs first, so you know where each nail will go. Then start on the longest wall, with a square cut at each end where the trim meets a door casing or runs into a corner.

Inside corners are best coped. Run the first piece square into the corner, then cut the end of the next piece to follow the profile of the first. A coped joint stays tight when the corner is a degree or two off square, which most corners are. Outside corners are mitered: cut both pieces at matching angles, hold them together dry, and adjust until the joint closes. Cut slightly long and trim back, because it is easier to take off a sliver than to add one.

If the old trim comes off in the same job, take it off gently. ENERGY STAR's guide to removing trim says to cut the paint where the trim and the wall and jamb meet to prevent chipping or tearing.[1] That also saves the drywall paper from tearing away with the paint.

Nail it in stages

ENERGY STAR's trim instructions say to tack each one up with only two nails.[1] With only a couple of nails in each piece, you can make small adjustments by holding a block against the trim and tapping it with a hammer.[1] When the fit looks right, add the remaining nails into the studs, and stagger them so no two sit directly above one another.

Finish the joints

Set the nails so the heads sit below the surface: use your nail punch to countersink the nail 1/8” below the surface of the trim.[1] Fill the holes with putty to match the paint color on stained trim,[1] or spackle for painted trim.[1] Caulk the seam along the top edge, and any gap between the trim and the wall, with paintable caulk: ENERGY STAR recommends caulk for gaps a quarter inch or less.[1] A bigger gap usually means a wavy wall, and shimming or re-cutting looks better than a thick bead of caulk.

Let the caulk and filler dry, sand lightly, and paint.

Stop and call a pro if

  • The house is older and the paint may be lead-based. EPA recommends that homeowners hire a lead-safe certified contractor for projects in pre-1978 homes, and the RRP rule applies to you if you rent all or part of your home, operate a childcare center in it or buy, renovate and sell homes for profit.[3]
  • A nail hits something that is not wood. If you feel resistance that is not a stud, or a pipe or cable may be behind the spot, stop. Do not keep driving nails; a licensed plumber or electrician should check the wall.
  • The wall or floor is badly out of true. Gaps that keep opening up, a sagging floor edge or a wall that bows are problems with the structure, not the trim.
  • The trim is part of a bigger job. Moving or cutting into framing, rebuilding a stair or replacing flooring all go beyond baseboard.
  • You would rather not do the corners yourself. Finish carpentry is a defined specialty in Virginia, covering the installation, repair, and finishing of cabinets, sash casing, door casing, wooden flooring, baseboards, countertops, and other millwork.[4]

Getting help in Virginia

If you decide to hire it out, see whether to hire a carpenter to install trim and what crown molding costs in Virginia. Browse more home repair answers or the home repair services on Loclis.

When you are ready, describe the job once and licensed local pros quote it.

Common questions

Do I need to find the studs to nail baseboard?
Yes, it is worth the few minutes. Nails that go into the wall framing hold the trim; nails that only go into drywall pull loose. Mark the stud centres lightly above the baseboard line before the first piece goes on, and put your nails where the marks are.
Should I cope or miter inside corners?
Cope them if you can. A coped joint follows the profile of the first piece, so it stays tight even when the corner is a little out of square, which most are. Miter the outside corners, where the two pieces wrap around the wall.
How many nails should I use at first?
Only two per piece. ENERGY STAR's trim instructions say to tack each piece up with two nails, check the fit, make small adjustments by tapping against a block, and then add more nails.
What do I do about a gap between the baseboard and the wall?
Caulk handles small ones. ENERGY STAR lists caulk for gaps a quarter inch or less. A bigger gap usually means a wavy wall or a bowed board, and it is better to re-cut or shim than to fill it with caulk.
Is it safe to pull off old painted baseboard in an older house?
Not without precautions. EPA says an older home may have lead-based paint if it was built before 1978, and removing trim creates dust that may contain lead. EPA's RRP rule requires certification for anyone paid to disturb painted surfaces in a pre-1978 home, though in general it does not apply to homeowners working on their own homes.

Sources

  1. [1] Sealing Behind Window & Door Trim Project, ENERGY STAR, U.S. Environmental Protection Agency. Checked October 27, 2026.
  2. [2] Lead-Safe Renovations for DIYers, U.S. Environmental Protection Agency. Checked October 27, 2026.
  3. [3] Lead Renovation, Repair and Painting Program, U.S. Environmental Protection Agency. Checked October 27, 2026.
  4. [4] 18VAC50-22-30, Definitions of specialty services (Board for Contractors Regulations), Virginia Administrative Code, Board for Contractors. Checked October 27, 2026.

Want a pro to handle it?

Describe the job once. Licensed local businesses send quotes, and you pay only when you book one.