How to Reinstall Trim So It Goes Back Where It Came From

Why this matters

Removed trim that goes back loose, gapped at the top, or with old nail holes showing through fresh caulk is the most visible evidence a trade was in the room. It is also avoidable. The customer did not hire you to install trim, but they will judge the whole job by whether the baseboard looks like it did yesterday. Two mistakes cause most bad resets: driving nails back into the old holes, where they have nothing to grip, and nailing a board flat against a wall that is no longer flat because of the repair you made behind it.

This card picks up after removal. See related: How to Pull Baseboard Without Splitting It or the Wall, and How to Remove Door Casing and Crown for Reuse.

Where the new nails go

 FRONT VIEW OF A RESET BASEBOARD AT ONE STUD

            |<-- stud -->|  1 1/2 in wide, behind wall
  ----------+------------+---------  top edge of base
            |  o     x   |
            |            |   o = old hole, filled
   base     |            |   x = new nail, about 1/2 in
            |            |       beside the old one
  ..........|............|.........  top of bottom plate
       x    |  o         |    x
  ----------+------------+---------  bottom of base
  =================================  finished floor

  low nails go into the bottom plate, which runs the
  whole wall, so they can move anywhere along it

Two things that drawing teaches. High nails go into the stud, and a stud is only 1 1/2 in wide, so the new nail moves about 1/2 in to the side of the old one, which keeps it inside the stud with room to spare. Low nails go into the bottom plate, a horizontal 2x member that runs the full length of the wall, so they are not tied to stud locations at all and can move several inches to fresh wood. But the plate is low: its top sits 1 1/2 in above the subfloor, so over a 3/4 in hardwood floor only the bottom 3/4 in of the base has plate behind it. Measure the finished floor thickness before setting the low nails, or they go into air behind the drywall.

The steps

1. Clean the trim, the wall and the floor line. On each piece, pull any nail still in it through the back, slice off dried caulk along the top edge with a sharp chisel or knife, and scrape paint ridges off the back. On the wall, scrape the old caulk bead and any lumps of paint where the top edge will land. Vacuum the floor line. Why: a 1/16 in ridge of old caulk on the wall holds the top edge off by that much along the whole run, and a grain of grit under the bottom edge rocks a board. Skip it and you get a top-edge gap you then try to fill with caulk, which shrinks and shows.

2. Check the wall plane where you worked. Lay a straightedge across any drywall patch behind the trim line. A patch that sits proud, even slightly, is a hump the trim must bend over. Why: trim follows the wall; a hump makes the top edge stand off on both sides of it. Skip it and the board rocks over the patch and the nails pull the ends tight while the middle gaps. Sand or scrape the hump flat now. Sanding compound makes fine dust; use a damp sponge or a vacuum sander for a small patch.

3. Dry fit every piece by its number before any nail goes in. Reinstall in reverse of removal: at an inside corner, the square-cut piece goes in first and the coped piece second; at a scarf joint, the under piece, whose taper faces the room, goes in first, and the piece that laps over it second. Set all of a wall's pieces in place, push them tight, and look at every joint. Why: a joint that does not close in the dry fit will not close when nailed, and once nailed it is much harder to adjust. Skip it and you discover the problem with the first piece already fixed.

4. Nail into fresh framing, not the old holes. Start at a fixed end (the inside corner, or a door casing) and work along, unless the scarf order from step 3 puts another piece first. High nails into each stud, about 1/2 in to one side of the old hole, as drawn. Low nails into the plate, a few inches from the old ones. Angle each pair slightly toward each other so they lock the board against pulling straight off. Why: the old hole in the framing has been reamed out by a nail going in and coming out; a new nail in it has nothing to grip and backs out within a season. Skip it and the board looks fine today and has a gap by next winter. Hazard: a nailer fired through thin trim near the edge can blow out the side or deflect off a knot; keep your holding hand well clear of the nose and of the line the nail could travel, and wear eye protection.

5. Close the miters and copes. At an outside corner, put a thin line of wood glue on both miter faces, push the joint closed, and pin it with one brad through the corner from each side. At a cope, push the coped piece tight against its neighbor before the nail nearest the corner goes in. Why: an outside miter that is only nailed opens as the house moves through its seasons; glue holds the two pieces as one. Skip it and the miter opens to a visible line within a heating season.

6. Set and fill every hole, old and new. Set nail heads just below the surface. Fill the new holes and the old ones with paintable filler, slightly proud, then sand flush once dry. Why: the old holes are still in the trim's face even though no nail is in them. Skip it and the face shows two sets of holes.

7. Caulk the top edge to the wall. Run a thin bead of paintable caulk along the top edge and tool it with a damp finger. Do not caulk the bottom edge to a floating floor; the floor maker's instructions require it to move freely under the base. Why: the caulk line closes the small shadow the wall's own unevenness leaves, which is what makes trim look painted in place. Skip it and the original caulk line you cut at removal shows as a broken edge.

8. Touch up the paint. Where the trim was painted in place, the cut caulk line and filled holes need paint from the same can and sheen. A touch-up that flashes (a patch that reads glossier or duller than its surroundings) is its own problem; see related: How to Touch Up Paint So the Patch Does Not Flash.

Worked example: a reset after a wall leak

A plumber opened a 24 in wide by 16 in tall section of drywall at the floor of an 11 ft 4 in bedroom wall to repair a leaking line, and patched it. The base: 3 1/4 in painted pine in two pieces, P1 at 88 in from a coped inside corner to a scarf, and P2 at 48 in from the scarf to a mitered outside corner. 88 plus 48 is 136 in, which is the 11 ft 4 in wall. Finished floor is 3/4 in solid hardwood.

Step 1. Both pieces cleaned. P2's mitered end has a split about 1/2 in long running back from the tip of the miter, from removal. Rather than recutting the miter, which would shorten P2 and open a gap at the scarf, the tech works glue into the split, clamps it, and leaves it for the clamp time on the glue bottle while cleaning the wall.

Step 2. The straightedge across the patch rocks: the patch sits about 1/16 in proud along its lower edge. Dry fitting P1 over it confirms the cost, a gap of about 1/8 in at the top edge on both sides of the patch. The tech sands the hump with a damp sponge until the straightedge lies flat, and the dry-fit gap drops to a hairline.

Step 3. P1 is the coped piece at the inside corner, and the square-cut piece on the adjoining wall was never removed, so the corner is ready for it. The scarf sets the order between the two: P2's taper faces the room and P1's laps over it, so P2 goes in first. The tech dry fits both, with P2 still clamped, confirms the cope closes and the scarf meets, then waits out the clamp time before nailing anything.

Step 4. Studs at 16 in on center along 136 in: 136 divided by 16 is 8.5, so 9 studs. Nine high nails, each about 1/2 in beside an old hole. Low nails: the floor is 3/4 in, so the plate is behind only the bottom 3/4 in of the base; the tech sets the low nails about 3/8 in above the bottom edge, nine of them, each a few inches along from an old hole. Nails pair-angled. P2 is nailed first, its glued split holding, then P1 with its cope tight and its taper over P2's.

Step 5. The outside miter gets glue and a brad from each side. The scarf gets glue on the taper and a brad through it into the stud behind it.

Steps 6 to 8. Eighteen new nail holes, the three brad holes and the old holes filled; the top edge caulked; the cut paint line and filled holes touched up from the homeowner's leftover can.

The check that mattered. The tech nearly skipped step 2 because the patch looked flat. The straightedge found the 1/16 in hump; without it, the top edge would have shown a 1/8 in gap on either side of the patch, the exact spot the customer would look at because it is where the leak was.

When a piece will not reach or will not sit right

• The floor got lower. Carpet replaced with a thinner hard floor drops the base, which opens a strip of unpainted or unfinished wall above its top edge. Either add a shoe molding at the floor and set the base at its old height, or paint the exposed strip before reinstall.
• The floor got higher. A thicker new floor raises the base, so less of the base has plate behind it: over a 1 1/4 in floor only the bottom 1/4 in does, and over a floor 1 1/2 in thick or more, none. Move the low row up into the studs instead.
• A piece is short. A split end recut, or a corner that moved because of a patch, leaves a piece shy of its joint. Do not stretch it with caulk. Splice with a new or salvaged section, joined with a scarf (two tapers overlapping) over a stud.
• A cope will not close. A patch or new compound at an inside corner changes the corner's angle or fills it. Back-cut the cope a little with a utility knife or a rasp until it closes in the dry fit.
• Casing will not meet its jamb. If the drywall beside a door was patched thicker than before, the casing's wall-side edge sits proud and its miter opens. Take the patch down flat, not the casing.

How to verify

Run your hand along the top edge: no gap you can catch a fingernail in, and no point where the board moves under pressure. Look along the run from one end at a low angle; a straight line of top edge means no humps behind it. Every miter closed to a hairline, every hole filled, and the caulk line continuous. And the ticket notes any piece that was glued, spliced or replaced, because that is the piece that will tell the story if anything moves.

References

• Trade-standard finish carpentry practice for trim installation (nail placement into framing, glued outside miters, coped inside corners)
• Floating floor manufacturer installation instructions, for perimeter expansion space under base and shoe
• See related: How Trim Is Fastened: Baseboard, Casing and Crown; How to Patch Drywall After an Access Cut; Why a Repair Shows in Raking Light