How to Put Up Crown Molding With Corner Pieces
To put up crown molding with corner pieces, mark your layout, dry fit each corner block, then glue and nail the blocks to the wall and ceiling first. Cut the straight runs square at each end so they butt into the blocks, and nail them into solid framing. Fill the nail holes and caulk the seams for a clean finish.
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Metabo HPT NT65M2SLightest pro nailer
Bostitch BTFP71917What corner pieces do and when to use them
Corner pieces, often called corner blocks, are pre-made inside and outside corners that match a certain crown profile. They remove the hardest part of the job, which is cutting tight angled corners that fit perfectly. Instead of angled cuts at every corner, you cut each straight piece square and let the block hide the joint.
Corner blocks work best when the block and the molding come from the same profile family. If the sizes do not match, you will see a step at the seam. Check that the block projection and height line up with the molding before you start.
They also help in older homes where walls are not perfectly square. A block gives you a fixed corner shape, and small gaps at the edges are easy to caulk. If you want to cut your own corners instead, the next sections cover that too.
Tools and materials to gather
You do not need a large kit, but you do need the right basics. A stud finder and a pencil let you mark the framing, and a tape measure and level keep your lines straight.
- Corner blocks (inside and outside) and matching crown molding
- A miter saw for clean square and angled cuts
- A finish nailer, or a hammer and finish nails
- Construction adhesive or a quality paintable caulk
- Wood filler, a putty knife and paintable caulk
- Stud finder, tape measure, pencil and a level
- Safety glasses, hearing protection and a dust mask
- A stable ladder or work platform
Choosing a nailer for crown
Crown molding sits at an angle between the wall and ceiling, so the nails need to reach the framing behind the drywall. Most installers pick a 15 or 16 gauge finish nailer. Thicker 15 gauge nails hold heavier crown well, while 16 gauge nails leave smaller holes that are easy to fill. Skip thin 18 gauge brads on large crown, because they may not hold.
An angled magazine helps the nose fit into tight corners. On our best nailer for crown molding page, the Metabo HPT NT65MA4 is a 15 gauge angled nailer that weighs 4.2 lb and accepts nails from 1-1/4 in to 2-1/2 in. If you want less weight to hold overhead, the Metabo HPT NT65M2S is a 16 gauge nailer at 3.7 lb, which is the lowest weight on that page. It has a straight magazine, so corners need a bit more care.
Weight matters because you hold the tool above your head for long stretches. You can compare gauge, weight and nail length side by side on the page before you decide.
Step-by-step: installing with corner blocks
Take your time on the layout. A few careful marks will save you from refitting pieces later.
- Find and mark the wall studs and the ceiling joists with a stud finder. Lightly mark the spots so you know where to nail.
- Hold a piece of molding in place and mark its bottom edge on the wall. Use a level to connect the marks so you have a guide line around the room.
- Dry fit each corner block against the wall and ceiling. Check that it sits tight and that the edges line up with your guide line.
- Apply a bead of adhesive or caulk to the back edges of the block. Press it firmly into the corner and tack it with two finish nails to hold it while the adhesive sets.
- Measure each wall between the blocks. Cut the straight pieces square at both ends, and cut them slightly snug so they push in without gaps.
- Set each piece in place, butt the ends against the blocks, and nail into the studs along the wall edge and the joists along the ceiling edge.
- Fill the nail holes with wood filler, sand lightly, caulk the seams, then paint.
How to join crown molding on long walls
Sometimes one wall is longer than a single piece of molding. In that case, you need to join two pieces end to end. The standard way is a scarf joint, which is two matching 45 degree cuts that overlap each other. Place the joint over a stud so both pieces can be nailed close to the seam.
Glue the faces of the joint, press the pieces together and nail on both sides. Sand the seam lightly after the glue dries, then fill and caulk. A scarf joint hides small movement better than a straight butt joint, which can open up as wood changes with the seasons.
If you are not using blocks, corners need their own joints. The table compares the common options.
| Corner method | How it works | Skill level | Best for |
|---|---|---|---|
| Corner blocks | Pre-made block hides the joint; straight runs are cut square | Beginner | Rooms with uneven walls and matching profiles |
| Mitered corner | Two angled cuts meet at the corner | Intermediate | Square corners and simple profiles |
| Coped inside corner | One piece is cut to match the face of the other | Advanced | Inside corners where walls are not square |
| Scarf joint | Two 45 degree cuts overlap along a wall | Intermediate | Joining pieces on long walls |
Finishing and safety notes
Fill each nail hole with wood filler, let it dry, and sand it smooth. Run a thin bead of paintable caulk along the top and bottom edges of the molding and wipe it with a damp finger. Paint after the caulk has cured.
Work safely. Wear safety glasses whenever you cut or nail, and wear hearing protection around a miter saw or air compressor. Use a ladder that is the right height, keep three points of contact, and do not lean away from it. Never reach past your safe range to place one more nail.
Before nailing, think about what is behind the wall. Electrical wires and pipes can run near the ceiling line, so do not drive long nails without checking. Disconnect the air hose before clearing a jam or leaving the tool, and keep your fingers away from the nose of the nailer.
Frequently asked questions
Do I need to cut angles if I use corner blocks?
No. With corner blocks, you cut the ends of each straight piece square and butt them against the block. You only need angled cuts if you are joining pieces with a scarf joint.
Should I glue corner blocks or only nail them?
Use both. Adhesive or caulk gives the block a strong bond to the wall and ceiling, and a couple of finish nails hold it in place while the adhesive sets.
Can I use a hammer instead of a nailer?
Yes, but it is slower and harder to do overhead. If you hammer, use a nail set to sink the heads below the surface so you can fill the holes cleanly.
What if the molding does not meet the block flush?
Small gaps can be closed with paintable caulk. If the gap is large, recut the piece or check that the block and molding profiles actually match.