How to Cut Baseboard Inside Corners with Miter Saw: A Detailed Guide

Written by Milan Jara on 8th Jul 2022

Baseboard Molding

Looking for a guide on how to cut baseboard inside corners with a miter saw? Read on to learn more about DIY baseboard cutting using a miter saw.

Cutting a baseboard corner requires a moderate knowledge of woodworking skills and using the right tools. Use a miter saw to make precise crosscuts on your baseboards.

With precise steps and industry-leading materials, you will cut impressive baseboards. In this article, you will learn the correct accouterments and the precise steps to cut the inside corners of a baseboard with a miter saw. Plus, we'll give you DIY baseboard-cutting cheat sheet tips.

Supplies You’ll Need

Baseboards are best cut using a 10-inch blade miter saw. Miter saws are overly versatile and cut various boards for different joint types. Pair up a miter saw with a miter box to produce fine 45 degree angle cuts. Here’s how to use a miter box the correct way. Set yourself up for success by gathering the following tools:

  • High-quality miter saw
  • Miter box
  • Dust mask
  • Safety glasses
  • Tape measure
  • Woodworking pencil
  • Stud finder
  • Power brad nailer

Armed with the above tools and our steps, you can begin sawing away. But before we get down to cutting award-worthy boards, you should know the joint types you intend to cut.

Joint Types

There are four main joint types you will find in baseboards.

Miter Joint

Two beveled cuts make a miter joint at 45 degrees, forming a perfect corner. Miter joints withstand a lot of pressure.

Scarf Joint

A scarf joint is a vertical joint made by connecting tapered ends. You can make scarf joints by cutting the boards similar to a miter joint, only do it the opposite way.

Butt Joint

A butt joint is made by joining the two ends of the workpiece. You can connect the joints with any material, but you'll get the best results using clamps.

Coped Joints

A coped joint connects a butt joint to an end trimmed to fit the butt joint.

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How to Cut Inside Corners of Baseboards with a Miter Saw

Are your tools ready? Then you are all prepped to begin baseboard cutting. Briefly run through the following steps before working to get the hang of what to expect. Here's how to cut an inside corner for baseboards using a miter saw, step-by-step.

1. Gear Up

Before you begin sawing, wear a dust mask, goggles, and other protective gear to ensure a hazard-free job. Work in a clean, ventilated area.

2. Take the Exact Measurements

Precise measurements prevent you from wasting material and cutting the wrong corners. Using a tape measure, evaluate the length of the room in which you intend to install the cut pieces. You can draw a rough sketch of the room to estimate the amount of material to buy.

You need a high-quality baseboard to match up with the Styrofoam crown molding. We recommend aluminum or plastic baseboards that are a cinch to cut.

As you measure, use the stud finder to locate the studs and make accurate markings using a woodworking pencil. Remember to make precise markings on the baseboard piece. Put to task the saying, "measure twice, cut once".

3. Make Inside Corner Cuts

For this step, set the miter saw to 45 degrees and the miter to 0 degrees. You can check the degree gauge on the miter setup to set the right angles.

Use a pencil to mark the mitered corner angle and direction of the cut. Now that you have the correct markings, run through the saw into the board. Inside corners form a concave joint. Cut the board so that the backside of the board is a tad longer to avoid gaps when fitting the corners. Hold the saw firmly when cutting and never try to cut cross-handed.

If you use a plastic baseboard, you will want to ease the pressure to avoid melted plastic because of the saw and board friction. However, if there's unfortunate plastic melting, you can polish it up with sandpaper.

Cutting inside corners is the trickiest part of baseboard installation. You can make coped joints for inside corners that leave fewer gaps than butt joints and blend with urethane crown molding for a clean look. Use caulk to fill the gaps by the wall if they are 1/16 inch or less. However, if you set the saw right, you won’t have any gaps.

4. Cut the Second Piece

It is vital to nail (pun intended) the previous step. You will use the cut piece as a stencil to cut the mating piece. Set the saw to a 45 degree angle opposite from the initial cut. Hold the cut piece onto the other board and draw the correct markings using a pencil.

Make sure the cut piece joins perfectly with the adjoining one. Cut through the board using your miter saw as you did in the previous step - firmly but with no extra pressure. Remember to leave a little overhang that you can file or use sandpaper.

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5. Test-Fit the Baseboards

Here comes the moment of truth. This is the most nerve-wracking time for most DIYers and pro baseboard trim installers. Usually, you test-fit the boards at the end, but it is advisable to test for the boards as you cut.

You can easily spot errors and reposition your saw and cutting angles. Remember the overhang we told you to leave? Use a wood file to smoothen the edges if they snugly fit or 180-grit sandpaper. If you notice you are forcing them into place, saw off the extra length. Check your inside corners against this Bedford crown molding for preciseness.

You can cut material, but you can't add it. Hence the need for the slight extra length.

6. Conclude the Process

Everything is set, and you have your boards ready. Use the rough sketch of the building layout to fit the boards into place and nail them in; do not use nails longer than two inches to avoid damaging underlying ductwork or electrical wires. Clean the working area and enjoy your new boards. It is the perfect time to take snaps of your success.

Final Words

Installing baseboards is a straightforward task. Cutting the boards is the tricky part, especially for beginners. Armed with the right tools and following the steps in this guide, you can cut inside corners like a pro. Like other simple DIY woodworking tasks, you need the right tools and a can-do attitude to cut fine-looking baseboard molding every time.

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