- DIY Baseboards

Measuring:

Measure the linear footage of the room where the baseboard is to be installed. Make sure to measure every bend and curve in the wall as it goes completely around the room. Best practice is to add about 10% of baseboard to the measurement to account for waste from cutting.

Material & Tools Needed

Compound Miter Saw
Brad gun
Caulking Gun
Caulking (paintable latex)
Utility Knife

Planning

There are several different common cuts that can be made for the baseboard depending on the type of corner or bend in the wall. It is best to draw out a plan of the installation room and identify each of those corners. Knowing if there are two corner cuts that are required on a single stick of molding will be helpful to have forehand knowledge before the project gets started.

There are two styles of cutting the baseboard that will be explained. One is for the baseboard to be laid against the fence of the saw. The other is for it to be laid flat with the top or bottom edge of the baseboard touching the fence. It is important to have a compound miter saw for the latter version since the bevel feature of the saw will be utilized to make the cuts.

Where to Begin?

Commonly an inside-90 degree is the best place to start. For a basic room there will only be corners of that type, so it makes sense to have that be the starting point for any other type of room. If there is a design to the baseboard, which is not common, it would be best to start at the furthest corner from the entrance of the room.

Inside 90 degree

It is more common for inside corners of baseboard to be constructed with the coping saw method, but we prefer the mitered look. Not to worry, both methods will be explained.

Coping Saw Method

The Coping saw method is to run one stick of molding straight to the wall on one side but cut an inside-90 degree on the molding of the other side. The molding material that is exposed from the cut is cut away, making the edge match the pattern of the baseboard. It then rests on the straight piece of molding seamlessly since its been modified to follow the design pattern.

Run one running side of molding up against the wall until it stops against the opposing wall. The bottom of the molding will be resting on the floor but make sure that it is pushed up against the wall and vertically level. Nail it into place.

Version: Vertical on Fence

Take the second running side of molding and cut an inside-90 degree corner. This is accomplished by setting the miter angle of your saw to 45 in the direction of the running molding. If the baseboard is coming from the right, the miter angle should be moved to the right, or 3 o'clock. The molding should be stretching to the right while the side to be cut is on the left at the saw blade. Hold the molding vertically straight against the fence of the saw and make the cut.

Version: Flat on Saw

In the event that the baseboard is too tall for the saw to be able to cut all the way through, this the alternative:

Set the miter angle of the saw to zero and lay the baseboard flat on the saw with the top touching the fence. Now set the bevel angle to 45 in the direction of the running molding. For baseboard that come from the right, the bevel should also angle to the right.

To test our results, use the example from before of coming from the right. If done correctly, the cut will be on the left-side of the length of molding. At the spot of the cut, the molding will be long at the back and to the left. For those coming from the left, the result will be long in the back and to the right.

Coping

Lay the newly cut baseboard flat on a table and use a coping saw to cut away the exposed material of the cut. The cut will begin with the pattern on the front of the baseboard straight through to back of the baseboard. Use a round file or rolled-up square of sandpaper to wear away frayed ends for a better fit.

Fit that molding up against the already installed stick of baseboard until both or lined up and snug and nail into place.

Miter Cut Method

A miter cut corner is where both baseboards are cut at an angle so that they meet together in the corner to complete the corner. The seam that is created is a little more pronounced yet symmetrical.

Version: Vertical on Fence (inside-90 degree)

Adjust the miter angle of the saw to 45. The turn-of-the-saw direction will line up with the side in which the molding is arriving. Moving the saw to the right (3 o'clock) for the right-side baseboard and left (9 o'clock) for left-side. While holding it against the fence make the cut.

Version: Flat on Saw (inside-90 degree)

Begin by setting the miter angle to zero (the center of clock) and the bevel angle to 45 on the left (10 o'clock). For the run of baseboard that is coming from the left, have the top of the design touching the fence and make the cut. For the right-side run of molding, have the bottom of the design touching the fence and make the cut.
Left - Top Touching Fence
Right - Bottom Touching Fence

This might look odd since the run of molding that is from the "right-side" will be stretching to the left on the saw, but remember that it is upside-down.

If done correctly, the angled cuts should come together to create an inside-90 degree corner that lines up and is snug. Insert them into the corner, push them up against the wall making sure that they lay level vertically, and then nail them both into place.

Outside 90 degree

Lay the baseboard in place against the wall. Make a pencil mark on the top of the baseboard where it meets the corner of the wall. This applies for both sides of the baseboard that are being installed.

The instructions are the same for the inside-90 degree corner as before, with the exception being that the angles are flipped. Being an outside corner, the end results need to be the opposite of what was needed before. For the final version, the cut board should be long in the front.

Version: Vertical on Fence (outside-90 degree)

Adjust the miter angle of the saw to 45. Since this is for an outside corner, the saw will be pointed in the other direction to the side of the molding that is arriving. The saw to the left (9 o'clock) for the right-side molding. That saw to the right (3 o'clock) for the left-side molding. While holding it against the fence make the cut. Move the angle to the other side of 45 to cut for the other side of molding.

Version: Flat on Saw (outside-90 degree)

Begin by setting the miter angle to zero (center of clock) and the bevel angle to 45 to the left (10 o'clock). For the run of baseboard that is coming from the right, have the top of the design touching the fence and make the cut. For the left-side run of molding, have the bottom of the design touching the fence and make the cut.
Left - Bottom Touching Fence
Right - Top Touching Fence

This might look odd since the run of molding that is "coming from the left" will be stretching to the right on the saw, but remember that it is upside-down.

When done, the angled cuts should come together to create an outside-90 degree corner that lines up and is snug. Insert them into the corner, push them up against the wall making sure that they lay level vertically, and then nail them both into place.

Non-90 degree angles

There are going to be corners that are not 90 degree. To create corner cuts for these other angles, the angle itself needs to be measured using an angle finder. For the 90 degree cuts that have been explained already, the saw was set at 45, which is half of the wall angle of 90. Treat every less-than-90 degree angle by halving the measurement and using that value as the setting for the saw.

For angles that are more than 90 degree, you will need to subtract that angle from 180 degree and then halve the result.

Inside 135 degree

A common corner angle that is greater than 90 degree is the 135 degree corner. The difference of 180 degree and 135 degree is 45 degree and half of that is 22.5 degree, so to make 135 degree corners, the saw would need to be set at 22.5 degree.

Version: Vertical on Fence (inside-135 degree)

Set the miter angle of the saw to 22.5. The turn-of-the-saw direction will line up with the side in which the molding is arriving. Moving the saw to the right (3 o'clock) for the right-side baseboard and left (9 o'clock) for left-side. While holding it against the fence make the cut.

Version: Flat on Saw (inside-135 degree)

Set the miter angle to zero and the bevel angle to 22.5 on the left (10 o'clock). For the run of baseboard that is coming from the left, have the top of the design touching the fence and make the cut. For the right-side run of molding, have the bottom of the design touching the fence and make the cut.
Left - Top Touching Fence
Right - Bottom Touching Fence

Outside 135 degree
Version: Vertical on Fence (outside-135 degree)

Same as the inside angle just the opposite.
Miter angle: 22.5.
Left-side of Baseboard: Saw is on the right (3 o'clock).
Right-side of Baseboard: Saw is on the left (9 o'clock) for left-side.
Hold against the fence and cut.

Version: Flat on Saw (outside-135 degree)

Miter angle: 0
Bevel angle: 22.5 to the left (10 o'clock).
Left-side of Baseboard - Bottom Touching Fence
Right-side of Baseboard - Top Touching Fence

Bullnose Corners

It is popular for corners to have rounded features to them. They are not an exact 90 degree corner, that is, a sharp turn. They can be rounded, with a slow turn called a bullnose corner. Straight cuts cannot be made for those corners.

Our solution is to cut corners with a third transition piece. It calls for three cuts yet with these three parts of molding, it can round the corners without looking out of place. This transition piece would require that the backside handle about 83% of the radius of that corner. Also the lengths of baseboard would need to extend beyond the curve of the corner to meet with the transition piece. This extension should be half the width of that transition piece.

For our installation examples, we are using a wall that has a 1-inch radius bullnose corner. At 83% it would mean the transition piece would be 13/16" wide and the the baseboard about 3/8" longer into the curve.

Outside 90 degree with Bullnose
Version: Vertical on Fence (outside-90 degree, bullnose)

Version: Flat on Saw (outside-90 degree, bullnose)

Begin by setting the miter angle to zero (center of clock) and the bevel angle to 22.5 to the left (10 o'clock). For the left-side run of molding, have the bottom of the design touching the fence and cut. For the run of baseboard that is coming from the right, have the top of the design touching the fence and cut.

For the transition piece, it can be cut from a spare piece of baseboard. The bevel angle is to remain at 22.5. Starting at the left side of that spare bit, as if the molding were coming from the right, make the cut with the top of the baseboard at the top against the fence.

Since the width has been calculated as 13/1", that will be measured on the backside of the baseboard. Mark that measurement before cutting and be sure to factor in the width of the blade itself. Only cut to the mark.

Flip it around, with the bottom against the fence, and cut again.

Inside 135 degree with Bullnose
Version: Vertical on Fence (inside-135 degree, bullnose)

Version: Flat on Saw (inside-135 degree, bullnose)

Begin by setting the miter angle to zero (center of clock) and the bevel angle to 11.25 to the left (10 o'clock). For the left-side run of molding, have the top of the design touching the fence and cut. For the run of baseboard that is coming from the right, have the bottom of the design touching the fence and cut.

Again the transition piece may come from some scrap baseboard. The bevel angle is to remain at 11.25. Starting at the left side cut with the bottom of the baseboard against the fence.

Mark 1-inch on the back of the molding and cut with the top against against the fence.

Outside 135 degree with Bullnose
Version: Vertical on Fence (outside-135 degree, bullnose)
Version: Flat on Saw (outside-135 degree, bullnose)

Use adhesive in between any joints in the molding for expand and contract.

When installing the last piece of a long run leave it 1/1" long to apply pressure to other pieces.

Painting

The molding will have a primer already when purchased. Even though a good number of paint types have been tested to work with the polyurethane material, it is best to test the paint before-hand. This is still an ideal practice even with strong confidence in a brand. Some manufactures modify their formulas over time which might not provide the trusted results that are typical.

Apply the paint to a small area of the molding allowing it to completely dry. If it looks and feels as expected after drying, you can continue with the rest of the molding. If not, remove the paint and apply a different brand.

Paint the molding before installation, but keep in mind that touch-ups with the paint may be necessary after completion.

Finish Work

Now that the adhesive has dried, it is time to finish it up.

For the temporary screw option, carefully remove the screws. Use Spackle to fill in the holes and touch-up paint to match the rest of the molding.

For the permanent option, apply Spackle over the screw or nail heads, and touch-up paint to finish it.

Apply a bead of caulking along the edge where the molding meets the ceiling. Use a damp rag to wipe away any excess caulking.