How to Sew a Lapped Zipper

In this article, you will learn how super easy it is to install a lapped zipper. There are essentially two steps to a lapped zipper after you’ve partially sewn the center back (CB) seam: STEP 1, edgestitch the underlap to one side of the zipper tape.  And STEP 2, topstitch the overlap to the other side of the zipper tape. Done!

Vintage Factoid: Back in the day before there were invisible zippers, a lapped zipper was de rigueur in skirts and dresses.


Now that you’ve been introduced to the lapped zipper, let’s learn the anatomy of a zipper, a few bonus tips and then learn how to sew the underlap and overlap of a lapped zipper step-by-step with images…

Zipper Anatomy

All zippers share the same anatomy.

Garment zippers have two stops at the top; one stop at the bottom; two rows of teeth just like us; a chain;  a pull tab + slider; and tape on either side of the teeth or chain.

How to Install a Lapped Zipper

To get detailed descriptions of the parts and super bonus tips, please check out this article How to Sew a Centered (Slot) Zipper and come back!

Once you can identify the parts of a zipper, let’s learn about…

Zipper Feet

Ultimate Guide to Sewing Presser Feet

You can sew a lapped zipper using your standard (on the left) or narrow zipper foot (on the right).

RELATED: Check out this article How to Sew a Centered (Slot) Zipper to learn the pros and cons of these two feet when it comes to zipper insertion.

So now that you know the anatomy of a zipper and are privy to these bonus tips, it’s time to learn…

How to Sew a Lapped Zipper

You should know that a lapped zipper and centered (slot) zipper are first cousins. In fact, the start of the insertion process is exactly the same for each…

Lapped zippers are an invisible and super strong option for shorts, pants, skirts, and dresses!

Now, before we begin, I have to ask you to inhale and exhale slowly.  I would love it if you approach this skill building with confidence and just a tiny bit of patience…

Step 1. Mark the bottom of the zipper.

When you cut out the pattern pieces, make sure to transfer the notch at CB to the fabric of where the bottom stop of the zipper will be positioned.

In the image below, I used a blue water-soluble pen to mark the position of the bottom zipper stop for a size 10 garment; and I snipped the three notches that indicate CB.

How to Install a Lapped Zipper

Step 2. Interface the SAs of the zipper opening.

First, cut two strips of fusible tricot interfacing that is 1 inch wide and 1 inch longer than the zipper opening. You want the interfacing to overlap the zipper’s seam line.

Interfacing the zipper opening improves stability and prevents distortion and rippling over time!

Now, fuse one strip to the zipper opening at the garment FRONT and the garment BACK.

How to Install a Lapped Zipper

(In the image above, I am using black interfacing so you can clearly see how to interface a zipper opening. But if this was a real project, I would use white interfacing for this fabric)

As an extra assist, once the interfacing is fused to the zipper opening, you can go ahead and transfer the construction marking to the interfacing where the zipper’s bottom stop is to be positioned.

Sew easy tip: For silks, use silk organza — NOT fusibles!

Step 3. Finish the SAs of the CB seam (not shown).

Finish the SAs BEFORE you sew in your zipper. Choose the seam finish you prefer or what is appropriate for the fashion fabric used in the project. Options include zigzag, pinking, or serging.

But for accuracy and ease of insertion, do NOT trim off any of the SAs!

Sew easy tip: If I choose to pink the raw edges, I mark the 5/8 inch SA at the zipper opening BEFORE I pink the edges. This way I make sure I sew the CB seam using the correct SA!

Okay, it’s time to…

Step 4. Partially sew the CB seam.

Using a regular stitch length, with the right sides together (RST), sew the CB seam, from the hem up to the point where the bottom zipper stop is to take up residence.

Make sure to backstitch at the top of the CB seam — because that area will be under a lot of stress during the life of the garment!

How to Install a Lapped Zipper

In the image above, the pink dot points to where I backstitched!

Step 5. Press the SAs open. STOP!

This is where the lapped zipper diverges from the centered (slot) zipper.

Instead of pressing the SA open evenly along the 5/8 inch seam line as you do with a centered (slot) zipper, I want you to do this…

First, with the wrong side (WS) of the garment on the top, press the LEFT SA over by ½ inch all the way down — this will be the underlap.

Then, press the RIGHT SA over by 5/8 inch — this will be the overlap.

How to Install a Lapped Zipper

To ensure you get crisp, pressed folds, use a lot of steam or water spritz.

Step 6. Edgestitch the underlap.

At this point, I like to fold my garment in half so that the underlap is on the bottom and the overlap is on the top.

Then, align the fold of the underlap with the zipped up zipper until it kisses the zipper teeth like this…

How to Install a Lapped Zipper

In the image above, the SA of the overlap is on top.

Did you notice that the bottom zipper stop is positioned ever so slightly above the backstitching at the top of the CB seam?!

Once you’ve got the underlap kissing the zipper teeth, anchor the zipper to the SA with a single straight pin at a midway point.

Now, over at your machine, place the needle on the RIGHT side of the zipper foot. And starting two or three stitches beyond the bottom stop of the zipper, stitch forward and then backstitch.

For precision, I like to complete my first stitches manually!

How to Install a Lapped Zipper

Now, continue to SLOWLY edgestitch the fold as close to the zipper teeth all the way UP to the top edge, removing the pin when you need to…

Once you’ve completed stitching the underlap to the zipper tape, remove the garment from the machine and snip the thread tails away.

How to Install a Lapped Zipper

Okay, I have to ask you to…

Pause a moment and admire how pretty this completed half of the lapped zipper insertion is. ?

Step 7: Mark the topstitch guideline on the overlap.

Now, choose a marking tool that can easily be removed without a trace.

Then, from the RS of the garment and on the overlap, mark a short 3/8 inches in length topstitching guideline ¼ inch below the bottom and across from the CB seam.

And continue marking the topstitching guideline up the remainder of the overlap side of the zipper 3/8 inch from the fold like this…

How to Install a Lapped Zipper

Next, make sure that the stitching line of the underlap is covered ⅛ inch by the overlap all the way down the zipper opening like this…

How to Install a Lapped Zipper

And then, anchor the overlap in place with a straight pin

Sew easy tip: If you are sewing a lapped zipper into a curved seam, skip the pin and just carefully align the fold of the overlap over the stitching of the underlap as you stitch up the zipper opening.

Guess what?!

We’re ready to commit and finish this lapped zipper…

Step 8. Topstitch the overlap.

Position the needle on the LEFT side of the zipper presser foot.  Place your garment RS up under the zipper foot.

At the CB seam, lower your needle into the seam.

Stitch across two or three stitches and backstitch. Then, continue to stitch across until you reach the corner.

How to Install a Lapped Zipper
The needle is sunk into the seam.

Then, when you get to the corner, stop and pivot like this…

How to Install a Lapped Zipper

Now, lower the zipper foot and continue topstitching the overlap to the zipper tape all the way to top edge…

And voilà! You’ve sewn a lapped zipper!

So pretty!

Step 9: Finish the waistline or neckline edge.

Once your zipper is sewn into the CB seam, you can finish your neckline or waistline edge.

RELATED: Check out this article How to Sew a Centered (Slot) Zipper to learn a super bonus tip that can end up saving you a lot of frustration!

And one last thing…

How to Shorten a Too Long Zipper

Here’s an image from a Coats & Clark zipper packet on how to shorten a too-long zipper:

How to Install a Lapped Zipper

Sew easy tip: You can use an extra-thick thread like topstitching thread instead of a double-strand to whipstitch!

The End

Don’t you just love when things are sew easy?!

Now, you’ve met the first cousin of a centered (slot) zipper and you know how super easy it is to sew in an elegant, hidden lapped zipper.

My work here is done!

Anyhoo, remember this…

Life is the ultimate red carpet event! Dress for it!