How To Sew A Neat Lapped Zipper Installation
A lapped zipper is concealed beneath a fabric flap, so the teeth remain hidden when the garment is worn. This finish is common on skirts, trousers, dresses and some cushions because it looks polished without requiring an invisible-zipper foot.
The technique depends on accurate seam allowances rather than complicated machinery. A standard sewing machine, a zipper foot and careful pressing are enough for most medium-weight woven fabrics. Test the stitch length and tension on a scrap before working on the garment.
Choose a conventional dress zipper that is slightly longer than the opening. It can be shortened later, while a zipper that is too short may stop below the opening and create strain. Polyester thread is suitable for most cotton, linen, wool-blend and synthetic fabrics.
For Australian sewists, supplies are easy to find through Spotlight, Lincraft, independent shops in Melbourne and Sydney, or online retailers. Prices may vary with imported stock and seasonal sales, so check the zipper length and teeth type rather than choosing by colour alone. When buying equipment online, Australian Consumer Law generally protects consumers when goods are faulty, unsafe or not as described.
Choose The Right Zipper And Fabric
A lapped zipper works best in a stable woven fabric. Cotton poplin, denim, linen, suiting and medium-weight crepe are all manageable, while stretchy knits usually need a different construction. If the fabric frays heavily, finish the seam edges before installing the zip or apply a narrow strip of lightweight fusible interfacing.
Use a dress zipper with teeth suited to the garment’s weight. A fine coil zip looks discreet in a lightweight skirt, whereas a stronger polyester or metal zip suits denim or tailored trousers. In Brisbane’s humid weather, allow fabric and interfacing to settle fully after pressing so the opening does not distort as it cools.
Prepare Tools And Markings
Before sewing, measure the finished opening from the waistline or upper edge to the point where the zip will end. Mark this length on the fabric and transfer the same point to the zipper tape. If the garment has a waistband, include the seam allowance in your measurement so the slider will sit beneath the completed waistband.
A zipper foot is helpful because it allows the needle to sew close to the teeth without forcing the foot over them. A regular foot can work for basting, but it is less dependable for the final parallel rows.
Useful Supplies For The Job
- A standard dress zipper with a suitable length
- Matching thread and a fresh universal needle
- A zipper foot, seam ripper and fabric scissors
- Tailor’s chalk, pins or fabric clips
- An iron, pressing cloth and a stable ironing surface
Checks Before The First Stitch
- Confirm the seam allowance marked on the pattern
- Test the stitch length on a fabric offcut
- Check that the zipper slider moves smoothly
- Mark the opening endpoint on both fabric layers
- Finish or stabilise edges that fray or stretch
A reference for zipper sewing supplies can also help when assembling a basic repair and garment-making kit, although the zipper itself should always be checked for length and quality before installation.
Sew The Seam Below The Opening
Place the garment pieces right sides together and align the seam edges. Sew from the lower edge up to the marked zipper endpoint using the pattern’s seam allowance. At the endpoint, shorten the stitch length for the final few centimetres or reinforce the area with backstitching.
Press the seam open from the wrong side. Continue pressing the unsewn upper edges open as if the seam were complete. This creates a clear fold line and makes it easier to place the zipper accurately. Do not skip pressing, since a rippled seam will show through the finished lap.
Baste And Position The First Side
Close the zipper and place it face down on the right side of the garment, aligning its teeth with the pressed centre seam. The top stop should sit at the correct distance below the upper edge, allowing room for a waistband, facing or other finishing piece.
Pin or clip one zipper tape to the seam allowance only. Turn the garment to the wrong side and hand-baste or machine-baste the tape in place. Basting is safer than relying on pins because it holds the zipper straight while allowing you to remove it easily if the teeth drift.
Open the zipper and stitch the first tape close to its edge with the zipper foot. Sew from the top toward the bottom, keeping the seam line smooth. Stop before the slider, lower the needle, lift the presser foot and move the slider behind the foot. Lower the foot again and complete the row.
Create The Fabric Lap
Close the zipper and turn the garment right side out. Fold the fabric on the side that will cover the zipper teeth across the centre seam. In many skirt and trouser patterns, the wearer’s left side overlaps the right, but follow the pattern instructions if they specify another direction.
Press the fold gently, using a pressing cloth if the fabric is shiny or heat-sensitive. The fold should sit just over the teeth, hiding them without rubbing against the slider. Place pins perpendicular to the intended stitch line or use clips on bulky materials.
From the right side, sew a straight line parallel to the fold. This visible row secures the lap and forms the characteristic lapped-zipper finish. Keep the line consistent from the upper edge to the zipper endpoint, then stitch a short horizontal bar across the bottom if the pattern calls for a firm stop.
Secure The Second Tape
Open the zipper and turn the garment inside out. Move the underlap fabric away from the teeth and pin the remaining zipper tape to the other seam allowance. Check that the garment’s waistline, hem and seam motifs remain aligned before stitching.
Sew the second tape close to its edge, working carefully around the slider. The outer fabric should remain flat while you sew. If the two sides shift vertically, unpick the affected section and realign them rather than trying to disguise the mismatch with extra stitching.
Close the zipper and inspect the right side. The top edges should meet evenly, the lap should cover the teeth, and the lower end should not pucker. If the zip waves, remove the stitching and stabilise the opening with interfacing or a narrow strip of stay tape.
Finish And Test The Opening
Trim the zipper only after confirming that the slider stops well below the upper edge. If shortening a coil zipper, sew several firm bar tacks across the tape above the new endpoint, then cut away the excess below the tacks. Do not cut through the slider or the reinforced stopper.
Finish the waistband, facing or lining according to the pattern. A hook-and-eye above the zipper can take pressure off the top stop, especially on fitted skirts and trousers. In Australia, this is useful for garments worn in warm weather when fabric may be under greater strain from frequent washing and wear.
Run the zipper several times before pressing the completed garment. Wash or steam according to the fabric care label, then allow the garment to dry flat or on a suitable hanger. Avoid forcing a sticky slider; inspect for caught threads and trim them carefully.
Solve Common Installation Problems
A visible row of teeth usually means the lap is too narrow or the stitch line is too far from the folded edge. Repress the fold and resew closer to the teeth, but leave enough clearance for the slider to pass without catching. If the zipper is difficult to open, the needle may be too close to the teeth or the fabric may be pulling against the tape.
Uneven top edges often result from placing the zipper before marking the seam allowance. Unzip the garment, align the upper edges and secure the tape again with basting stitches. For slippery satin or lightweight rayon, use more basting and reduce the presser-foot pressure if the machine permits.
Puckering at the bottom can come from sewing over a closed zipper or stretching the fabric while attaching the second tape. Keep the fabric supported by the machine bed, sew with a steady feed and leave the zipper open when approaching the slider. A final press from the wrong side usually settles minor ripples without flattening the lap.