Sewing technology for vents on a coat or midi skirt correct duplication and hem of the bottom

Processing the vents is a key step when creating coats, jackets and midi skirts with a straight or tapered silhouette. The slot not only provides freedom of movement, but also acts as an important aesthetic element. Proper duplication, precise selection of cut angles and correct hemming of the bottom ensure that the cut will not protrude, pull or deform during wear.

Anatomy of a spline: left and right sides, allowances and lobes

The slot is formed due to special allowances along the middle seam of the back or rear panel of the skirt. In women's clothing, the traditional overlap runs from right to left (the top vent is the right piece, the bottom vent is the left piece).

• Slot allowance width: For skirts it is 4-5 cm, for demi-season and winter coats - 6-8 cm.
• Hem allowance: For midi skirts it is usually 3-4 cm, for coats - 4-5 cm.
• Top corner vent: Placed at a 45° angle on the outer piece for a nice, easy hem.

Step 1: Duplicating the seam and hem allowances

To maintain a clear shape, the slot must be strengthened with adhesive materials before grinding down the parts.

1. Upper (overlapping) side: Duplicated completely, with the adhesive strip extending 1–1.5 cm beyond the fold line of the slot.
2. Bottom side: Glued with a strip of double fabric only along the hem allowance of the bottom and along the seam line itself to prevent stretching.
3. Bottom hem: Glued with a strip of doubler tape around the entire perimeter of the product.

Step 2: Processing the top corner and stitching the middle seam

Sew the middle back seam exactly to the top of the vent. Sew a 45° slant stitch across the top of the vent, securing the seam allowance to the overlapping side.

Press the middle seam above the vent. Iron the seam allowances toward the top (right) piece. At the point where the middle seam transitions into the slot, make a neat notch on the allowance of the lower part, not reaching the line 1-2 mm.

Step 3: Joining the lining and finishing the hem

Processing of the bottom with a slot in products with a lining is carried out “lockwise” or with the formation of a soft overlap (lining overlap of 1.5–2 cm).

Sew the lining to the vertical seam allowances, tucking the seam allowances inwards. Fold the corner of the bottom of the slot into an “envelope” (angle 45°), iron and stitch. Fold the bottom of the product and secure it with blind stitches to the main fabric or using a hemming machine.

Tailor's advice
The main reason for seam rupture at the top point of the spline is increased stress when taking a long step or when sitting. To avoid deformation, be sure tostitch the dolik reinforcement on the wrong sideor lay a finishing fastening stitch (with a corner or zigzag bartack) on the front side at the top of the vent. The proven ready-made patterns from our catalog will help you set the correct allowances for the slot in advance.

Frequently asked questions (FAQ)

What is the difference between a slot and a regular cut?
The cut is simply an unstitched seam with allowances pressed in different directions. A vent is a knot with overlapping allowances where one edge overlaps the other, completely hiding the legs in a static position.

How to prevent the vents on a pencil skirt from protruding?
Protrusion occurs when there is insufficient freedom of fit at the hips or when there is no duplication of the fold line of the vent. Make sure the hem allowance does not pull on the vertical seam.

Is it necessary to add lining over the vent in a coat?
Yes, definitely! An overflow of 1.5–2 cm in the lining along the entire bottom and at the top of the slots is necessary so that the lining does not pull on the main product when walking and during seasonal shrinkage of materials.

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