Flat felled seams are a great way to finish seams on tailored and unlined garments and also on clothing that requires durability on the seams like jeans, pants, shorts, dungarees etc.

There are several ways to create flat felled seams: using a specialized industrial machines that stitch it with a double needle or using a quick and easy method with a domestic sewing machine.

You do not need any additional equipment for your sewing machine to create quick flat felled seams.
The basic supplies are:
– your sewing machine with a simple straight stitch;
– universal needle for your sewing machine;
– regular thread or (optional) topstitching thread;
– scissors;
– a small piece of fabric to practice;

Step 1

With the WRONG sides together match your pattern parts and stitch at 15 mm / 5/8 in using a medium length straight stitch (2-2.5 mm length stitch).

I recommend to use quilting or straight stitch foot for straight stitches. If you are using heavy weight fabric you might need to increase the seam allowance to 20 mm / 3/4 in (denim, wool) for better results.

Step 2

Press the seam well. To the left, to the right, from the wrong side of fabric. Decide on which side you want your seam to lap. As a general rule your side seams should lap towards the back. But there’s no a definite rule about that – you can choose any way you want. Press the seam closed towards the side you want your lap to be

Step 3

Trim the seam allowance that is on the bottom to 7 mm / 1/4 in.

Step 4

Press the top seam allowance under at 4-5 mm / 3/16 in. Your flat felled seam finished width from the previous stitching to the folded edge should be around 7 mm / 1/4 in. You can make it wider or thinner depending on your preference. Pin in place if needed.

Step 5

Topstitch the folded edge 1-2 mm / 1/16 in away from the edge with a regular or top stitching thread. You can use either a regular, straight stitch, quilting or topstitching foot for your sewing machine.

Now press your seams well. The seam is now finished.

You may find your seams to be very sturdy and har. That can contribute to poor fitting or be uncomfortable to wear. To make the seams softer and more flexible use the following methods:

1. Press them through the wet cloth both from the right and wrong side of fabrics.
2. Tap your seams with a little hammer or mallet.
3. Soak your garment in a vinegar solution for 30 minutes and then wash in warm/hot water. Dry your garment in a dryer with tennis balls.