A side seam is a seam in a garment placed strategically to fall at the side of the garment. Seams are a way of joining pieces of fabric together. Nearly every garment contains some type of seam, and most have more than one seam. A side seam should fall in the middle of the side of the leg, approximately at the location of the ankle bone or at the side of the upper body, continuing on to the middle of the under arm.
Due to the fact that people are not the same size from front to back, this type of seam seam does not always fall perfectly in the middle of the two sides. For the average person, the back of the garment needs to have a greater material allowance when determining where a seam should fall. However, given that not all people fall within what has been deemed average size, seam allowances range greatly depending on the size the completed garment will be. If these dimensions are not allowed for prior to sewing the seam, the seam of the garment will either pull to the front or to the back.
While there are a number of different types of seams, the most commonly used kind is the flat seam. The reason the flat seam is often chosen is because it creates the least bulk of material at the point the two pieces of fabric are joined. The flat seam is the least visible of all the different types of seams, so it is the most common choice for a side seam.
When making a garment, a seam is often the most difficult part of the garment to sew. A seam must not only accommodate the width and breadth of the person wearing the garment. By falling in the true middle, it also must withstand the movement of the wearer. For this reason, the stitching used to create a side seam is often a very tight stitch. This seam is also often where a zipper will appear within a garment.
A side seam is not only used in sewing, but it is also used in knitting. The most common stitch used for side seaming in knitting is the mattress stitch, which alleviates any added bulk. Whether sewing or knitting, it is important to have a flat seam.