Sewing Tips for Waterproof Breathable Fabrics

If you are not sure what a waterproof breathable fabric is, read our post on Demystifying Technical Fabrics.  Waterproof breathable fabrics are impervious to rain and yet let out water vapor (sweat), but you want to use them the correct way and try to keep them waterproof so they will function well when you are wearing them.

When using any coated waterproof breathable fabric, the coated side should be to the inside, or to the wrong side of garment.  However, for fabrics like Dintex, the softer side should be to the inside of the garment and the waterproof side to the outside.  

Tips for Sewing with Waterproof Breathable Fabrics:

• For coated fabric, the coating must be protected from abrasion by lining your garment, so if your pattern does not call for a lining, you will need to add one.  We will go through this in the next blog post.
• When cutting out and sewing waterproof fabrics, pin pieces within the seam allowances to prevent punching holes in the coating or waterproof layers.
• Use a storm flap under or over all zipper openings.
• Use a small (size 11 or 14) sharp needle.
• Stitch seams with a straight stitch and seam seal all stitching lines for waterproof seams (see below).
• Coated fabrics do not ravel, so zigzagging or serging seams is unnecessary and inhibits seam sealing.
• A waterproof coating on fabric somewhat alleviates the importance of grain. For loose-fitting garments, you can lay pattern pieces on crosswise grain if this saves fabric.
• Choose a pattern with as few stitching lines as possible. 

There are several options for sealing your seams:

• Iron-on seam sealing tape.  Drawbacks are that you have to use high heat (which is hard with some fabrics because high heat can damage them).  Applied to wrong side of fabric/garment.
• Canvas seam sealer.  Is painted on; can be used on many types of fabric and keeps the look and feel of the fabric.
• Seam Grip, Fray Check, and Seam Cement are also options, depending on your fabric, how you want the finish to look, and how you will care for your garment/bag/project.

Tips for Using Waterproof Breathable Fabrics for Lining

If you are using a non-waterproof outer fabric, you may choose to increase waterproof capability of your garment by adding a waterproof-breathable lining.

1. Cut lining for main body and sleeves of garment from pattern, using a waterproof-breathable fabric.
2. Use waterproof-breathable fabric for interfacing in collar, pocket flaps, front storm flap, and sleeve cuffs.
3. Seal seams of lining fabric with seam sealer before attaching to outer shell.  (Apply seam sealer on wrong side of fabric, on each side of and down the center of seams. Two thin coats of sealer are more flexible than one thick coat.)
4. Make buttonhole openings or insert grommets for drainage near bottom of
   outer shell fabric at these locations:
   • Near sleeve seam just above cuff or elastic casing.
   • Near side seams on front and back of garment.
   • At center back.