10 Jan 2018 • • by Heather Lou

Sewing a Waterproof Jacket with Seam Tape // Kelly Anorak Sewalong

kelly waterproofing with seam tape

When it comes to choosing a fabric for the Kelly Anorak pattern there are a lot of choices out there. If you are hoping to add a fully waterproof jacket to your me-made wardrobe but are hesitant because you've never sewn with technical fabrics before, don't be afraid! We had never sewn with this type of specialty fabric before working on this sewalong, and it was surprisingly easier than we thought! One of our pattern testers even sewed an amazing sample using a shower curtain. You can do this!


You will generally see fabrics described as waterproof vs. water resistant. What's the difference? Water-resistant fabrics will eventually become saturated but (you guessed it) they resist water for much longer than other substrates. Fabrics like nylon, ripstop and supplex fall under the water resistant category (ripstop is just nylon that's been woven to prevent fraying when torn). I made a nylon Kelly Anorak myself, and while it definitely held up in light rain, it tends to get soggy after sustained periods in heavier rain.

For a truly durable jacket, look for waterproof fabrics. These have been treated to completely resist water absorption, either with bonded layers or a chemical coating like polyurethane. A wax finish applied to heavier duty fabrics like canvas can also be waterproof; Otterwax is ideal for this purpose. Just note you may have to reapply the wax from time to time. Many commercially available waterproof fabrics are "breathable"; this means tehy are designed to repel water from the outside while allowing air to still pass through. This is critical for active use; nothing worse than breaking a sweat in a coat that won't breathe! If your fabric isn't breathable, I recommend inserting some grommets under the arm to let air circulate. The most common waterproof fabric is Goretex, although you may also see it described as Hyvent or Ultrex.

For our navy waterproof Kelly Anorak, we chose a specialty durable water repellant (DWR) 3-ply fabric called Ultrex, purchased from Seattle Fabrics (you can find more sources in our fabric post). Generally, waterproof or water repellent fabrics are classified as 2-ply or 3-ply. A 3-ply fabric has a built-in lining layer and is best for if you are sewing an unlined Kelly. When shopping online, sites often will tell you whether a fabric is waterproof or water repellant, and how windproof or breathable it is. If you aren't sure about a fabric, it's always a good idea to order a swatch. Some technical fabrics can be a little pricey, so it's nice to know what you can expect before ordering yardage.


The purpose of waterproof fabric is to repel moisture, which means you want to reduce the number of permeable holes in your fabric. This means absolutely no pins anywhere outside of seam allowances. When cutting, use pattern weights and a rotary cutter, or trace out your pieces using chalk. If your fabric is quite stiff or slippery, cutting in a single layer will make it easier to be accurate, and will let you get more yield from your yardage (I've been meaning to make Harry a waterproof dog coat to match mine with the leftover scraps).


If you are using a specialty waterproof fabric, you might be wondering the age-old question... to interface or not to interface? Many of these kinds of fabric are entirely synthetic and require a low iron. This can make it difficult to apply fusible interfacing, so you will want to test the heat tolerance of your fabric with a scrap to see if it will melt or curl under your iron. In our case, we used a very lightweight interfacing since our Ultrex was already a very sturdy fabric, and we used an organza press cloth between the iron and our waterproof fabric. The interfacing fused well even with a low heat setting and generally stayed in place. If you find your interfacing bubbles or won't fuse on low heat, you may consider using sew-in interfacing. The purpose of interfacing is to help stabilize the fabric, so it's always a good idea to add it when you can, especially to areas that will see a lot of stress (like where you'll be inserting grommets or snap buttons).

Kelly Anorak Sewalong // Sewing with waterproof fabrics // Closet Core Patterns


As I mentioned, you have to be careful pinning your fabric. Ideally, you want to avoid using pins, because each time you pierce the fabric with either a pin or a sewing machine needle you are inviting raindrops inside your jacket. We were lucky with our fabric - after piercing a swatch several times with a few sharp pins, and spraying the sample with some water, the back side was still completely dry. Rainwear win! If pin-pricking your fabric results in a leaky surface, here are a few tips:

  • Use Wonder Clips, simple binder or mini bulldog clips, or bobby pins to hold your pieces in place while sewing.
  • If pinning is absolutely necessary, pin within the seam allowance.
  • Use a microtex needle; they create sharp, small holes, perfect for piercing these sturdy fabrics

If your fabric sticks to the machine as you're sewing, considering investing in a teflon foot; this all allows the fabric to move smoothly through your feed dogs while you're sewing. In a pinch, you can use a layer of lightweight tracing paper in between the foot and the foot; just tear it away when your seam is finished.

In terms of pressing, it's really important to test a scrap to see how well it handles heat. Chances are you'll need to use low heat and a pressing cloth to prevent scorching. If your fabric wilts at the very sight of an iron, you may have to finger press your seam open instead.

We'll show you how we finished the seams of our waterproof Kelly Anorak. To begin, instead of pinning the front yoke to the front jacket, we used our trusty Wonder Clips.

Sewing a waterproof jacket // Kelly Anorak Sewalong // Closet Core Patterns

Flat fell seams are bulky and unnecessary with this waterproof fabric, and we didn't want the profile of a serged or zig-zag stitch to appear on the right side of the coat. Instead, we trimmed our seam allowances before pressing the seam down and topstitching, since the edges of this kind of fabric don't fray. The idea of trimming an entire jacket's worth of seam allowances is less than exciting, so if you have a serger, try removing the needle and thread and then using the knife to trim the seam down to 3/8" for you.

Sewing a waterproof jacket // Kelly Anorak Sewalong // Closet Core Patterns

After pressing the seam down towards the jacket hem, we went back to our regular machine and shifted our needle over to topstitch at 1/4" from the seam, so we'd catch the 3/8" seam allowance underneath.

Sewing a waterproof jacket // Kelly Anorak Sewalong // Closet Core Patterns


There is little point in investing in a waterproof or water-resistant fabric if you don't properly treat the seams to prevent water from seeping in. There are generally two methods of waterproofing seams: a liquid "glue" to seal all holes, vs. bondable tape applied with heat. If your fabric cannot handle any kind of heat, you'll have to use the liquid. If you can use an iron, I recommend the seam tape. It's neater and pretty fun to apply.

Seam sealers should be applied to both sides of the seam to be "truly" waterproof, but since they leave a slight residue, I would suggest using it on the wrong side only. This particular seam sealer is ideal for garment applications, but you can also find more heavy duty ones for tarps and tents.

For our waterproof Kelly, we finished all our seams with iron-on seam tape and it made for truly dry seams. You will want to practice adhering the tape with your iron on a scrap piece of waterproof fabric, to test what heat setting works best. The iron has to be hot enough to fuse the tape to the seam, but not so hot that it warps or melts the waterproof fabric. Position the tape over the seam on the wrong side of your fabric, and press for 10-20 seconds. When applying, press just a few inches at a time to make sure the tape is fusing well and is in the correct position. You'll also want to try to keep the tape outside of the seam allowances to reduce bulk and to avoid double layers of seam tape.

Sewing a waterproof jacket // Kelly Anorak Sewalong // Closet Core Patterns

A jacket sewn with waterproof or water resistant fabric doesn't need to be lined, but keep in mind you will be seeing the seam tape if you choose to apply it.

Hope you found this post helpful! I also recommend Rochelle Harper's book  Sewing Outdoor Gear a great resource for tips on seam finishes and using seam-sealing tape, as well as for learning about the different kinds of outerwear fabric available. Happy sewing!


Ready to sew? Read the next post in our Kelly Sewalong series. Get the pattern here.

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