What is the Corrugated Rib Stitch?

A Basic Two-Color Rib Pattern for Knitting

Corrugated Rib
Corrugated Rib worked over 24 stitches. (c) Sarah E. White, licensed to About.com, Inc.

Ribbing is a fantastic way to add a little bulk and texture to your knitting projects and the basic corrugated rib allows you to do so in two colors. The method is very easy and requires just a simple pattern of knit and purl stitches. It is the ideal way to practice strand knitting and prepare yourself for complex patterns in the Fair Isle style.

What is the Corrugated Rib?

The corrugated rib is not a stretchy rib and it has less elasticity than other ribbings.

It is, however, a popular decorative technique used on Fair Isle and other stranded knitting projects. It is an easy pattern that is a great way to practice working with two colors in the same row.

This pattern is particularly helpful when learning the correct tension for your strands on the back side of your work. You do not want them to be too loose or too tight and, by the end of a small swatch, you'll get a feel for the perfect tension.

Corrugated rib, like any other type of ribbing, can be worked on a wide variety or stitch multiples depending on the sort of ribbing you want to make. 

For example:

  • Work a 1x1 rib by repeating: knit 1, purl 1.
  • Work a 2x2 rib by repeating: knit 2, purl 2.
  • Work a 3x1 rib by repeating: knit 3, purl 1.

The thing that all corrugated rib stitches have in common is that the knit stitches are worked in one color and the purl stitches are in the second color. This is most commonly accomplished by working in the round because it is much easier to control the colors.

You will not be alternating which color is knit and which is purled from row to row. 

However, as we will see in the sample pattern, it is still a great pattern to work flat.

How to Make a Corrugated Rib

To practice the corrugated rib, you might want to stick with the simple 'double rib' in a 2x2 pattern.

To accomplish this, cast on stitches in a multiple of 2 in your first color (24 stitches makes a nice swatch). 

You will need two very important tips to work with two colors of yarn:

  • Make sure that all of your color stranding happens on the wrong side of the work. When working on a knit row, it is behind the work. When working the purl row, it is on the front of the work.
  • Make sure you don't pull your strands too tightly as you switch between colors. You can easily get too much tension in the strands and this will cause your fabric to buckle and bunch. This is particularly problematic when stranding yarn over stitch multiples great than 4.

Row 1: knit 2 in color A, purl 2 in color B. Continue this pattern across the entire row. 

Row 2: knit 2 in color B and purl 2 in color A. Continue this pattern across the row. 

To work the same pattern in the round, repeat row 1.

Using the Corrugated Rib

As with most Fair Isle patterns, the color stranding on the wrong side of the corrugated rib makes it less than ideal for two-sided projects like scarves and afghans.

It does, however, make a nice stitch pattern for projects like comfy throw pillows, bulky arm warmers (with a light weight yarn), and when designing your own Fair Isle patterns.

Use the corrugated rib wisely and you will find that it's a fantastic way to add a simple splash of color to your original knitting projects.