Triple Rail Quilt Block Pattern

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How to Sew a Triple Rail Quilt Block

The Triple Rail quilt block is a simple yet versatile strip-piecing design that adds great visual interest to any quilt. Experiment with different color combinations to create unique and eye-catching results.

Materials Needed

• Fabric (at least 3 different colors)
• Quilting ruler
• Rotary cutter
• Cutting mat
• Sewing machine and thread
• Iron

Step-by-Step Instructions

1. Cut three strips of fabric in different colors, all the same width and slightly longer than your desired finished block size. For a 12" finished block, cut three strips that are 3" wide and 13" long.
2. Place the strips right sides together with top edges aligned. Sew the strips together along the top edge with a ¼" seam allowance. Press the seams open.
3. Cut the sewn-together strips into segments the same width as the individual strips. For 3" wide strips, cut 3" segments.
4. Sew two segments together along the long edge, right sides together with seams aligned. Press the seams open. Repeat with the third segment.
5. Sew the two pairs of segments together along the long edge, right sides together with seams aligned. Press the seams open.
6. Trim the block to the desired finished size, ensuring all edges are straight and corners are square.
7. Repeat to make as many Triple Rail blocks as needed for your quilt.

Four Patch Technique

The secret to the perfect four patch is pressing seams so they butt together when joined. You can make the four patch by cutting individual squares (great for scrappy quilts) or using pre-joined strips for speed. Both methods are covered below.

Method 1: Individual Squares

1. Cut two A squares and two B squares in your required size.
2. Using chain piecing, join one A square to one B square, right sides together, with a scant ¼" seam allowance. Press toward the dark fabric.

This is your result:

This is also the result of cutting across pre-joined strips. For the strip method, the width of the unit cut from pre-joined strips equals the width of the original strips.

3. Press all seams toward the dark fabric so they butt up neatly.
4. Place the two A/B units right sides together, butting the seams. Pin if needed, then join with a scant ¼" seam allowance and press.

Wider Application

You can apply this technique to all kinds of four patch blocks. As long as a block has a 4×4 grid — no matter how many pieces — the basic principles apply. Keep pressing seams in pairs of opposite directions and piecing becomes easy.

All of the following blocks have 4×4 grids and can be pieced as a four patch:

How to Resize Quilt Blocks

The first step in modifying any quilt block is to decide on your finished block size. You can base this on doubling a pattern, cutting it in half, or working with your available fabric.

Note: When working from a pattern's cutting instructions, remove the seam allowance before scaling. For example, if your pattern calls for 3½″ squares, subtract the seam allowance (½″), double the finished size (3″ → 6″), then add the seam allowance back (½″) — giving you a 6½″ cut piece.

Resizing Square Blocks

Add ½″ to your finished block measurement. For a 4″ finished square, cut a 4½″ square of fabric.

Resizing Rectangular Blocks

Add ½″ to both the length and width. To double a 3″ × 4″ block, cut a 6½″ × 8½″ rectangle.

Resizing Half-Square Triangle Blocks

Add 7/8″ to the desired finished block size. For a 4″ finished HST block, cut 4⅞″ squares.

Resizing Quarter Square Triangle Blocks

Add 1¼″ to the desired finished block size. For a 4″ finished block, cut 5¼″ squares.