How to Calculate Stacking Height for Roman Shades

Green Roman shades drawn up.
Heavy decorative fabric that blocks sunlight is often used for Roman shades (Image: Curtains by Joanne Flickr Creative Commons)

Roman shades (sometimes called Roman blinds) are one of the most stylish and regal window treatments you can use to adorn your windows. Usually made of thick, elegant material, a Roman shade lays perfectly flat when in the closed position, but then folds back behind itself in neat segments as the shade is raised. Unlike shades that are designed to allow some sunlight to pass through them, Roman shades often use dense fabric with the aim of blocking out all sunlight.

Tip

There’s more than one way to hang your Roman Shades. With an inside mount, shades hang inside the window casing, creating a beautiful, clean look. An outside mount covers the entire window frame, including the trim, providing more light control and privacy than an inside mount. It’s important to decide how you want to hang your shades before you buy them so you can accurately measure your window for a precise fit.

While most window shades are designed to open up as far as possible in order to let in the maximum amount of light, the decorative appeal of a Roman shade means that it is often designed and installed so that some amount of the fabric remains exposed at the top, blocking out of part of the window. The measurement of this amount of fabric visible at the top when the shade is drawn up is known as the stackage, or stacking height. When you order a commercial Roman shade, the manufacturer will specify the stacking height in inches. Normally it ranges from 7 to 10 inches, but with very tall windows, the stack height may increase by another inch or so, due to the fact that there are more folds in the shade at the bottom.

Stack height is determined mostly by the width of the segments in the shade. Because each segment folds in half as it is drawn up behind as the shade is opened, the overall stacking height is generally about half the measurement of an individual segment.

When buying from a manufacturer, the stacking height of the shade will already be set according to the factory design, but if you are making your own Roman shade, you have some options for sewing them to create the stacking height you want. This means that if you want a wider stacking height, you should sew your blinds with fairly wide segments. This might be your choice if you have truly wonderful fabric you want to make sure gets displayed, or if the window is very tall and you want to balance the proportions by making sure a good amount of fabric is always visible. On the other hand, creating your shade with narrower segments will mean a smaller stacking height, which might be the best choice where you want the option of letting in as much light as possible through the window.

Let's discuss how you can calculate Roman shades to understand and obtain the stacking height you want.

Things You'll Need

  • Tape measure

  • Calculator

Step 1

The first step involves taking measurements of the window itself and determining the desired length and width of the Roman shade you will be making.

  1. Determine the desired mounting location for your Roman shades: inside the window frame, or on outside the window case moldings. In most homes, Roman shades are usually mounted inside the window frame. But mounting them on the outside of the window frame, so they overlap the case moldings, allows several more inches of glass to remain exposed when the shade is pulled up into the open position.
  2. Make a mark on the top case molding or on the inside of the window frame to indicate where you want the top of the shade to be mounted.
  3. Now make a mark where the bottom of the shade will fall. On outside mounted shades, the bottom of the shade may overlap the bottom case molding. But if the shade is mounted inside the window frame, the bottom of the shade usually just touches the bottom of the window opening.
  4. Measure the vertical distance between the top mark and the bottom mark. This will be the overall length of your Roman shade. Take a note of this measurement.
  5. Measure the desired width of your shade. If the shades will be mounted inside the window frame, this measurement will simply be the horizontal distance between the sides of the window frame. If you'll be mounting the Roman shade on the outside of the frame, you have some options. The shade width could either cover the entire case molding, or it can be sized to cover only a portion of the moldings.
  6. Make a note of this width measurement.

With these two dimensions, you now have the overall length and width of the Roman shade, which you'll use when you make the shade.

Step 2

The next part is somewhat tricky, as it involves math and perhaps some trial and error to determine how wide the individual segments in the shade need to be in order to produce the stack height you desire.

Roman shades are generally designed so the fabric is divided into segments by horizontal rods or dowels that are used to lift the fabric up as the shade is raised. The stack height, then, will be roughly one-half the measurement of individual full segments (remember that the segments will fold in half as the shade pulls up). At the bottom of the shade, below the last rod, the last segment will be only one-half of a full segment. This allows the bottom of the shade to hang flush with the other folded segments as the shade is drawn up.

The challenge, then, is to take the overall height of the shade and divide it into a number of full segments and a half bottom segment, so that the stacking height you want is achieved.

The best way to demonstrate this is with an example. Let's suppose you're making a 60-inch tall shade, and you are making it with a luxurious fabric where you want a full 12 inches of stacking height visible when the shade is fully open.

  1. First, subtract the desired stacking height from the total. In our example, subtracting 12 inches from 60 inches leaves you with 48 inches. This remaining 48 inches will be the section of the shade that needs to be covered by full segments.
  2. Next, DOUBLE the desired stacking height. In our example, doubling the 12-inch stack height gives you 24 inches.
  3. Now, divide the number obtained in step 1 by the number obtained in step 2. In our example, 48 divided by 24 produces 2. This is the number of full segments, each 24 inches wide, your shade will require in order to produce a stacking height of 12 inches. In practice, this means that the shade will have one rod placed 12 inches from the bottom of the shade for the partial bottom segment, the next one 24 inches above that, and a third rod 24 inches above that.

Such calculations are easy when the measurements are easily divisible numbers, but they can get trickier with odd-sized windows, or if you have an unusual stack height in mind. In these cases, it will take a little trial and error to get it perfect. And you may need to compromise a little. It is fine, for example, for the partial bottom segment of the shade to be slightly wider or narrower than a perfect one-half segment.

With these measurements in hand, you're now ready to make your own DIY Roman shade.

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