Window Treatment DIY | Flat Roman Shade Tutorial

Do you have an area in your home that needs some functional and pretty window treatments? I’d like to offer an outside mount, flat Roman shade for your consideration. Our living room and dining room were in bad need of some protection from the evening sun (see my planning and thoughts on why I made these in this post and the before and after here). Today I thought I’d share how I made these flat Roman shades. Warning: this is a long step-by-step post! If you’d like to make a fully functional, outside mount, flat Roman shade, read on!

Disclosure: Some of the links below are affiliate links which just means if you purchase from the links provided, I may get a small commission at no additional cost to you! At Flawed yet Functional, I only reference products that have real value that I actually use.

Supplies

• Sewing machine
• All purpose pressure foot
• Blend hem stitch pressure foot
• Decorators fabric 54″ width – length of window + 7″ + 7% for shrinkage
• Drapery Lining or Blackout Lining – length of window + 3″
• Thread to match fabric
• Iron & ironing board
• Tape measure
• Extra long straight pins
• Scissors or rotary cutting tool
• Rings for Roman shades
• Cord lock
• Shade cord
• Dowel rod – width of window
• 1×3″ board – width of window
• Cordless drill
• Stapler (manual or pneumatic)
• Screw eyes

Measure the Window

The first step is always to measure the window accurately. You need to know two things before you measure: (1) inside or outside mount and (2) style of Roman shade desired. This tutorial is for an outside mount, flat Roman shade.

Measure the width of the window, from outside trim to side outside trim, at the top, middle, and bottom of the window. Take the widest measurement and add 1/4″. This is the finished width.

Example: The widest measurement was 39 3/4″ for my window so my finished width was 39 3/4″ + 1/4″ = 40″. I chose to make my shade just as wide as the window casing. Feel free to add more width if you want the casing covered more.

Measure the height of the window, from the top outside trim to the sill, at the far left, middle, and far right of the window. Take the longest measurement and add any additional height to mount above the window. This is the finished height.

Example: The longest measurement for my window was 65 1/2″ and I wanted the shade mounted 6 1/2″ above the window so my finished length was 65 1/2″ + 6 1/2″ = 72″.

Calculate Cut Lengths

The cut length and width for the face fabric and the lining will be different. I recommend drawing each out on a piece of paper to avoid confusion.

Face Fabric

Cut length: Finished length + 4″ for hem + 3″ for mounting room

Example: My window is 65 1/2″ high, and I’m mounting it 6 1/2″ above the window. So for my shade I cut the face fabric 65 1/2″ + 6 1/2″ + 4″ + 3″ = 79″

Cut width: Finished width + 6″ for side hems

Example: My window is 40″ wide. So I cut my face fabric 40″ + 6″ = 46″ wide.

Lining

Cut length: Finished length + 3″ for mounting room

Example: My window is 65 1/2″ high, and I’m mounting it 6 1/2″ above the window. So for my shade I cut the lining fabric 65 1/2″ + 6 1/2″ + 3″ = 75″

Cut width:  Finished width

Example: My window is 40″ wide, so I cut the lining 40″ wide.

Iron Fabric and Lining

The fabric and lining should be as flat and smooth as possible before cutting. If possible, wash, dry, and iron the fabric to eliminate any shrinkage. The fabric I chose is dry clean only, so I ironed it and the lining then proceeded to cutting.

Cut Fabric and Lining

After ironing, lay the fabric out on a flat work surface. For me, that was my living room floor. My fabric had an obvious pattern repeat so I chose to center the roman shade on the pattern. This decision made cutting my fabric much harder, but I think the final result is more professional this way.

Quick side note: When making multiple shades for side-by-side windows, make sure to match the patterns. I laid the fabric for the second shade on the floor, right side down then laid my finished shade on top, right side down.

Then I carefully tweaked the position of the finished shade to match the pattern with the uncut fabric then I marked the top line of the shade. The sides and bottom will still need to be measured to allow for seam and hem allowance, but you can use the top line from the finished shade as your starting point.

Now back to measuring and drawing the rectangle for your shade!

Draw a Straight Line Parallel to the Selvage

Calculate how much excess to trim from the edges of the face fabric by subtracting the cut width from the width of the fabric. (Example: 54″ – 46″ = 8″) Divide the answer by two to get the amount of excess to trim off each side (Example: 8″ ÷ 2 = 4″). For my shade, I wanted to draw two lines 4″ from the selvage (the finished edge of the fabric).

Measure 4″ from the selvage and make a dot. Move down the fabric about 3 feet and make another dot 4″ from the selvage. Using a long straightedge or level, connect the dots to draw a straight line.

Move down the fabric another 3 feet or so, make another dot 4″ from the selvage. Using the second dot and this new, third dot, draw a straight line. Continue until you’ve made a line the cut length of your shade.

Repeat on the other side of the fabric.

Draw a Straight Line Perpendicular to the Selvage

Now you need to make the top and bottom lines to complete the rectangle shape of your shade. Begin with the top of the shade.

Using a T-square, line up one edge with the drawn line on one side of the fabric. Be very precise, make sure the entire edge of the T-square lines up with your drawn line. Make a hash mark/dot along the perpendicular side.

Repeat on the other side of the fabric.

Using the long straightedge/level, draw a straight line between the hash marks, making the top edge of the rectangle.

Draw a Straight Line for the Cut Length

With a straight top line, creating the bottom line for the final cut length should be fairly simple. Using a tape measure, measure the final cut length from the top line and make a dot. Move to the other side of the fabric, measure the final cut length and make another dot. Use the long straightedge/level to connect the dots, making a straight line to complete the rectangle.

Re-Measure the Length and Width Before Cutting

Have you heard the phrase, “measure twice, cut once?” Take it to heart when sewing! Double and triple check your measurements before cutting the shade out.

I usually check the width and length the same way I measured the window in the first step. Measure the width at the top, middle, and bottom. Then I measure the length at the left, middle, and right. If everything is the width and length you were aiming for, cut away! If not, go back to each of your drawn lines to look for the discrepancy.

Repeat for the lining fabric according to the cut length and widths already measured.

**Be very careful when switching to the lining. Double check your measurements to make sure you don’t cut out the lining the same size as the face fabric!**

Sew the Side Seams

With the face fabric lying right side up, line up the lining with right side down along the left side of the shade. The lining should be 6″ narrower and 4″ shorter than the face fabric. Leave the 4″ gap at the bottom of the shade (this room is for the hem), line up the tops and the left side (Note in my picture below the tops do not line up. I cut this lining too long. Too long is better than too short! I just trimmed the extra length after sewing the sides).

Pin and sew a 1.5″ seam along the left side.

Lay the shade back on the ground and line up the right sides and top. Since the lining is narrower than the face fabric, the fabric will bunch up. Don’t worry. It will all work out in the next step. Make sure there is a 4″ gap for the hem at the bottom of the shade.

Pin and sew a 1.5″ seam along the right side.

Turn the outside mount flat roman shade right side out so the right side of the lining and the face fabric are facing out. Lay the shade on the floor, smoothing out the seams and iron.

Hem the Shade

With the shade face fabric down, turn up the face fabric 1/2″ and press. Then turn up 3.5″ and press. Pin and sew the hem using a blind hem stitch.

I’ve heard that the method to do a blind hem stitch varies by sewing machine. I recommend looking up a video of your specific machine on YouTube.

The basics are this: put on the blind hem stitch pressure foot and select the appropriate blind hem stitch. Fold the hem under so that about 1/4″ of the face fabric is showing next to the lining. Then carefully sew along the folded edge.

The finished hem on the wrong side looks like this:

The finished hem on the right side of the shade should look like this:

Measure and Sew on Rings

Before making the grid to sew on the rings, calculate the spacing of your rings. I wanted my horizontal folds to be fairly thin, so I chose 6″ vertical spacing of my rows (6″-12″ is standard). I also didn’t want any sagging in between the rings, so I chose 9″ horizontal spacing (8″-10″ is standard).

Based on those measurements, I took the time to draw it all out to figure out how many rows of rings I would need. For this shade, I needed 10 rows with 5 rings each row for a total of 50 rings per shade. The measurements of my shade are charted out for reference in the figure below. Make sure to chart out yours with your specific measurements.

Lay the shade out on a flat work surface with the lining up.

Beginning at the edge of the hem, mark the position of the rings along the row. I placed the first and last rings 2″ from the edge of the fabric.

Then mark the placement of the remaining middle rings, spacing them evenly across the shade. The space between my middle three rings was just over 9″.

Next mark the rows for the remaining rings. My rows were 6″ apart. To do this, measure 6″ above the hem on the left and right side of the shade then use a straightedge or long level to draw a straight line between those marks. Add dots where each ring should go on each line.

Before sewing the rings on, I pinned one pin above each ring dot. I wanted to avoid any shifting of the fabric as I moved it to the sewing machine.

Then I used my sewing machine to tack each ring in place. This can be done by hand, but it is quick and easy with a sewing machine. Set the stitch to zigzag with the stitch length at 0 and stitch width wide enough to pass over the ring without nicking it.

The result is a clean, neat tack.

Repeat to attach all of the rings to the shade.

Insert Dowel Rod

Cut a 1/4″ dowel rod to the finished width of the shade minus 1/2″. The finished width of my shade was 40″ so I cut my dowel rod to 39 1/2″. Insert the rod into the pocket of the hem and sew the sides shut using a slip stitch.

Mark Finish Length and Finish Top Edge

Next lay the shade out, right side down. Measure from the bottom hem and mark the finished length across the top. Mark another line 2-3″ above the finished length line.

Trim the remaining fabric at the top line. Finish the top edge with a zigzag stitch.

Cut and Cover Mounting Board

Cut a 1″x3″ board to the finished width of the shade. Cover the board in matching fabric, being careful to match patterns so the edges look seamless.

For a flat mount, add screw eyes along the narrow edge of the board, lining up with each cord/vertical ring column. Mount the cord lock on the right side of the board with the brass roller to the outside edge (you can install it the other way, but you’ll be confused each time you try to lock/unlock the shade…ask me how I know…).

Be sure to have a screw eye for the cord closest to the cord lock. Do not just thread the cord into the cord lock. It will fray quickly with the friction caused by the weight of the shade (again, ask me how I know…).

Pre-Mount the Board

Hang the board with two long screws and drywall anchors. To accomplish this, drill the two screws into the board so they protrude 1/2″ or so out the back of the board. The screws were placed approximately 8″ from each end.

Mark the bottom line of the mounting board on the wall and use a level to line up the mounting board. Use the bottom of the mounting board because you likely won’t be able to see the stop of the board! Once the board is level and flush with the sides of the window trim, push the board into the wall a bit to mark where the drywall anchors should go.

Insert drywall anchors at the marked spots.

Attach Shade and Cords

Next staple the shade to the mounting board.

Now thread the cording through the shade. I somehow missed pictures of this step, but hopefully you can figure it out! There should be one cord for each vertical column of rings. Tie the cord securely to the bottom ring and feed the rest of the cord up through the rest of the rings, over through the screw eyes and through the cord lock.

Hang the Outside Mount Flat Roman Shade

The last step is to screw the shade into the drywall anchors.

Admire Your Finished Flat Roman Shade

You did it! Step back and admire your handiwork!

There are many steps to sewing an outside mount flat Roman shade, but none of them are terribly difficult. Take it one step at a time. You can do it!

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Want to remember this? Pin Flat Roman Shade Tutorial to your favorite Pinterest board!

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