A Rectangular Constructed Underdress

I love seeing other’s steps in making something, being self taught and always looking for better ways to do something. I thought this rectangular constructed dress would be a good one to start with!

What is Rectangular Construction? Essentially it is a method of construction use pieces that are all cut out as rectangles or triangles, etc. The idea is that in the past, fabric would have been expensive, so this method allows for the best use of the fabric with very little wasted! At first you may think, but how can this create something that fits well, we are not made of straight lines and edges? Give it a try, you will be surprised at how well it can fit even someone like me with plenty of curves!

Instructions and Steps:

This pattern and method can be used to make both dresses and tunics. Below is a summary diagram of the pieces cut, layout and assembly. I will go through each of these in greater detail below, with pictures of my steps.

Rectangular Layout_New


Using actual measurements vs. trying to fit a commercial pattern makes all the difference in the world for clothing looking and fitting right! Once you get the hang of it, you’ll never go back to commercial patterns. Rectangular construction is a good place to start because you need very little measurements.

  • Body piece: This will be the largest piece. It can be done with a fold at the shoulder or with a shoulder seam, depending on how much fabric you have. Either way you will need a front and back panel, cutting out one rectangle folded in half or two rectangles. You will need to measure the largest part of your body (b) divided by 2, and shoulder to hem (c). Add some fabric for seam allowance, ease, and hem adjustment. This may give a shoulder seam that is off the shoulder, depending on the person.
    • Option: Mock Set-in Sleeves-This is a good method if you have an area like bust that is wider in measurement than your shoulder width. This allows for you to have the arms-eye seam at your shoulder point, while still keeping it as full as you need farther down. To do this, trim off the top corners of the body pieces. This will be an angle from the shoulder measurement (a) out to the widest part (b), and down to where the top of the gore will be, usually natural waist.
  • Sleeves: Measure around a flexed bicep/widest part of the arm (d) and add some ease for movement. You will cut out two rectangles that will be folded in half lengthwise. For the length, measure from shoulder point to where you want the cuff to be (i).
  • Gussets: Gussets allow for a diagonal piece of fabric at the stress point under the arm. They can be skipped, but they will help with fit and seams from pulling apart. If you are using very wide sleeves, you probably don’t need them. Most are 5″x 5″ squares. For myself I find I get a better fit using 6″ x 6″ diamonds. (h)
  • Gores: The gore will add flare to the garment, since usually the rectangle body piece is not wide enough for the hem. So think about how wide you want your hem to be, subtract what you have already from the body pieces and divide what is left by 4. This will be the width of the gore (f). For the length of the gore, take your sleeve measurement + your gusset measurement, this will be as long as you need (e). They can be shorter, it depends on if your body piece can be sewn together on the side and where you want the flare to start. Since I wanted mine to start lower at my natural waist, I have a side seam between my gusset and top of my gore (see first picture). There are many option with gores and I plan on writing another post on this topic alone.

Layout and Cutting:

The layout of the pieces will depend on your hem length and body width. but you should be able to arrange pieces to get the maximum out of your fabric with some to spare. If you’re short like me, the width of the fabric can be enough for the length of your body piece.

  • Cutting straight lines: If you are working with linen, you can pull a thread to create a straight line to follow while cutting. Another method is to tear the fabric instead of cutting it. Make sure if you get your fabric cut at the fabric store, you will need to straighten that cut edge most likely.
  • Trimming the bottom of gores: Another step to take is to trim the bottom of the gores, so that the bias/diagonal side is the same length as the straight side. If you don’t do this, you can end up with strange points at the hem even if everything seems to match up. An easy way to do this is to take a measuring tape, pin it to the top and swing it over, marking the length of the straight side:





  • Cutting the neckline: The key to this is start small, and keep close to the sides of the neck. Remember it will be larger by the seam allowance all around. thin about if it will be open at all in the front, then it can be even smaller. Start with a couple inches in the back and maybe 3″ in the front. You can also play around with measuring tape to get an idea, but think offset oval, not a half circle.
  • Trimming the sleeves: If you’d like a tighter fitting cuff, now is the time to trim the sleeve edges lengthwise, narrowing to the cuff width you’d like.

Putting it Together: I use 0.5″ seam allowance, usually sewing the seams on the machine and then hand finishing the seams. Whenever you are joining pieces like setting in the gusset or gore, all you need to do is stop the seam one seam-allowance width before the edge. Then when sewing pieces together, they line up flush with each other.

  1. Gusset to sleeve





2. Sleeve length seam

3. Arms-eye or Sleeve&Gusset to body





4. Gore to body: Start at the top. It is key to sew straight-straight and bias-straight, never bias to bias (the seam will sag from stretching eventually). First sew two gores together straight-straight, repeat with the other two. Then sew the bias to the straight edge of the body piece on either side.

5. Finishing neckline, cuffs, and hem:

  • For this project  I used a small facing for the neckline. Usually I simply roll the edge a 1/4″ or so, or you can make a binding using the same material.





  • One of the strongest seam finishes is Flat-Felled. If you are doing this seam finish, there is a proper order so that your gusset seams overlap each other nicely (see below). The order is: 1) top-back of gusset 2) top-front of gusset/sleeve length seam 3) bottom-front of gusset/arms-eye around to back/side seam.

Here is a copy of my class handout for constructing this type of gown or tunic: RectangularConstructedTunic.docx



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