I've had problems with certain tops bunching in the back, too. What's up with that?
Most bunching comes from your body shape being not related to the shape that the garment was cut for. Too much fabric in an area that doesn't have the:
- flesh to fill it out
- length to let it hang without bunching
Bunching fabric on tops
This is often created when someone has either a sway back, so the fabric can't fall straight over the derrière, instead it appears to bunch around the waist.
Or it can happen when you are very short waisted (or they cut the garment for someone who is very long waisted) and so there is too much fabric for the area that it was designed to cover.
You may be able to put darts in the garment at the back to get rid of the excess fabric, or possibly shorten the hem, depending on why the fabric is bunching.
Bunching fabric on bottoms
Trousers that end up with a bunch of fabric just underneath your bum is really common with flat bottomed girls. The rise is cut with too much fabric and we just don't have the curves to fill it out. This is very hard to fix in an already constructed garment, more possible if making from scratch. I find that apart from jeans, which I buy with a good level of stretch, I pretty much wear skirts and dresses so that the bunching issue is not a problem.
Would any of you sewers out there like to leave comments on how best to fix either/both of these bunching issues?