Mending Hole in Crotch

A friend asked me if I could mend her holey jeans.  Made of stretch denim, they had worn through in the crotch.  This is unsurprising, since there's a lot of strain in a small area in the crotch of jeans.  Seeing that the fabric was thinning around the hole as well as at the point of damage, I decided to replace the whole crotch with a gusset.

In sewing, a gusset is the opposite of a dart: a dart shapes fabric by removing some; a gusset shapes fabric by adding some.  Gussets can be found in interesting places, like armpits and crotches.  In the early days of bras, before molded foam, the cups were made with gussets.  Corsets sometimes have hip gussets.  Basically, if the fabric is too tight and you slash it, that's a slit; fill the slit with fabric, and it's a gusset.  In this case, I decided to patch the hole, then cut away the original fabric, turning the patch into a gusset. 

HOW TO:
FIXING A HOLEY CROTCH WITH A GUSSET

STEP 1: MEASURING THE AREA
Here I use red pins to mark the far edges of the damaged area, making sure the fabric there is strong enough to hold a patch.  The area to be mended is larger toward the back.

Since this is stretch denim but my patch is not, I pull it taut when taking key measurements. 

STEP 2: A PATCH TEMPLATE
So my cardstock template ends up being larger than the fabric when it's relaxed, but hopefully the size of the fabric when it's worn. 

STEP 3: PREPARING THE PATCH
I lay the template on top of my scrap denim and iron the seam allowances up and over, creating the shape I want.  This is why I use cardstock instead of flimsy paper-- a paper template wouldn't hold up to the bending of the fabric or the steam of the iron. 

Here's the patch laid on top of the crotch of the jeans. 

STEP 4: PINNING THE PATCH
Using the original pin markers to guide me, I pin the patch onto the crotch.  Remember that in this project the patch is larger than the area I'm patching, because the patch isn't stretchy and the original is. 

STEP 5: SEWING THE PATCH
Here I'm sewing the patch on, with the right side of the garment up so I can see what I'm doing.  The seam is top-stitched just at the edge of the patch. 

As I sew, I pull the stretchy fabric to match the non-stretchy fabric in length. 

Here's the completed first seam!  See the puckering in the middle?  That's the stretchy fabric underneath pulling.  I fix that in the next step. 

STEP 6: CUTTING THE ORIGINAL
I cut the holey fabric away, leaving some seam allowance, and making sure not to cut the new patch at all.

STEP 7: FINISHING EDGES
I hand-stitch this part because I can't get my machines into the corners at all.  I use blanket stitch to bind up the raw edges, and to hold the seam allowances from the patch together with the seam allowances of the original. 

STEP 8: TOP-STITCHING
I then top-stitch again, from the right side, using this second line of stitching to hold the seam allowances down and to match the styling of the jeans. 

Notice the puckering is gone now that I've cut the holey fabric away? 

Here's an interior view of the gusset. 

Structurally, one benefit of the crotch gusset is that instead of one intersection with four seams coming together, there are four intersections with three seams each.  This distributes the strain of wear and tear over a wider area. 

I bury my thread ends, and I'm done.  I ask my friend to try the pants on, and they fit fine!  The gusset is entirely concealed when she wears the pants.