Couches have been a sore spot of conversation in our house for awhile now. After several frustrating moves and stressful roomate conficts, I ended up with a strage mixed matching of couches that probably belonged at the dump and didnt at all fit our space. I remedied our small livingroom seating through making a small storage couch, but we were left for a long time with our comfortable, but disgusting, large couch as our primary seating and only option for overnight guests. The couch went through many phases of its transformation. On a whim, when we arranged for other bulky items to be picked up as trash, we threw out the frame of our couch, hanging on only to the inner mattress from the pull out couch feature and all of the cushions. I pulled an old futon frame out of storage to be used to support the matress with the cushions placed on top. This was a comfortable solution and easy to cover with some fabric (a necessity to have washable covers with pets in the house) but the fabric would always quickly get tired and start falling out of place. There was a very simple solution: sew cushion covers. I FINALLY got around to doing it, and what a huge difference it has made!
To start, I simply measured the existing cushions to figure out the dimensions needed for the covers. There are 3 bottom and 3 back cushions, but I decided to make two long cases, rather than individual cushion covers. This was in part do to my laziness, but also I think helped with the comfort of the couch since the futon frame is longer than the cusions, the covers help keep the cushions tightly squished together and prevent you from wedging yourself into cushion crevices.
I didn't have enough pattered canvas to make the entirety of the covers, so I used a plain canvas drop cloth as a back to the covers. As a note: canvas drop cloths are a great tool for cheap, sturdy canvas fabric, but it does fray easily, so give yourself extra seam allowance. I decided to simply overlap the back pieces to allow the cushions to slip into, which in retrospect was the wrong choice. The overlap space was very tight to get the cushions into, and a zippered closure would have been a much better choice (though I wouldn't recommend using the dropcloth canvas with a zipper).
I have never sewn piping on a project before, but thought it would add a nice accent to the cushions and didn't seem too tough after I looked at a few tutorials for piping. I already had clothesline laying around and easily found extra fabric to use for the piping. According to all the tutorials I referenced, fabric for piping should be cut at a 45 degree angle as to allow for the best stretching around the piping/corners of the cushions. I cut 2" strips along the angle and stritched them together to make a long piece of fabric. I wrapped this around the clothesline as I went and stitched it (using a zipper foot so I could get nice and close to the clothesline) to the top pieces of the covers. In theory, this would have been nice to do to the backside as well, giving the cusions a more polished look, but i didn't have enough clothesline on hand and I was enjoying having this be a one-day project.
Originally I had thought I could sew the piping with a single seam, sandwiched between the top and side pieces, but all the tutorials I looked at for piping suggested sewing the piping first to one layer, and then adding the side pieces on after, with a second seam. Some even suggested sewing the piping first on its own, but that seemed really unnecessary. I did however go ahead and sew the piping to the front pieces before attaching the sides, thinking that perhaps it would be more difficult to sew close to the piping if it were sandwhich between layers.
After adding the side pieces, I added the canvas drop cloth pieces overlapping at the back (again, if I were to do this again, I would use a different technique, like a zipper) then flipped the covers right side out and stuffed them with the cusions. A few throw pillows and blankets startegically placed on the futon for maximum lounging comfort and VOILA a super comfortable seating option that fits much nicer in our space and provides a comfy place for our friends to crash.