DIY Costco Under Quilt | Instructions & Overview

**mrmotorcycle** · 07-03-2020, 11:30

Hey all,

I recently repurposed a Costco Double Black Diamond down throw as an Under Quilt (UQ). Wanted to share some thoughts and findings from my experience with those that have done it and those that are looking to take this on as a project. I used this guide from Serac as a template. It's a great step-by-step. I also took a few liberties adding more down to each channel after seam ripping. I wasn't getting the loft I wanted and decided to add more down to reduce the likelihood of cold spots and give myself better odds of stretching this quilt to a 3-season option.

Before moving forward with the Costco down throw, I also looked into sewing an UQ from scratch. There are a ton of great guides out there, but I eventually went the Costco route for two reasons. 1) Supplies from scratch were coming in at ~$150 (down is expensive) and 2) I'm a novice with a sewing machine (but getting better!). I know there are cheaper synthetic fill options, but I want to keep things light as possible and am not as concerned about getting the down wet. I'm usually under a rainfly or have one close by in my pack. I intend to do another quilt in the future from scratch with proper baffling, but will save it for another day. When I do, I'm planning to work from this guide from Instructables and this YouTube tutorial.

Overall, I'm really content with how this UQ turned out. It was time well spent during COVID-19 lockdowns/quarantine and I can't communicate how much nicer this set up is for sleeping than using an inflatable pad for bottom insulation. No more shifting and tossing to keep a pad underneath me through the night. This UQ is definitely more of a 3/4 length set up. If you're unsure about length, lie down next to a tape measure to get a feel for how this would fit you. I'm 5' 10" and it's just right, but I'll still need to sleep with a pillow and some socks. This quilt may be a little short for taller folks in cooler temps.

Temp Rating. I have no idea. It's difficult to calculate loft because the channels are sewn through, but I'm planning for this to be a trial and error process to discover where temp bottoms out. I'm expecting to end up somewhere near the 40F mark.

Supplies. I ordered all materials from Amazon, but you can probably find everything at a craft store. Amazon was the easier option while in lockdown/quarantine from the pandemic.

For more research, I recommend checking out this post from @xollox. They compiled a ton of DIY guides on here - it's a really handy collection of resources.

UQ Dimensions

Starting: 70"x 60"
Ending: 50" x 60"

Step by Step

Seam Rip all the 60" seams (excluding the ends of the throw). You'll have to do this 13 times. It's time consuming and a rote task, so you might want hit play on an audiobook/tv show/etc. to pass the time. While seam ripping, play around with where you cut the seam and where you pull from. Testing out tactics with this throughout this step will pay dividends in efficiency, and you'll be able to remove longer lengths of thread more often.
Shake out the throw and shift all the down to one end of the channels.
Cut across from the emptier side of channel to add more down. Do this step outside if you can. It's a mess. I was able to get my hand and arm in the channel to push down a far as possible so that it wouldn't blow out as I moved across each channel. If you can't fit your hand/arm, you might be able to use a cooking spoon, etc. to push the down further into the channel.
Use packaging tape to temporarily close channels. The down will go everywhere and tape helps a ton while prepping to close the channels again in the next step.
Sew across the quilt to close the channels, taking it in ~20" (4 squares).
Cut off the excess nylon
Sew on your grosgrain channels. I used 1.5" grosgrain. I don't recommend going any narrower than 1.5". It allows for just the right amount of space for 1/8" shock cord.
Thread shock cord. Using a wire hanger to thread shock cord made this process a lot easier. I would thread the hanger through so that the hanger is exposed on both ends, then tape shock cord to the end and pull it back through the entire channel.
Add cord locks. Play around with how you set up this up. There are a lot of ways to get everything clipped in and suspended, so you'll just need to find what works for you.

General Takeaways

Loft on this style of quilt (sewn through) wills always going to be less superior to baffling. Channels that are sewn through will be oblong and prevent down from achieving max loft. Overstuffing channels can improve the warmth capability of this UQ.
For quick measurements, each square on these throws is 5" x 5"
Masking tape is a HUGE help when marking measurements, cuts, and progress on the nylon. Definitely good to have on hand.
Take the time with the seam ripping. It's tedious, but easy to make a mistake and dig into the nylon, especially when pulling out back stitching. Having a few patches or packaging tape on hand doesn't hurt in case this happens.
Wear a headlamp for seam ripping. Direct and bright light will save your eyes.
When seam ripping, use an overturned box or crate to work with the quilt while in your lap. It's easier to pull the material taught and get underneath seams.
After cutting any nylon or grosgrain, run it over an open flame to prevent any fraying. It's helpful to have a candle going when you're going to be cutting material.
Go slow while stitching the grosgrain. It's easy to hit the topstitching and miss underneath so only one side of the channel is secured. I ran a clothes iron over the grosgrain to create a crease. It helped, but only a little. I didn't find a substitute for careful and slow sewing when creating the channels.