How to Crochet the Thermal Half Double Crochet Stitch (Step-by-Step Photo & Video Tutorial)
The Thermal Half Double Crochet Stitch is a wonderfully thick and durable crochet stitch that creates a dense, insulated fabric perfect for projects that need extra warmth and structure. By working into both the front loop of the current row and the unworked loop from the previous row, this stitch creates a unique double-layer effect that looks beautiful and feels incredibly sturdy.
Whether you’re making potholders, bags, baskets, hot pads, or cozy accessories, the Thermal Half Double Crochet Stitch is a fantastic technique to add to your crochet skill set. In this tutorial, you’ll learn exactly how to crochet the Thermal Half Double Crochet Stitch with step-by-step written instructions, detailed photo tutorials, and a helpful video tutorial to guide you through every stitch.
First, check out my video tutorial on my You Tube Channel! Subscribe to get the latest crochet fun from Hope Corner Farm Crochet!
What is the Thermal Half Double Crochet Stitch?
The Thermal Half Double Crochet Stitch is a variation of the traditional half double crochet stitch that creates an extra-thick, dense fabric with excellent insulation and durability. Unlike a standard half double crochet, this stitch is worked through two loops at the same time: The front loop of the current row and the unused loop from the row below. This unique construction creates a double-layered fabric that is sturdy, squishy, and warm. Because of its thickness and strength, the Thermal Half Double Crochet Stitch is a popular choice for crochet projects such as potholders, hot pads, bags, baskets, mug cozies, and other items that benefit from added structure and heat resistance.
Materials Needed
Crochet hook of choice (I used a size J 6.0mm hook for this tutorial)
Yarn of choice (I used some size 4 medium weight yarn for this tutorial)
This crochet tutorial is written using US Crochet Terms
Crochet Terms Used
Half Double Crochet Stitch (HDC)
Helpful Tips for How to Crochet the Thermal Half Double Crochet Stitch
The first row of the Thermal Half Double Crochet stitch can feel a little awkward as you learn to work into both the back loop of the current stitch and the unused front loop from the row below. Take your time and keep your tension relaxed, as crocheting too tightly can make it difficult to insert your hook through both loops. It also helps to count your stitches at the end of each row to avoid accidentally adding or losing stitches. If you’re having trouble finding the front loops from the previous row, gently tilt your work toward you to make them easier to see.
The secret to the Thermal Half Double Crochet stitch is that every half double crochet is worked through two loops at the same time: The back loop of the current stitch and the unused front loop from the row directly below it. Working into both loops creates two interconnected layers of crochet, resulting in a fabric that is extra thick, durable, and nearly identical on both sides.
If you ever lose track of where to insert your hook, simply look for the back loop of the current row and the front loop left behind from the previous row, then work your half double crochet through both together. This technique is what gives the Thermal Half Double Crochet stitch its signature warmth, structure, and reversible appearance.
Multiples for the Thermal HDC Stitch
There are no multiples for this crochet stitch. Simply chain as many as you would like. Keep in mind that you will lose 1 stitch by working into the second chain from the crochet hook.
How to Start the Thermal Half Double Crochet Stitch
Begin by chaining whatever number of chains that you need for your crochet project.
Row 1 – Thermal HDC Stitch
Now we will begin by working into the 2nd chain from the crochet hook. Row 1 is a row of regular Half Double Crochet Stitches. I do work these HDCs into the chain in a specific way to get the bottom edge to have a nice rolled look to it. I will show you how I do that in the following steps.
First, to get the nicest bottom edge, I like to do the following. First, Yarn Over. When going to insert the crochet hook into the 2nd chain from the hook I like to insert it so that 2 of the 3 parts of the chain are on the top of my hook. This will leave 1 part of the chain on the bottom side of the hook. I have found that working into the chain in this manner gives a nice rolled edge to the bottom of my projects.
Now to complete the first Half Double Crochet stitch, Yarn Over again and pull through the chain stitch. There will be 3 loops of yarn on the hook at this point. Finally YO and pull through all 3 loops of yarn to complete the 1st stitch.
Now keep on working regular Half Double Crochet Stitches in the same manner across the chain.
Thermal HDC Row 2
We begin working actual Thermal Half Double Crochets in Row 2. A Thermal HDC is worked like a regular HDC, but with the addition of also working through the 1 leg of the chain that we didn’t work around. I like to call the additional loop that we work into the “Unused Partner Loop” from the previous row. Check out the picture below for a better idea of what loops we will be working into for this row:
Step 1 Row 2
Now begin Row 2 by chaining 1. We will slightly turn our work, but I hold my project a little differently to start.
Row 2 Step 2 How to Thermal Half Double Crochet
Next because it is a variation of the HDC, start by yarning over. First we will insert the hook to pick up the back loop of the 1st stitch (the last stitch we made in the previous row). Basically the Thermal HDC starts just like a Back Loop Half Double Crochet starts. There will be 3 loops of yarn on the crochet hook at the end of this step.
So in short, YO and insert the hook so you pick up the back loop only.
Step 3 Row 2
Now insert the crochet hook so that the hook picks up the “Unused Parallel Partner Loop” from the previous row. At this point there will be 4 loops of yarn on the crochet hook.
Row 2 Step 4 How to Crochet the Thermal HDC
Finally Yarn Over and pull through 2 of the loops of yarn on the hook. There will be 3 loops remaining on the hook at this point.
Remaining Row 2 Stitches
Repeat Steps 2-4 for the remaining stitches of the row.
Final Stitch of Row 2
Now it can be kind of difficult to see where to work the final stitch of the row. The final stitch follows the same steps to be worked, it is just being able to recognize where those loops are that we work into. So, to crochet the final Thermal HDC: YO, insert the hook to pick up the back loop, then move the hook across and insert it to pick up the Unused Parallel Partner Loop (4 loops of yarn on the hook now). YO, pull through 2 loops of yarn (3 loops remain at this point). Yarn Over again and pull through the remaining 3 loops. This completes the final stitch.
Row 3 How to Crochet the Thermal Half Double Crochet
Again the key for this row is recognizing where to work the Thermal HDC stitches. Check out the picture below for what loops to work into for this row.
Step 1 Row 3
Now start by Yarning Over and then picking up the back loop.
Row 3 Step 2 Thermal HDC
Next go across and pick up the Unused Parallel Partner Loop from the previous row. There will be 4 loops of yarn on the hook now.
Step 3 Row 3
Now Yarn Over and pull through 2 of the loops of yarn on the crochet hook. There will be 3 loops on the hook at the end of this step.
Row 3 Step 4 How to Thermal Half Double Crochet
Finally Yarn Over and pull through all of the remaining loops on the hook. This completes a Thermal Half Double Crochet Stitch. Keep repeating Steps 1-4 across the row.
Final Thermal Half Double Crochet Stitch of Row 3
Again the last stitch of the row can be tricky because the loops that the Thermal HDC is worked into sometimes are hard to see.
Additional Rows of Thermal Half Double Crochet Stitches
Finally the more rows of Thermal Half Double Crochets that you work, it becomes easier to see the loops that you need to work into. You will be able to hold your project in a more traditional manner as you get used to working these stitches. Below I have the same row shown being held in 2 different ways. Hopefully this helps with identifying the loops to work into for the remaining rows.
Finishing Row for the Thermal Half Double Crochet Stitch
Now to make the top of a crochet project using the Thermal HDC look more finished, I like to Slip Stitch the entire top of the stitch (not just the back loop) together with the Unused Parallel Partner Loop.
Finishing Row Step 1
Begin by inserting the crochet hook to pick up BOTH of the loops from the stitch (not just the back loop). NOTE: We DO NOT chain to start this row!
Step 2 Finishing Row for the Thermal Half Double Crochet Stitch
Now go across and insert the hook so that the Unused Parallel Partner Loop is picked up. There will be 4 loops on the hook at this point.
Finishing Row Step 3
Next Yarn Over and pull through ALL of the loops on the crochet hook. This completes one Slip Stitch to finish off the top of the crochet project using the Thermal Half Double Crochet Stitch.
Remaining Stitches for the Thermal HDC Finishing Row
Now continue repeating steps 1-3 for the remaining stitches across the row.
Final Finishing Thermal Half Double Crochet Stitch
Finally the last stitch again is trickier to see. It is worked in the same manner as the other finishing stitches for this row.
And that is the completed Thermal Half Double Crochet! Here is what the top looks like after a finishing row:
Here is what the bottom edge looks like:
Finished Thermal Half Double Crochet Stitch
How to Thermal Half Double Crochet Video Tutorials
Written Instructions Only
Start by chaining any number of chains. There is no multiple for this crochet stitch.
Row 1
Begin by working a regular Half Double Crochet into the SECOND chain from the crochet hook. Place 1 HDC in each chain across the row.
NOTE: I insert the hook so that 2 of the 3 parts of the chain are on the top of my crochet hook. This will give a nice rounded look to the bottom edge.
Row 2
Start by chaining 1 and turning your work.
Next start by yarning over and then inserting the hook into the first stitch picking up the BACK LOOP ONLY. (Note that the stitch has two loops at the top. Instead of inserting your hook under both loops, insert it through the back loop of the current stitch). There will be 3 loops of yarn on the hook now.
Now you will then insert the hook to pick up the unused front loop (I call it the Unused Parallel Partner Loop) from the chain directly beneath it. At this point there will be 4 loops of yarn on the crochet hook.
Next YO and pull through 2 loops of yarn. There will be 3 loops of yarn remaining on the hook at this point.
Finally YO and pull through the remaining 3 loops on the hook. This completes 1 Thermal Half Double Crochet Stitch.
Repeat this process across the row.
Row 3 and Beyond of the Thermal Half Double Crochet Stitch
Start by chaining 1 and turning your work.
Next start by yarning over and then inserting the hook into the first stitch picking up the BACK LOOP ONLY. (Note that the stitch has two loops at the top. Instead of inserting your hook under both loops, insert it through the back loop of the current stitch). There will be 3 loops of yarn on the hook now.
Now you will then insert the hook to pick up the unused front loop (I call it the Unused Parallel Partner Loop) from the pervious row directly beneath it. At this point there will be 4 loops of yarn on the crochet hook.
Next YO and pull through 2 loops of yarn. There will be 3 loops of yarn remaining on the hook at this point.
Finally YO and pull through the remaining 3 loops on the hook. This completes 1 Thermal Half Double Crochet Stitch.
Repeat this process across the row.
Finishing Row for the Thermal Half Double Crochet Stitch
Next start by inserting the hook into the first stitch picking up BOTH OF THE LOOPS FROM THE TOP OF THE STITCH. There will be 4 loops of yarn on the hook now.
Now you will then insert the hook to pick up the unused front loop (I call it the Unused Parallel Partner Loop) from the chain directly beneath it. At this point there will be 5 loops of yarn on the crochet hook.
Finally YO and pull through ALL of the loops on the hook. This completes a Slip Stitch to close the top of the project.
Repeat this process across the row.
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LOVE THIS CROCHET STITCH? CHECK OUT THESE OTHER CROCHET TUTORIALS!
Now that you’ve learned how to crochet the Thermal Half Double Crochet Stitch, you’re ready to add this wonderfully thick and durable stitch to all kinds of cozy crochet projects. Whether you’re making potholders, bags, baskets, or warm blankets, this stitch creates a beautiful fabric with incredible texture and structure. If you enjoyed learning this technique, be sure to explore some of my other crochet stitch tutorials, including the Thermal Single Crochet Stitch, Thermal Double Crochet Stitch, Half Double Crochet Stitch, and Deep Half Double Crochet Stitch. Each tutorial includes step-by-step instructions and helpful tips to build your crochet skills and expand your stitch library. Happy crocheting, and I can’t wait to see what you create next!