I wrote this article in 2010 and I’m giving it a face lift. We have been using our kotatsu table for over 10 years and we love it! There is nothing better than getting warmed up at the flick of a switch when it’s cold and rainy outside. It’s definitely my favorite winter appliance. It’s easy to build and it will pay for itself in just a few months. I highly recommend investing a little time and build one for yourself.
*Disclaimer: You should not leave any heating device unattended. We haven’t had any problem, but everyone needs to be safe and pay close attention to your heaters. We take no responsibility for and will not be liable for any thing you build.
It’s about this time of the year that all the personal finance magazines and blogs come out with articles on how to save money on heating. I will join the fray and reveal our secret to keeping our heating bill low AND staying warm. The usual advice to is to turn down the thermostat and bundle up. This is good for the wallet, but it doesn’t work for us because Mrs. RB40 hates being cold.
We live in a condo and the heating is done by electricity. Our monthly electric bill averages around $45 in the warmer months and about $75 in the winter. Our HVAC bit the dust a few years ago, but we haven’t fixed it yet. The system is so old, they don’t make parts for it anymore. So our winter heating is done by space heaters and our kotatsu table. I want to fix our HVAC, but it’s just easier to put it off. It will cost over $3,000 for a new system and we need to rearrange our bookcases (a huge job) to access the conduit. Someday, we’ll get it fixed, but we’ve been doing okay so it’s not a high priority.
The kotatsu table, in particular, gets a lot of use in the winter. It’s amazingly comfortable and we spend a ton of time around it. What is a kotatsu table exactly? A kotatsu table is basically a coffee table with two top surfaces, a heating element, and a big blanket to keep the heat in. I’m not sure where I first learned about the kotatsu table. I must have seen it in a Japanese comic or cartoon when I was a kid. The kotatsu table is very common there and every household has one. Most Japanese housing are not insulated well and the kotatsu table is an inexpensive way to stay warm.
You could buy a kotatsu table on eBay for $150-300, but that has a few drawbacks. Most kotatsu tables are shipped from Japan so it could take a while to get here. The expensive shipping cost probably rules this out for most of us. Another issue is that the kotatsu tables are generally pretty small. The usual table top size is 31×31 inches (80 cm) and most are only 14 inches high. We purchased our first kotatsu table at a Japanese store in Costa Mesa for about $130. That’s a great option if you have a local store that carries it. After a few years, I decided to build a bigger and taller table because we needed more table space. Our kotatsu table is a lot more comfortable now with the additional legroom.
Build your own kotatsu table
Here is how to make a kotatsu table. This is much more affordable than shipping one from Japan.
- $45 or $33 Coffee table – You need to find a coffee table with two top surfaces. A LACK Coffee table from IKEA is perfect for this. The bottom shelf can be easily moved to the top. You can get it in birch, white, or brown. The LACK is about 18” high and that’s just about perfect for us. There are two sizes
- $40 A 120 V to 100 V step-down voltage transformer – You can get this from Amazon. North America outlets put out 120 V but Japanese appliances run on 100 V. The heater element will run hot if you don’t use a step-down transformer. We don’t have a transformer and we only use the heater on the lowest setting.
- $60 to $100 heating element – You can buy one a “kotatsu heater” on eBay. They used to charge $30 shipping in 2011, but now there are many free shipping sellers. I tried other heating alternatives, but they don’t work that well for this purpose. A small space heater, for example, seems dangerous. The kotatsu heater element is designed specifically for this and it’s not that expensive now. I wouldn’t cheap out on this one. We also tried the “cozy legs.” It didn’t heat up enough for us.
- $0 old king size blanket/comforter – We have plenty of spare blankets so this didn’t cost us anything. I like the king size, but a queen would probably work too.
- $? pillows to sit on. You can pick up some big pillows from IKEA while you’re there. It’s a lot more comfortable than just sitting on the carpet.
- $10 Belkin power switch – I put the plug on a power switch. This made it much easier to turn on and off. I don’t have to plug it in every time I want to turn the unit on. Our heating element has a variable knob, but no off switch.
- $3 four-pack corner braces – You can get these from any hardware store.
Putting together the kotatsu table is really easy. You probably don’t even need instructions, but here they are anyway.
- Put the LACK coffee table together per IKEA’s instructions. Leave the lower shelf out for now.
- Mount the heater. I screwed our heating element right into the bottom of the coffee table. You probably can attach it with 4 corner braces from Home Depot as well. Or you can build a frame as pictured below. The mounting holes are on the side of the unit as you can see from the image.
- Throw the big blanket on top of the LACK coffee table.
- Put the bottom shelf on top of the blanket.
- Plug it in and you’ve got a kotatsu table!
If you can sit on the floor comfortably, a kotatsu table will be the best heating device that you ever had. We rarely turned on our forced air heater even when it was working. We spend a lot of time under the kotatsu table every winter and it saves us a lot of money on our heating bills. FYI, our climate is temperate and the concrete condo retains the heat well so our indoor temperature hovers around 64 degrees Fahrenheit. When we lived in a house, our gas bill would be over $150/month in the winter. Of course, it was a bigger space and had more exposure to the elements. I’m sure it will still work quite well in colder climate. Japan is very cold compare to Portland.
Happy building! How do you keep your heating bill down?
More on how to stay warm! – 10 Unconventional Ways to Save Money on the Heating Bill.
For 2018, Joe plans to diversify his passive income by investing in US heartland real estate through RealtyShares. He has 3 rental units in Portland and he believes the local market is getting overpriced.
Joe highly recommends Personal Capital for DIY investors. He logs on to Personal Capital almost daily to check his cash flow and net worth. They have many useful tools that will help every investor analyze their portfolio and plan for retirement.