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Construct a Japanese Torii Gate for Your Garden

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For some time, I had been thinking about building a Japanese torii gate for my garden. A torii gate marks the approach and entrance to a Shinto shrine. It is the division between the physical and spiritual worlds. Shinto is a native religion of Japan and was once its state religion. Probably the most famous torii is the one at Itsukushima Shrine located at Miyajima, near Hiroshima. Mine is a little more modest.
 
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Step 1: Torii Components

After a bit of poking around on Google, I found that all torii gates are made up of three horizontal components:

- Kasagi: The very top beam of a torii gate. These beams can be straight or curved.
- Shimagi: A second beam directly underneath the kasagi in more complex forms of torii gates. Their ends are either straight or cut with an inward slant and the overall shape of the beam is that of an upside down trapezoid.
- Nuki: The secondary beam of a torii gate. On more complex torii gates, it is held in place by kusabi (wedges). This beam is always straight.

The other components of a torii are the:
- Hashira: The supporting pillars of the torii gate
- Gakuzuka: A centre post that connects the Nuki & Shimagi (optional)
- Kusabi: A wedge used to hold the Nuki in place (optional)
The Shimagi is usually placed below the lintels at a distance about equal to the diameter of the pillars.

The dimensions that I ended up choosing for my torii are somewhat of a trade-off given the thickness of my Hashiras (poles).
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Wayne_san6 years ago
I completely understand the limitations of budget affecting choice of materials. For more classically Japanese proportions of a Torii gate, I recommend: The hashira be made to "lean in" slightly, approximately their own width. A plumb line dropped from the center of the nuki at the OUTside edge of the hashira should just touch the INside edge of the hashira at the ground. The hashira size (diameter) be 1/10 the measure of the opening. The distance between the inside edges of the hashira at the ground be equal to the height from the ground to the bottom of the nuki. The length of the nuki on each side, from the center of the hashira to the end of the nuki, be equal to 1/3 the length of the center portion of the nuki (between the hashira), from center to center on the hashira. The nuki height be equal to the hashira -- and the width should be 2/3 its height -- for example, 150 mm x 100 mm. With those proportions of the hashira and nuki, it will be necessary to make the nuki in 3 sections, 3/5 for the center section, and 1/5 for each of the end sections, plus enough additional length to cut tenons to fit into the mortise in each hashira. Side-by-side or over-and-under tenons will work equally well. The kusabi are absolutely indispensible for this type installation. I also recommend tenons at the top of the hashira, and corresponding mortise in the shimagi. I advocate building a torii gate without metal hardware. So, consider boring through the tenons once assembled and driving a wooden pin through the entire joint. Remember that the hashira will not be exactly perpendicular to the ground, if erected "leaning in" as I've described, so the mortise will need to be adjusted slightly so that it is still parallel to the ground. For a gate with both shimagi and kasagi, the shimagi height and width dimensions should equal the nuki diameter. The space between the shimagi and the nuki should be no less than the height of the nuki (the beam itself, not height above ground, obviously) and no greater than 1-2/3 the height of the nuki. For a gate with shimagi only, the shimagi width should be 10% more than the hashira, and its height should be 1-1/3 the size of the hashira. The ends of the shimagi should touch a line drawn from the outside edge of the hashira at the ground to the end of the nuki (and extended through the horizontal plane of the shimagi). The angles of the ends of the nuki and shimagi are found by cutting according to that same line just described. The length of the kasagi (and the angles of the end cuts for it) are found by drawing a line from the center of the gate at ground level to the outside edge of the nuki, and extending it through the horizontal plane of the kasagi. I have not been able to find the method for determining the curve of the kasagi. I recommend dividing the length into 5ths, with the center 5th level, the next two 5ths (left and right) sloping upward at a 5:1 pitch (that is, for every 5 units of length, elevate 1 unit) giving about an 11 degree angle, and the ends on a 3:2 pitch, giving about a 34 degree angle. Since my gate would be a bit heavier, I recommend no less than 1 mm below ground for every 3 mm above ground. 1 mm blow for every 2 mm above is even better. Dig the holes 35% deeper than needed. Fill that bottom, extra 35% with concrete 24-48 hours before setting the hashira in the ground. While that concrete "foot" is setting, consider standing the hashira in a 5 gallon bucket of water seal - for 24-48 hours. When pouring in the concrete around the hashira, have a mold at the top so that the concrete will rise 10 - 15 cm above ground level. These are all recommendations, made in part from what I have been able to gleen from a variety of resources, including living in Japan for four years. There is a written work, The Five Secret Books of the Master Carpenter, which gives the proportions of the length of the nuki, and the stipulation about the relationship of height and width of the opening that I described above. Although I've seen that reference quoted in English, I was never able to find a copy, not even in Japanese, much less a translation. Cheers.
p3-orion Wayne_san11 months ago
(removed by author or community request)
p3-orion p3-orion11 months ago
An excellent writeup; arigato for your research, Wayne_san. However, I believe you are mistaken in one detail, that being the angle of the vertical posts, the hashira.

You said that a plumb line should fall from the outside edge of the hashira (at the height of the lower horizontal bar, or nuki) to the inside edge of the hashira at ground level; that is, the hashira leans in by an amount equal to its diameter. However, in examining numerous photos of traditional Japanese torii, I find that the outer edge of the hashira (at nuki elevation) almost always lies exactly over the CENTER of its base; that is, it leans in by an amount equal to HALF its diameter. I think you will find that this angle is both more traditional and more visually pleasing, and may even be somewhat easier to construct.

Also, while I agree that when there is only one shimagi (upper horizontal bar) it should be one-third wider than the hashira, few larger torii HAVE only one shimagi; most also have the kasagi "roof" over the shimagi. In those cases, the shimagi's width is actually a bit less than that of the hashira. On the ones where I could tell, it appears to be the same width as the nuki, which would make it one-third SMALLER than the hashira diameter. The kasagi on top is wider than either, and I suspect is at least one-third larger than the hashira (as with the single-shimagi torii you mentioned.) However, on torii that have a kasagi which is actually a pitched roof (like the famous one at Itsukushima shrine near Hiroshima) it looks like the kasagi may be substantially wider than that, perhaps as much as 2-3 hashira diameters.
Wayne_san p3-orion11 months ago
Thanks for the feedback. When I have an opportunity, I'll factor those changes into a new Sketchup drawing to get a sense of how it changes.

I think there are subtle differences by region, period, and craftsman. I can't locate my original notes, but I recall the lean-in being calculated both ways in the gates and references I examined. The kasagi length seemed to be dependent on a line from the base of the hashira to the ends of the shimagi then extended to the ends of the kasagi.

There's software on the market that would enable me to make precise measurement from photos, but I don't own any of it. If I get back to Japan in this life, I'll keep a notebook, pencil, digital camera, shot line, plumb, and tape measure with me. A step ladder might pose a problem on the trains, but I'll need that, too.

Thanks again.
Wow, your instructions are excellent. Thank you!
BlueRock (author)  Wayne_san6 years ago
Wayne San, thanks for your comprehensive comments concerning the classical ratios of a Torii.
Wow!
pedro1471 year ago
どうもありがとう, Dōmo arigatō Bluerock. May your garden be scented with the perfume of 1000 Japanese maidens
simpatico2 years ago
I'm interested in building a downsized Torii gate of timber bamboo. Any thoughts on the durability of the bamboo in the ground, using concrete "feet" or not, gravel?
BlueRock (author)  simpatico2 years ago
A bamboo Torri would sure look interesting. I'm not sure on the durability of bamboo though. I've a bamboo screen inset to gate and the bamboo has cracked lengthwise. However, this maybe a result of it coming from a humid environment and seasoning in a dry climate where I live. Based on Arkie's and ejsilver26's comments below, you maybe best advised to go straight in the ground.
arkie4 years ago
Nice work. Well balanced design. You mentioned (Feb '07) that the concrete had cracked. Would it be possible, considering your climate, to use the material that you excavated for the hole as back-fill? Coupla' shovels at a time and tamp down with an iron bar or wooden post?

An old hillbilly watched me trying to erect posts for a barn. When I started mixing concrete, he asked if the wet slop was going to contact wood. I said yes. He asked if I thought the wood would absorb any moisture and swell. I said yes, I guess so. He asked if the wood and concrete would eventually dry. I said yes.

Then he asked, "When the wood dries, and shrinks, won't that leave a gap between the dry wood and the cured concrete? Won't any rain trickle into that gap and soak your post all the way to the bottom? Don't ya' think that wet wood will encourage mold and bugs and rot?"

He went away. I stopped using concrete.
Awesome explanation. I've always been told to ensure that wood doesn't touch concrete, but that is best reason WHY that I have heard. I've been told that they will rot, but not why they will rot. It makes perfect sense.

I'm assuming that treated wood might not be as big of an issue, since it can be treated to resist absorbing wood and rotting. Any thoughts?

EJS
I don't want to 'highjack' the thread of BlueRock's excellent Japanese torii, so this will be (moderately) brief.

Totally submerged wood, treated or not, can stay in prime condition for centuries. New Zealand's kauri wood is workable after 45,000 years buried in the wet, boggy ground. Logs from the Louisiana swamps and the American Great Lakes are being recovered and used after centuries underwater. They stayed wet.

Log buildings in Europe have been gathered in outdoor museums and are open to the public. With 4-foot eaves to protect the wood from rain and snow, and stone sills to keep them from ground contact, the buildings are in good shape after 500-600 years. They stayed dry.

The interface between dry and wet is where the damage occurs. I removed a fence for a friend in the Arkansas Ozarks. The posts were made of aromatic Western red cedar... the same long-lasting wood used in cedar chests. The above ground portions of the posts were weathered but strong and intact. As I dug, and wiggled the posts, they snapped off at the rotted areas at ground level; however, digging for the buried portions revealed solid timbers. No evident aging or damage to the underground wood.

The treated lumber available at the limber yard or 'big-box' hardware store normally has a rating (in years) and a notice that it is intended for non-ground contact. Ground-contact rated wood is available, but the price goes up. There is a marine-grade treated lumber which is VERY expensive, but survives the wet-dry cycle for years.

I hope this helps... and my apologies to BlueRock for my wordy reply.
BlueRock (author)  arkie2 years ago
Thanks Arkie, interesting information.
Roger4084 years ago
It may depend on your climate, but here in northern California, we need to put 6 inches of gravel in the bottom of a post hole, then add the concrete around the poles to anchor them.  That allows the moisture that gets into the wood to drain away and posts last much longer.  Redwood fence posts done that way last up to 50 years, fully encased in concrete you're lucky to get 10 years before the part in the ground rots away. 

BTW what is the species you call oregon?  Could it be douglas fir? Around here Oregon is  a piece of geography, that little bit of a state just north of us ;-).
BlueRock (author)  Roger4082 years ago
Yes, suppliers here tend to use oregon and douglas fir interchangably.
Thanks for that excellent tip Roger, I didn't understand the science behind the post-to-gravel method though I've seen it done that way.
Looks great!  Would it be total sacrilege to use PVC pipes for the uprights?  No more problems with rotten wood. 
BlueRock (author)  Culturedropout2 years ago
Yes, you could use PVC packed with something like soil or gravel to give it rigidity. Thanks for the suggestion.
THYMETOCHAT4 years ago
Beautifully done!   What an entrance into your garden!  What is the color you used called?  It's PERFECT!  Thanks for sharing.  Great instructable.
BlueRock (author)  THYMETOCHAT2 years ago
Thanks, the colour is vermillion but is probably called something else in your neck of the woods.
tinker2343 years ago
wow love it
Wonderful!
Be Blessed this Torii!
 an interesting bit of trivia: it is believed that if you throw a coin and it lands on the top of a torii gate you get instant acceptance into heaven, However! if you miss the top or it falls of you go to hell, there are no second chances and make note that if you knock off somebody else's coin they get sent to hell.
REA4 years ago
for those curious, this is a myouji torii style.  for more styles click here.
Jahleim5 years ago
Is it possible to download this.... It is by far the best and most informative instructions,And Iam doubting I will find anything remotely as informative and so easy to follow. Thanks to the uploader.
BlueRock (author)  Jahleim5 years ago
Click on the PDF icon near the top of the page and you can download the entire instructable in PDF format. Otherwise, move the mouse pointer over the components image, right click with the mouse and select option and save the picture onto your harddrive.
Thanks BlueRock. Got the download but had to save target and coy the instructions page by page,painstaking but worth it Thanks.
Dvickery5 years ago
I am unfamiliar with the terms Copper Logs and Oregon wood. I assume copper logs may refer to what we call pressure treated (cupric arsenide). Oregon wood I have no idea of.
BlueRock (author)  Dvickery5 years ago
Yes, Coppers Logs are pressure treated timber that resists pests and has a degree of rot resistance when buried in the ground. Oregon (also known as Douglas Fir) is a softwood.
D.L.H.5 years ago
This is well written and instructed good job on it.
Patented6 years ago
Why did you put this instructables in the skewer gun group?
altomic6 years ago
looking at your backyard I'd say you live in Melbourne. either doncaster or or towards st albans. anywho torii gates have differing dimensions depending on the area of Japan. Just like tatami have different sizes of Jo very cool instructable by the way. and great gate.
Cool! Great Instructable! Very Interesting! Thanks Joe
Margot7 years ago
I lived in Japan and was using this to make a smaller scale model for my home garden. I have it nearly finished but I necessarily had to change dimensions. Why? Because your dimensions have errors (?). E.g., Space between Nuki and Shimagi shown as: 180mm. Dimensions for Gakuzuka shown as: 220mm X 130mm X 60mm. In no way would the Gakuzuka accurately fit into the space between the Nuki and the Shimagi. In proportioning for my small torii, I had some difficulty with other dimensions. This is meant to be constructive. The pictured torii is excellent but the given dimensions do not work. If I am wrong, please tell me. Perhaps there are others seeking to construct a torii, scaled down or up; they may be having difficulty. I really like the site! Margot
BlueRock (author)  Margot7 years ago
Margot

Thanks for the comments.

The space between Nuki and Shimagi is 180mm. The Gakuzuka has 20mm tenon joints on either end, therefore, the cut length of the Gakuzuka needs to be 220mm - i.e 180+20+20=220.

You may have had problems with the hashira dimension because its cut length is actually 3000mm, rather than the incorrect 3600mm shown in the diagram above (it butt joins to the shimagi). Sorry about that.

The kasagi dimension is another thing altogether. Due to its upturned ends (30mm), you would need to begin with a piece of timber 2700x160x30. Then 30mm, tapering down to 0mm at the ends, is cut off what will become the top edge of the kasagi. Sorry for the awkward description.
ryden BlueRock7 years ago
Instead of cutting a strip from the topside, what you should do is mark the curvature on the bottom edge and carefully cut of the lower corners. These corners are then attached to the top. Much less work and no spillage. This is how i make S-shaped gate tops.
Margot ryden7 years ago
ryden, Thanks for the comment; I had done just that and my torii looks fine. It is painted and ready for installation and celebratiion. Margot
BlueRock (author)  BlueRock7 years ago
P.S. The picture in step 4 shows the tenon joints fairly clearly. In reality, the dimensions are not that critical, whatever is pleasing to your eye is good. Even when correctly interpreted, my dimensions are not what one would consider classical in proportion. They are a tradeoff based on price and availabilty of materials. In ideal world, I would have used much thicker timbers all round, but the price would have blown my budget for this progect.
Bozz8 years ago
You did a great job.
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