Beams, Joists, and stuff
OK…your concrete piers are poured…in the right locations I hope, and your 6×6 pressure treated posts are in place and are plumb…right? RIIIGHT??!?!??!!!
They better be plumb…otherwise your yurt will probably fall down go “BOOM!”, or, at the very least look really really funny…
So, now let’s talk about minor details like framing out your actual platform…things like beams, joists, decking…little minor details like that which actually hold your yurt.
Note: At this point I fell down on the photojournalistic part of the job a bit, and didn’t document the framing as well as I had intended. If you look at the pictures I do have, and follow the text carefully, however, I think most of your questions will be answered. If not, use either the comment section at the end of this page, or the Contact JuicyMaters form to ask questions.
The shape of the framing is a decagon (10 sided geometric shape), but it is NOT symmetrical. All of the framing for the platform is of 2×8 white wood, with all wood below the beam/joist level being pressure treated, and the subfloor/decking being .75x 4×8 tongue and groove sheathing. All metal from the ground up through the subfloor level is galvanized…framing nails, decking nails, post L brackets, joist hangars…everything. Every contact point between the subfloor sheathing and the beams/joists, in addition to being nailed with ring shank galvanized nails, is glued using PL400 Subfloor and Deck Adhesive (don’t cheap out here and skip the glue…or do you actually WANT your floor to squeak?). The same thing applies to nailing the decking…nail every 8 inches along beams and joists or suffer with a squeaky floor. The nails for beam/joist framing should be 16 penny galvanized if hand drives or 3 inch galvanized D-heads if you rent a Paslode gas hammer. The decking nails are 8 penny galvanized ring shank hand drives, or 2 inch galvanized ring shank D-heads if using a Paslode.
A note about nailing: You will be driving a lot…a LOT…of nails if you frame and deck your platform right. Do yourself a favor and buy or rent a Paslode gas framing nailer. The rental at most Home Depot’s is $25/day, and the decking can go down in a day. The nails are pricy, but it’s worth it.
OK…look at the picture to the right. The center beam (single thickness 2×8) runs right down the center of the platform, from front door to back door in my case (it is the beam that is sitting on the far left of the picture, and ends at about two o’clock on the post you can just barely see). It is sitting on posts that are spaced front to back, at 0 feet, four feet, 11feet, 19 feet, 26 feet, and 30 feet. The outer facing edges of the first and last posts should be exactly 30 feet apart, and the center beam should end 3.5 inches inside the edges of the posts at each end (to allow for the doubled 2×8 rim joist that will sit outside the ends of the beams). Find the exact center of this beam and always keep track of where the center of your platform will be, at every level…pier, post, beam, sub-floor, etc. You will want this position later.
When running the center beam do not allow a joint in the beam to fall anywhere between posts. Joints should always be sitting directly on the post. Since there isn’t a center post under the middle of the platform, I used a 12 footer to go from post zero to the post at the 11 foot point and from the post at 26 feet to the one at 30 feet, and used an eight footer in the middle.
Hammer a nail part way into the top of the beam near each end and pull a string tight…dammit, I said TIGHT!…between the two nails and carefully move the beam side to side getting it perfectly centered under the string, and toenail the beam in place.
Now you have a good, solid starting point.
Look at the picture again, and imagine yourself standing on the post/beam at the far left.
If your balance is as good…or bad…as mine, this will be followed by your imagining yourself falling and busting your…er…kiester.
Anyway, looking straight down the beam, at each post (four feet, 11 feet, 19 feet, and 26 feet) you want to place a DOUBLE 2×8 beam perpendicular to the center beam with the ends resting on the posts to the left and right edges of the platform. Again, remember to hold the ends of these beams back about 3.5 inches from the outside edge of the post so the double rim joist will still be 30 feet from the platform center, no more, no less.
Either toenail or use galvanized L brackets to attach these beams to both the posts and to the center beam.
At this point it would be a good idea to put some X bracing under the beams from post to post, bracing the structure and giving you another chance to check the posts for plumb and placement.
I know, I know…I didn’t…but then I’m famous for, “Do as I say do, not as I do.”
Now, back on top of the beams…
Left and right from the center beam, along each perpendicular double beam, make a mark every 16 inches. Those marks are the locations for your 2×8 floor joists. You won’t be able to mark the outer joists at the perimeter at this point because you don’t have the rim joist up yet as a nailing point, but you can get the joists for the center four sections placed, which will help steady the platform and, if you nail down the first of the decking, it will keep everything square.
Ease of construction note: At this point, or even before putting any decking down, I would suggest that you put your joist hangars on…it makes things a lot easier. Silly me…I didn’t, and doing so while laying on your back in the dirt (or mud) because you have to, to get to them under the decking is, not fun.
Now put the first band of your doubled rim joist on (single band first so you can thru-nail the ends of the last joists), install the last of the joists, put the second band of the doubled rim joist on, and finish decking the platform. Stagger the short sides of the decking sheets so the joints fall in the middle of next row of sheeting. Let the ends of the sheets that run past the edges run wild for now…just deck everything to or past the edge of the 30 foot circle you are building.
Remember I said you needed to keep track of the exact center as you added layers from the piers up? Now is when you need to know where that center point is. You need to draw a precise circle 30 feet in diameter with that point as it’s center. Use something slightly over 16 feet long to use as a compass, and DON’T use string. String stretches and with varying amounts of tension as you draw your circle you will wind up with an ellipse smaller than 30 feet in some places and bigger than 30 feet in others. I used a 1x4x16 with a nail in it a couple of inches from one end and a hole for a pencil through it 15 feet from the nail, then used this “giant compass” to draw a 30 foot circle.
I thought I would need a jigsaw or reciprocating saw to follow the line well enough to get an accurate cut for the circle, but as it turns out the curve of following the line is gentle enough that it is easy to cut the edge of the platform using a skilsaw. Now you have one more easy step. Unless…
…unless you decide to go with radiant floor heating as I did. We’ll get into radiant floor heating in detail later, but for now, to get the platform ready for the yurt kit, you need to make one allowance for hydronic heating.
The yurt kit is erected on the finished subfloor. With a yurt that will have woodstove heat, or central heat/air, the decking you have down IS the finished sub-floor, but not with a radiant heat floor. You must allow for the channels for the water tubing to be run in for the finished floor to go on top of. The top of whatever material you use for those channels is the top surface of your sub-floor…so you need to make a rim about six inches wide of the same material you will use for the channels around the outer edge of the platform so your effective sub-floor height is above the water tubing, not below it. Since I made the tubing channels from lengths of .75 plywood one foot wide and 8 feet long, I also used .75 plywood for the edging (see the picture).
The last thing you need to do to have your platform ready to erect the yurt is installing a drip edge. This is a band of some thin (.25 inches or so) material that extends at least an inch above finished floor level, and below the top edge of the yurt platform eight inches, and that is attached by screwing/gluing it to the outer edge of the platform. This drip edge performs three functions:
First, it creates a “bump edge” for the lattice walls to “bump” against so they don’t wind up past the edge of the platform and on the ground while setting the kit up. A foot or two of lattice in the middle of a wall section would not cause issues, but more than a couple of feet or the end of a wall section dropping over the edge could cause real problems I think, and I used the drip edge as “insurance” to keep everything on the platform while erecting the kit.
Second, there is a row of grommets along the bottom edge of the outside covering you use to attach the wall covering bottom to the platform, and this is what you screw the screws through the grommets into.
Third, when it rains the water runs down the outside wall, then down the drip edge, then it drips off the…drum roll, please …drip edge! Now…do you know what time it is? It’s…
…time to relax and wait for the freight company to deliver your yurt kit. Go ahead…fix yourself a nice mixed drink. I am. I’m having OJ and sugar free raspberry lemonade. You?