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Floor joists in an 8x12 coop

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by Hillia, Apr 5, 2014.

  1. Hillia

    Hillia New Egg

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    I'm planning my first coop. I'd like to make it 8x12 to accommodate a large flock, which I hope someday to have. I'd also like to raise it about 12" from the ground so the chickens can get under it in the summer for shade (there will be other shade available). We're using 2x6"s for the floor joist, with 4x4s in cement deck piers. How often should there be a pier support for the joists? I'm drawing now with a pier every 4', but that seems awfully overengineered for a building that will just have chickens in it 99% of the time. Can I get away with every 6'?

    Thanks!
     
  2. Egghead_Jr

    Egghead_Jr Overrun With Chickens

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    You can get away with only post for 4 corners, for more support you can add a post at 6 ft on 12 ft side which is a good idea as the actual floor joist will be attached to that frame. Double up the outside joist, screw 2 together. Also you only need 2x4's for the actual floor joist. Run them the 8 ft length. If attached with joist hangers will support 50lbs per square foot which is residential building code.

    I'd give more than a foot for chicken use under the coop. 18" would be good and 24 inches if you ever need to crawl under there to grab a chicken.
     
    Last edited: Apr 5, 2014
  3. markhaley

    markhaley Out Of The Brooder

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    I'm not a eng. but I have built a few things. I would put one at each corner.and one in the.middle of the 12' foot length side. since your using 2x6 on your floor. that should be great.
     
  4. Hillia

    Hillia New Egg

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    Thanks for the info! I thought I was overbuilding but I couldn't decide for sure. I'll post pictures as it gets built!
     
  5. Huntered

    Huntered Out Of The Brooder

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    I used 2x6 on 16`` center for my floor joists with joists hangers, just to make it more solid.my coop size is 8x12.
     
  6. Egghead_Jr

    Egghead_Jr Overrun With Chickens

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    If you did use 2x6 for floor joist then 2ft on center is sufficient. You've got to keep in mind a residential building is designed for 50 lbs per square foot of load. A 2x4 16 inches on center provides that for 8 ft span. That means it can hold 8x12x50 lbs (that's over two tons) without deflecting past residential code. To hold that load the frame on 12 ft side needs to be doubled 2x6 (glued and screwed) which will hold 1600 lbs, more than half the total load your floor is designed for. And that's without a center post. With a center post you don't need to glue them and jumping up and down in coop will barley defect floor.

    Again, that's all residential code. For outbuildings like barns, sheds and coops the needed lumber size and spacing is even less.

    Typically where buildings fail is not the size of wood rather how it's connected, joist hangers provide proper connections. I cringe when I see massively over sized lumber with 15 or so nails via nail gun for a connection.
     
    Last edited: Apr 5, 2014
    1 person likes this.
  7. tammyfarms

    tammyfarms Chillin' With My Peeps

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    Egghead_Jr,

    Just to make sure I understand your recommendation, use 4 posts on corners plus an additional post on the 12' sides. For the floor joists, should I use 2 2x4s on each outside wall screwed together (essentially making a 4x4) or 2 2x6s (making a 4x6)? My coop is going to be 18 - 24" off the ground and 6' x 12' with a wall in the middle to create two 6x6 coops. The inside of the coop is planned for 4' high at the peak and 3' high on the back. I do not plan to walk in mine but want to make sure I build it strong enough to not fall over. The walls will be plywood and the roof plywood covered in tin. There will be a floor of plywood also. I must also have exterior next boxes.

    Has anyone seen a design that allows for the exit door in the floor with a ramp that runs under the pen? I would like the chickens exit and enter from a hole in the floor to a ramp that is protected from weather by the floor of the building. I also want it to open and close using a sliding piece of plywood in a rail so it can be closed from outside? Think of an old style cutting board that they used to install in kitchen cabinets. My thought is that the door and the inside of the coop would be protected from blowing rain.

    I appreciate the help! I am getting to be a pretty good chicken coop builder... but I have a lot to learn.
     
  8. Primo

    Primo Chillin' With My Peeps

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    As egghead said, make it taller, they are going to lay eggs under there once and awhile and you will need to get them. If it were me, I would use 2x4 joists, then run one 12' 2x6 underneath down the middle supported by a couple of those piers. Cheaper, simpler and no bowing of the floor.
     
  9. screasy

    screasy New Egg

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    I am reading this post with much interest. I am building a coop that is 16 X 12 to accomodate up to 50 chickens. They will have access to an outside run. The main question is about the floor. I have decided to elevate the floor, and now I need to decide on the joists and how to attach it to the ground.

    I have about decided to go with 4X4's resing on concrete deck piers with 2x6 joists. The question is for a 12' span, can I use 2' on center for the joists, and how many piers should I use? What about piers in the middle?

    THANKS!
     
  10. Egghead_Jr

    Egghead_Jr Overrun With Chickens

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    If you use piers in the middle then you'd be making a beam those piers would support and have two spans for joists. If that's your want then go ahead but it's easy to get 12' lumber so why not just have a 12ft span. Use 2x8's graded structural or No 1 and spacing of 2ft. I'd use joist hangers for best connection and wouldn't even hesitate with 1/2" plywood screwed down. There will be deflection when you walk on it but that's outbuilding construction. If you want the floor residential code- no deflection then space it 16" on center.

    2ft on center spanning 12' will carry over 30lbs per square foot (now don't think that it's only 30lbs rather that weight over the entire floor as in you could put 30lbs every square foot and floor would easily hold it-3 tons spread out) so some spring when large person walking. 16" on center with select grade is 60lbs per square foot load- over residential and no deflection whatsoever.

    Forgot about your piers. I'd just do 6, 3 piers along each 16' end. That's what is carrying the load of the joists. As you'll never be carrying 3 tons in it, just double up 2x10 (I'd use the 10") or 2x12's for the two beams. With 4- 8 footers per beam you'd cut one 4' so the beam has a joint overlap of 4' and nail or screw the boards together. The end boards of your joists you'd keep same depth as the beam just for construction purpose so a 12' 2x10 or 2x12 nailed onto the two beams to complete the square.

    I never know if I'm being clear...so will quickly recap. a 16' beam (2-2x10 wide nailed together- 4',8',4' nailed to 8',8') on each end over three piers each, two 12' boards same depth as beams to complete the outer floor framing. That leaves 7- 12' 2x8's spaced 2ft on center with joist hangers (14) to connect to the beams. Yes, the piers can be pressure treated 4x4's right out of the ground from frost depth or use 8" sonotubes and put bag cement in, devolop around the 4x4's last 12" of sonotube.
     
    Last edited: Nov 5, 2015
    1 person likes this.

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