First, lay out the pressure treated 2x4 lumber. Note that at the back, the long pieces extend beyond the cross-beam at the back by about 4 inches. The dimensions can be to your liking, but are approximately 30" x 60".
Fasten the four pieces of lumber together using flat 90-degree joints.
Close-up detail of one joint.
Flip the frame over so the flat joints you just attached are now on the ground, and join the pieces together again, this time on the inside using a different form of 90-degree joint. You could also simply screw the pieces together if you wish.
Next, add posts which will support the coop itself (the rest of the enclosed space will be the "run"). These posts are approximately 24" high -- the height is important as it should be the same height as the width of your hardware fabric you will be attaching later to secure the run from predators.
Attach the posts using additional 90-degree joints.
Use a square to ensure your posts are fastened upright. However, if you are slightly off you will be able to correct this later.
All four posts are now attached to the frame.
Oops! We forgot! Take off the posts, and add a layer of 2x2 treated lumber on top of the base frame. (This is optional, but allows the coop to be a little higher, and makes the front door a little nicer, in my opinion.)
Attach these funny connectors to hold the posts upright.
Screw in each post one by one.
Okay, all four posts are now in place on top of the 2x2 rails. Note the far back 2x2 has not yet been installed for ease of access to the post mounts.
Cut a square out of 3/4" plywood to form the base of the coop. It is important to use fairly thick plywood here so it doesn't sag later on as the majority of the middle will be unsupported. This piece is approximately 32" x 32".
Installation of the back 2x2 rail. This photo doesn't show it, but you should pre-drill and simply screw it into the 2x4 below it.
Installation of the front 2x2 rail. Again, pre-drill and screw directly into the 2x4 base below it.
Form a square to support the plywood floor out of untreated 2x2 lumber. At this point we switch to using mostly untreated lumber as this wood will be closer to the roof and thus more protected from the elements, but also because it will be closer to the chicken's living quarters and is probably safer for the chickens.
Each pieces of untreated 2x2 lumber is cut at a 45-degree angle to allow it to joint with the two adjacent pieces to form a square. The longest part of each piece is 32" wide, enough to span from the outside of one post to another.
Use 1" 90-degree brackets to join the pieces together.
At this point you should have a 32" x 32" square made out of four pieces of 2x2 untreated lumber. You can rest it gently on the four coop posts but it has not been attached yet. If any of the posts are out of alignment, they can gently be pulled or pushed to where they need to go.
Use these funky joints to attach the floor frame to the posts.
Gently place the 3/4" plywood floor on top of the floor frame. Pre-drill screw holes and attach with 1.5" screws.
Once the floor is attached, place a 2x2 along each edge and trace it. Then draw outlines of where you want your nesting boxes to go. This is the time to layout the floor plan of your chicken's future home.
Attach 2x2 untreated lumber to three of the edges of the floor. Notice the fourth edge is left open.
Next put in another untreated 2x2 as a separator between the row of nesting boxes (along the left, where the drill is) and the floor beneath the roost (on the right, where the pencil is).
Subdivide the nesting boxes into three areas. Two will become actual nesting boxes; the third space you will cut out and will become the chicken's entrance to the coop. The two nesting boxes, closest to the camera, are approximately 11" in width, measuring from the outside of the closest divider.
Cover the roost floor with polyurethane. You need to do this now because it will become inaccessible in the next step.
Add hardware fabric over the roost floor. This will give the chickens a walking surface while allowing their droppings to fall through.
Closeup detail of the hardware fabric and 2x2 attachment.
Use a drill to create a holes in the entrance, and use a sawsall to remove the plywood floor.
Attach u-joints at the corners to support additional posts.
The coop floor is shown with a u-joist attached to each corner.
Attach the posts for the walls of the coop. They are about 24" high. Cut pieces of plywood for walls and attach to the posts. The plywood used for the sides is a special grooved plywood for aesthetics.
Attach connectors about 6-8" down from the top of the posts along the wall with the cut opening in the coop floor. These will support a cross beam which will form the basis for the main cleaning door to the coop.
Close-up of one of the connectors to support the cross-beam.
Install the cross beam.
A view of the cross-beam from the other side.
To make the nest boxes, cut two thin pieces of plywood to fit. Make sure to angle the top, which will discourage your chickens from roosting on top.
Cut a door in the nesting box wall nearest to the side of the coop. This will allow you to access the inner nesting box. The door should be 3-4" above the floor to allow ample room for nesting material which you'll install later. Then install the nesting box walls by screwing them to the 2x2 dividers already mounted on the floor.
Install a latch on the nesting box wall door to keep it from swinging freely.
General view of the nesting box with the hinge and bolt installed.
Cut a suitable piece of plywood to form a roof over the nesting boxes, and attach it to the back wall with a hinge.
Final positioning of the interior roof over the nesting boxes. Also note a piece of plywood has been cut and placed along the entrances to the nesting boxes, to allow more nesting material to be placed within the nesting boxes.
A second cross-beam should be installed at just the right height such that the nesting box roof just barely rests on top.
Cut a piece of exterior plywood to fit the entire site, then cut it across so that a piece fits above the cross-beam.
Attach the remaining part of the exterior plywood side using nice large hinges. Be sure to pre-drill the holes (and ultimately the screws are large enough to require a 2x2 backing to avoid injury to the chickens. But we'll get to that later. If you are planning to paint your coop, it may be easier to paint it before installing the hinges (but obviously that's not what I did!).
As you can see, the large hinge screws really stick out and can be a hazard for the chickens, not to mention yourself. Put a short length (6" or so) of 2x2 to receive the screws along the inside.
A view of the interior of the coop so far. At this point we've also cut a piece of thin plywood that can slide in and out underneath the hardware fabric on the right, forming a shelf which can be removed for easy cleaning.
Cut another piece of exterior plywood for the final remaining side. You'll need to cut two access doors -- one for the eggs and one for the shelf (which is attached with hinges in the photo). Using a clamp (upper right) can help position the plywood while you pre-drill and screw it to the frame.