This guide outlines the process I used to build an open-air walk-in chicken coop. It might be more accurate to call it a run. My neighbor bought three hens and a small hen house. The house wasn't big enough for them to live in, but she found that the chickens would tear up her garden if given free roam of the backyard. I volunteered to build a very simple enclosure for hold them in, with plenty of space to run and roost.

Overview

The coop is built into the back corner of my neighbor's yard. Two of the walls are made up of the cinder block walls that mark the edge of the backyard. The other two are simple wooden frames, with a very basic peaked roof, all of which was then wrapped in 1 inch chicken wire. If you wanted to make this free standing or only attached to one wall, you could probably do so by first digging post holes and fixing posts in them with cement.

Sizing

The Food and Agriculture Organization of the UN recommends 3.6 sq feet of floor space per laying hen, which is about what I saw at other sources. That actually doesn't sound like much, but I'm glad to know that I'm above the minimum. I decided on 18 x 13 feet because it looked like a comfortable amount of space for 3 or 4 chickens.

Time, Cost, and Difficulty

This project cost ~$350 in materials and took ~140 hours, plus ~30 hours of assistance from my neighbor or my brother. I would rate it's challenge level 3 / 5. The most challenging step was cutting the corners of the roof. I started this project with just a bit of previous carpentry skills and figured a lot out along the way, so feel free to offer corrections and suggestions in the comments. I think that if I were starting now, I could probably build it in about 80 hours.

Materials:

2x4 lumber beams, 6 feet, x14 -- $3

2x4 lumber beams, 8 feet, x12 -- $4

2x4 lumber beams, 10 feet, x10 -- $5

Rolls of chicken wire, x5 -- $9 each

Hinges, x4 -- $1.70 each

Handles, x2 -- $3.40

Sliding bolt latch, x2 -- $6

2 1/2" deck screws, 1 lb -- $7

1 5/8" deck screws, 1 lb -- $8

2" nails, 1 lb -- $4.30

Masonry screws, x30 -- $14 / pack

Masonry drill bits, x2 -- $3

A weather vane, 1x -- $48 (optional)

Tools:

Hammer

Drill & bits

Circular saw

Hand saw

Pliers with wire cutters

Screwdriver

Protractor -- $0.31

Pencils

Labor:

One person from some steps, but two people for many

Step 1: Build Frame for First Wall

I started by building the front wall. This is the wall in which the doors will sit. I attached a 10 foot 2x4 to 3 foot 2x4 twice to make a 13 foot beam, then repeated a second time. I attached those using four 6 foot 2x4s using screws. I cut two 8 foot 2x4s with angled ends so that I could brace the wall. To do so, I decided on the dimensions of the triangle these formed. I used the Pythagorean theorem to to determine the length of the last side of the triangle, and then calculated the arcsin of the ratio of the appropriate lengths to determine the angles I needed to cut.

Step 2: Attach 2x4 to Cinder-block Wall

In order to attach the wooden walls to the cinder block walls, I first attached wooden planks to the walls, then screwed the wooden frames to those. To attach the mounting plank, I drilled holes with a masonry bit and then screwed the plank on with masonry screws.

Be aware that masonry bits wear out, very, very, fast. I used three on this project to drill about 20 holes.

I then screwed the frame into the wooden mounting plank. This step is easier with an extra set of hands. Once the frame is attached on one side, it will stay standing up on its own. If you are going to stop at this stage, be sure to to add a support on the other end to keep it from tearing off the wall if a strong wind catches it. As you can see in the picture, I laid a 2x4 down on the ground and braced the unattached end to it.

Step 3: Dig Out Space Where Second Wall Will Go

If you have a level space, you might want to just make a second frame for the second wall. In my case, my neighbor's yard had some uneven terrain where that wall would go, so I built it in place. I cleared some weeds and then dug out the ground a bit. I couldn't dig it to be level, so I made three tiers. I laid 2x4s down on the ground and then attached them to vertical beams.

Step 4: Complete the Second Wooden Wall

With the first frame in place and braced to the 2x4s along the ground, its time to build the top of the second wooden wall. In my case, this was 18 feet, so I attached a 10' and 8' beam. I cut a 45 degree angle in order to make a miter joint at the upper corner where the walls meet. For now, the beam can sit on top of the ciderblock wall until it's screwed in permanently. Support this with vertical beams in three or four spots along its length.

Step 5: Secure and Reinforce the Walls

At this point the four walls are in place. Screw or hammer everything together. Add crossbeams where necessary. I think this is a good time to add the doors. The doors are just smaller wooden frames sized to sit in one wall. I made two doors: one regular sized, and then a little one in case I ever want to wheel a wheelbarrow through or carry something large in or out. The doors are attached with weatherproof hinges and slide latches.

Step 6: Build the Roof

Although this whole project was well outside of my previous experience, the roof was definitely the most ambitious part of the design. I searched for some examples to follow and didn't see any consistent 'right way', so I just tried to keep it simple and make it sturdy.

The center beam is a 10 foot 2x4. There are four 8 foot beams extending down and outward, spaced 6' apart. Getting the angles requires a bit of trigonometry. Each of these sloping beams will form a triangle with a base half the width of the coop. The hypotenuse is the length of the beam, in my case 8'. Before we can cut the ends of the main roof support beams we need to calculate what angles to cut.

It's possible to figure them out without figuring out the last leg of the triangle, but I feel more confident filling in all the lengths and angles.

We can calculate the height using the Pythagorean theorem: the two sides adjacent the right angle, squared and added are equal to the hypotenuse squared. Square the hypotenuse and subtract the width squared. Take the square root of this number to get the height of your triangle.

Now we can calculate the angles. Sine of the angle equals the length of the side opposite the angle, divided by the length of the hypotenuse. Divide these and take the anti-sin on your calculator to get the angle.

You can see my math and my dimensions in the attached diagram.

I recommend keeping the length of the sides of the roof a multiple of two. If you do this, it will be easier to cover the roof with chicken wire without having leftover.

Buttressing the legs

The main support beams will tear apparent if they don't have a cross beam joining the sides of each pair. I made mine by tracking a 2x4 and cutting along the line, and then screwing them together. If you're looking for a shortcut, mounting them on the vertical faces of the pairs would avoid tricky cuts and would probably be about as secure. If you wanted to make it really strong, you could add cross beams on the vertical faces of both sides.

If I misuse any terms, please correct in the comments section.

Step 7: Raise the Roof

Once the roof felt sturdy, I lifted one side and set the two legs on the brick wall. Then I lifted the other two legs and set them on the second wooden wall, as seen. The legs can be hammered or screwed into the wooden wall immediately. On the cinder block side, I used the masonry screws to attach a piece of wood to that the top of the brick wall, and then attached the roof to those blocks.

The better way

The way that I did it was a mistake. Once I was adding chicken wire I realized that I needed some wood along all sides in order to staple the chicken wire to something. I ended up laying planks down and screwing them in. What I should have done was lay down 2x4 all the way around the two cinder block walls.

Drill holes in the necessary 2x4s that are the same size as your masonry drill bit. Put the beams in place and drill into the brick with the masonry bit using the 2x4s as guides. Screw the boards down. Then attach the roof to those beams with wood screws or nails.

Step 8: Secure the Roof to the Walls

You can see here my fail. I spent as much effort securing these landing pads into the wall as it would've taken to attach 2x4s all the way around.

Not only would it save a ton of wasted time, but it would've looked much better. Oh well, it doesn't show from outside, thankfully.

Step 9: Connect the Ends of the Central Beam to the Walls

At this point, the roof is in place. It's not secure though, and it doesn't have shape you can wrap chicken wire around. To do that, we need to attach beams on the two ends of the center beam that connect it to the shorter walls at the front and back. Again, you will need to do some trigonometry. To cut these two end beams, imagine the triangles that they form. The base of each will be determined by subtracting the length of the center beam (10', for me) from the length of the whole coop (19') and then dividing that in half, for each end. So for my coop, that base is 4.5'. The height we calculated in the previous step. Square the length and the height, add them, and take the square root to get the length of the end beams. Use your knowledge of sin to calculate the angles to cut each end. Then screw or nail it together.

Step 10: Angle-cut the Corner Beams for the Roof

The final step when building the roof is the hardest, or at least was for me. In order to fully secure the roof in place and to make a shape which we can wrap chicken wire around, we need to connect the corners of the coop to the ends of the center beam of the roof. This means cutting a facet into the end of the corner beams that angles them both downward and outward.

Calculate your lengths

Calculating the length and the angles to cut into the corner beams is fundamentally the same process we've used for other angles and lengths. Each of these forms a triangle. We know the height of the triangle, it's the height of the roof from the top of the walls. The length of the base of each triangle is determined by calculating the hypotenuse of the triangle formed by the corner. This hypotenuse is then used as the base of the triangle formed by the corner beams themselves. This will get you the length of the corner beams.

Calculate the downward angle

To make the tricky facet, first we need to cut joints that will angle the beams downward. Start by imagining the angle formed if the beam were attached uncut. This means that the join has a 90 degree cut, and it sticks straight out. If we divide the length of the beam by the height of the roof and take the arcsin, we get the shallower of the two angles. Subtract this from 90 to get the angle where the beam meets the roof. Using my dimensions, these are 31.4 and 58.6 degrees. Once you cut these, the beam will stick out at a downward-sloping angle, but it's still going to jut out perpendicular to the center beam. Now we need to make a second cut which will angle it outward towards the corners.

Calculate the outward angle

To calculate the second angle we need to cut, look at the triangle formed by the beam if we look at a 2D drawing from overhead. This forms a triangle, with one side determined by the width of the coop in half, another by calculating the horizontal distance between the front wall and the end of the center beam (the length, minus the center beam, divided in half), and the hypotenuse of these length, which is the base of the triangle we used to calculate the length of our beam. What we want to know is the angle which the corner juts from the center beam, if we only concern ourselves its horizontal orientation, as though looking down from above. Once we have this, use a protractor to mark where the new edge will be on the 2x4, and then use a straight edge to connect the line with the opposite edge. Using whatever saw you have available, cut this angle. I found a handsaw to be the easiest way.

Repeat for the other three corners.

Step 11: Attach the Corner Beams

This step benefits from a second person, although it's possible to do it yourself.

Position a beam

Standing on a ladder, place the appropriate end on its corner. Position the upper end against the center beam.

Attach the upper end

Hammer in a nail to keep it in place. Either finish attaching it with nails or drill holes and screw in screws.

Attach the lower end

Move over to the lower end and either nail or screw it to the corner, according to your preference.

Repeat with the other three beams.

Step 12: Finish the Frame

After this, we're going to attach the chicken wire. Now is the time to examine the frame. Finish attaching anything you said you'd come back to.

Attaching the doors

You can attach the door earlier if you like. I actually did it while building the frame.

Although you know the height, measure it to confirm. Decide on the appropriate dimensions, and mark them. Cut a the sides of the door with 45 degree angles and attach them into a rectangle. Check the fit, then attach hinges on to the door. Place it in the frame and trace the holes in the hinge. Drill, then screw the hinges to the frame. Add handles on both sides and a sliding latch on the outside.

I recommend repeating to make a smaller door. You'll only need to use the big one most of the time, but you'll appreciate being able to open the doorway extra wide in order to take a coop or a wheelbarrow through.

Add a weather vane

I suggest adding a weather vane. They're beautiful.

Step 13: Begin Attaching Chicken Wire to the Top of the Roof

I started with the lowest edge of one side of the roof, because I had no idea what I was doing. The first piece was quite crooked and warped, too. I figured out how to lay it well while I worked though. Here's how I should have done it.

Before proceeding, I want to share a critical lesson I learned: chicken wire can behave well, if it is handled carefully. Once it gets bent out of shape, though, it is very difficult if not impossible to massage it back into a long, flat panel of uniform length.

Start at the top and measure

You can measure or calculate, but figure out how long a strip of chicken wire you'll need to fully cover the top two feet of the roof. Even if you calculate it out, measure out and mark two foot increments on the four side beams of the roof. Then measure the length, if necessary. Once you know the length, you'll want to roll that length out and cut it so you don't need to hold up the entire roll.

Roll out the chicken wire

Roll out your roll on the ground outside of the coop. I developed a technique in which I'd set the roll on a bench that was one foot wide. I'd roll out the chicken wire, and as I did, I would bend it back against the edge of the bench with a dowel or 2x4 in my hand. The purpose was to bend the curvature out of it. The goal wasn't to bend it so that it laid flat. Once I cut it with pliers along a clean edge, it almost always still wanted to curl up, at least in places. This is fine, though, as long as it isn't able to completely roll itself back up. The goal is to flatten it as much as is reasonably possible and keep the uniformity of the hexigons intact. You'll notice the difference this makes when you start joining panels of chicken wire together.

Put it place and begin securing it

Standing on a ladder, gently drag the strip of chicken wire into place. Be cautious with it and avoid letting it get snagged, twisted, or kinked as you place it. Once it's in its general location, staple a corner to the upper edge of the center beam of the roof. From the opposite side, work along it's length securing the upper edge of the strip of chicken wire to the center beam, keeping the wire that runs along this edge taut.

Secure the middle

Before securing the entire top edge, reposition the ladder and begin securing the lower edge, starting by securing it to the two-foot demarcations on the side beams. Hopefully, the chicken wire should already be fairly close, and when stapled it should be pulled taut from the top. If it isn't taught when lined up with the demarcations, pull it until it is and then staple it there. Staple along the length of the beam in two or three places.

Secure the lower edge of the end you started

Reposition the ladder and pull the lower edge of the end you started stapling along the upper edge. Pull it so that there is a nice bit of tension between this corner and the upper edge, as well as the nearest lateral beam. Secure in several places along the corner. Bend the excess down and staple it to the vertical face of the corner. Trim the excess with wire cutters.

Finish the strip

Finish along the top, then repeat along the next beam or beams until you reach the far corner. Bend it down and staple it to the vertical face of the corner. This makes it more secure that if you staple on the top side and then trim.

Step 14: Continue Adding Chicken Wire to the Roof

Add the second strip

Below the first strip, lay down a second strip using the same technique as the first. Try and keep the pattern of the chicken wire aligned.

Connect the old strip with the new strip

Joining separate panels of chicken wire together is kind of fun. Where the hexigons are aligned, take the two wires that run along the edges of the strip and pull them across one another so that they overlap the opposite panel. Then, twist them around each other. I used the tips of needle nosed pliers. I stuck them into the space formed when the two wires overlapped, and I twisted until the two wires were tightly wound to each other. If done correctly, they will add evenly to the mild tension in each of the panels.

Repeat with the next panel down

Continue adding panels in strips and attaching them until you reach the base of the roof on that side.

Repeat with and adjacent side of the roof

The next one should be easier, since it'll be a short one.

Work all the way around

It's a little tricky to attach the top edge of the second long side, but be patient and you'll get it.

You should now have a roof entirely covered in chicken wire. Climb onto the outside if necessary, and secure it firmly all over before proceeding.

Step 15: Cover the Sides in Chicken Wire

In my case, I only had two sides to cover. Covering the sides is a lot like covering the roof, except much easier. All of the worst steps are behind us. Enjoy a leisurely coast to the end of the project.

Step 16: Finish Up

Perform tweaks where needed. Chickens are excellent diggers, so consider fortifying the edge of the walls, either by driving stakes along the edge, or burying a strip of chicken wire. Clean up and move the chickens in. Plant beans or another crawler to cover some of the walls with greenery. You may want to cover the whole thing in nylon netting or mesh so that small birds can't fly in to steel seeds. I encourage you to be paranoid about it's impregnability. Predators like foxes and raccoon are known for their cunning for a reason. If there is ANY entry -- and you'll almost certainly discover some in the coming weeks -- other animals will sneak in for seeds, eggs, or chicken. Since building this, my neighbor added netting to discourage birds, and she once saw a young opossum inside, leading me to go around and tighten up all the seams.

The last step of my build was to throw a party to celebrate. This step is optional but highly encouraged.