If you aren't too far along in your run build, have you ever considered cattle panel hoops? That's what we did, and it has exceeded our expectations! It was inexpensive, easy for us two old, (and me partially disabled) geezers to do by ourselves, was easily expandable, and has room so we can stand and work in it instead of being all hunched over trying to herd chickens!
We pounded 8 steel fenceposts into the ground (4 per side), then arched 3 cattle panels between them, secured to the fenceposts with wire we twisted. We draped and anchored chicken wire to the panels to prevent overhead predators and exclude small birds, then we ran hardware cloth up about 2 feet, literally sewing it into the frame of the cattle panel and chicken wire with a roll of wire intended for electric fences. At the bottom we folded the hardware cloth outward another 2 feet or so and used landscape fabric staples to anchor the apron to the ground.
It's all worked beautifully. It withstands our 60+ mph Wyoming winds, snow load, and looks just as good today as the day we finished it. It's so sturdy we can even hang the 5 gallon water bucket and feeders from the top. We put white vinyl lattice up in front of it because we live on a corner lot in town and the setup is visible from two sides of the street. For shading, we just tossed a roll of landscape fabric over it. The landscape fabric is "sewn" to pre-drilled metal lath strips we bought at Lowes and we can roll them up or down like window shades to control how much sunlight goes in. It's breathable, so stagnant, warm air doesn't collect at the top like it would with a tarp. When it rains, the rain runs down it instead of soaking in. (Have you ever put that stuff down then watered? The water stands on top and then runs to the nearest opening, not soaking in right away)
Notice how the center panel of landscape fabric is rolled up in the center the day this was taken.
Snow load? No problem!
We cover most of the run with clear plastic in winter, allowing for ventilation of course. Warm enough in there, even here in Wyoming, to have a brooder set up with chicks being raised with just a heating pad.
Edited to add: On nice days the shades are rolled up to the top for lots of sunshine. And because they don't go all the way to the ground on the east and west sides, sun comes in in the morning and the evening. They do love to bask in the patches of sunshine!
Edited by Blooie - 3/30/16 at 7:02pm