Calculating wind load/tipping risk

[lothalvalleyfarm]

We're building our coops and we're trying to account for potential wind issues. We occasionally get wind gusts up to 50-60mph in winter storms here in SW Washington. Our coop will be raised about 3' from the ground on legs, with a coop height of about 5' at the high end of the roof, with the overall height being about 8'. The roof will be a single side slant. The coop is about 8'x4'. Sinking the leg posts into concrete pilings is not an option, there are utilities in the area that won't show up on a dig safe study.

My husband is concerned the wind could tip it over. We will probably anchor it against the run posts which are 4x4's sunk 3' down into the ground with no cement. Putting RV/mobile home anchors with cables isn't really an option either. The wind here predominantly comes from the south blowing to the north, and sometimes from the west blowing towards the east. The other two directions are rare. The large 8' wide side of the coop will be getting hit from the south broadside by the wind. Our property is very open and flat/rolling hills with a few spare trees. There's a 30x36 shop maybe 40 feet south of the coop that might act as a windbreak, but we're building 4-6 coops eventually like this in the area. We aren't having a lot of luck trying to figure this out with calculator's online. Does anyone have any idea of how this might hold up against wind?

 

[SmiYa0126]

@DobieLover any thoughts?

 

[Mouthpear]

Putting RV/mobile home anchors with cables isn't really an option either.

Why? Why are they not an option? Why have you already counted them out?

What are all the other buildings' foundations made of? Have you already looked to your local wind storm regulations for your area? They will often will have recommendations (but not regulate) for sheds and non attached buildings. You should also be looking at contacting builders in your area to get recommendations.

 

[lothalvalleyfarm]

Why? Why are they not an option? Why have you already counted them out?

What are all the other buildings' foundations made of? Have you already looked to your local wind storm regulations for your area? They will often will have recommendations (but not regulate) for sheds and non attached buildings. You should also be looking at contacting builders in your area to get recommendations.

Because it's adjacent to my driveway and I don't want cables in my driveway where I need to drive/operate machinery. Also for the same reason I can't sink stuff with cement easily, there's a lot of conduit in unmarked locations plus water/septic.

The county code for houses is 85mph. There's 0 data I can find beyond that like how one achieves that.

 

[Mouthpear]

Because it's adjacent to my driveway and I don't want cables in my driveway where I need to drive/operate machinery. Also for the same reason I can't sink stuff with cement easily, there's a lot of conduit in unmarked locations plus water/septic.

The county code for houses is 85mph. There's 0 data I can find beyond that like how one achieves that.

Sounds like you are between a rock and a hard place. Again I say you need to contact local builders. Craigslist or local forums may have people who have experience.

The only thing (without actually seeing it with my own two eyes) that I can think of is expensive. And labor intensive.

 

[Captain13]

Why not dig holes under the edge of the coop as deep as you can (maybe 12 inches about 12 or more inches in diameter) in 4 places. Buy four mobile home anchors. Fill the holes with wet Quick Crete. Stick the anchors in the wet angled under the coop at about 30-45 degrees. Then tie to your base. The cables won’t be in your driveway. Utilities should be more than a foot down so that shouldn’t be a problem.

 

[lothalvalleyfarm]

Why not dig holes under the edge of the coop as deep as you can (maybe 12 inches about 12 or more inches in diameter) in 4 places. Buy four mobile home anchors. Fill the holes with wet Quick Crete. Stick the anchors in the wet angled under the coop at about 30-45 degrees. Then tie to your base. The cables won’t be in your driveway. Utilities should be more than a foot down so that shouldn’t be a problem.

This was my husband's conclusion, except I don't think they make the anchors in 12" typically they're several feet long as as far as I know.

 

[21hens-incharge]

What are the dimensions of the coop? I saw there is an 8' side. Is the other dimension 4'?

Is there a reason to have 4-6 separate coops?

It's less material and more wind resistant if you could go 8x8 and walk in style.

Just a suggestion along with genuine curiosity.

 

[lothalvalleyfarm]

What are the dimensions of the coop? I saw there is an 8' side. Is the other dimension 4'?

Is there a reason to have 4-6 separate coops?

It's less material and more wind resistant if you could go 8x8 and walk in style.

Just a suggestion along with genuine curiosity.

8x4 yes. My husband doesn't like the walk in coop style, thinks it's harder to clean. We're making coops we can rake out into a wheelbarrow or cart that fits under the coop. We're making our chicken set up in a large oval shaped area divided into 4 quadrants. We can keep 4 flocks or rotate as needed to improve the quality of forage by not letting them destroy the grass etc.

 

[Cinnamon Roll]

We had a similar problem and solved it by making concrete feet for the coop. We used tube forms around the legs of the coop and filled them with concrete so the whole thing was much heavier and the center of gravity was much lower.