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?

 

[Mouthpear]

Normally the anchors with cables go from the corners of a structure out at an angle a ways, much like tent stakes. This doesn't work because of the driveway. What the other person was suggesting and my husband had been considering was a small anchor or two directly beneath the coop. My husband was thinking the center underneath, I believe the other person said the edge which probably would he hard to implement due to the fence line. The small anchor below won't do a lot but it might do something. But it's also the chickens' main hangout shelter from the rain and I'd rather not do that if it can be avoided.

 

[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.

 

[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.

 

[lothalvalleyfarm]

I see.
That 4' depth really is about as deep as you can go with a raised coop that's not a walk in or reaching everything gets to difficult.

Needing to fit a wheelbarrow under makes the 3' kind of necessary too. Maybe measure the standard wheelbarrow and see if you can drop the floor some giving wind less of a place to grab.

Will you still be able to reach in with a wheelbarrow in place?

I use a big plastic shovel and scoop the coop bedding into a big pot from a tree then carry that to the compost or put under my trees directly. The big 8x14 coop takes 20 minutes to clean and then put new bedding even with a few bossy hens telling me about their day.
It's nice to be able to be out of the weather while tending the birds or treating any injury or illness.
Also being a walk in it's much easier to get adequate ventilation in place.

Just things to think about before you build.

It's up to my husband for the build, not me. The wheelbarrow shouldn't keep me from reaching inside.

 

[GCrumb]

Beats me if this'll help in your situation, but you can sink steel t-posts and bolt the wooden coop legs to them. T-posts come in a lot of sizes now.

 

[Mouthpear]

Didn't you just tell me?

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

Because...

I don't want cables in my driveway where I need to drive/operate machinery.

Now it's...

This was my husband's conclusion,

Then what you should do is pour some concrete pads 12" down, bottom of pad. Make it at least around 16x16. Before it sets stick a J-Bolt anchor in it. No less than 3" from the corner sides. Cover back up with dirt and compact it. Put deck footing and build. Strap it down. This is done when you can't go deep. You go wide.

 

[GCrumb]

BTW, I like the height. I have this situation where it has to be raised or mice will nest under the floor, and once it's high enough to discourage that it needs to be higher so chickens can walk under it and don't want to nest under it so much, and by then it might as well be comfortable to get a rake under there.

 

[Mouthpear]

Normally the anchors with cables go from the corners of a structure out at an angle a ways, much like tent stakes.

They don't have to be. Especially on a small sheds and carports they go as close to the structure as possible. Give me a few and I will draw it up.

 

[SmiYa0126]

@DobieLover any thoughts?