Foundation Construction

[NewYorkChick]

Hello BYC!

I am building my own coop and it's time to work on the foundation before framing it out. I feel pretty anxious about messing this up which is why I had initially reached out to a professional for help, but he quoted me $8,000 to put in concrete piers! Madness. Needless to say, I am doing this myself. My husband and I decided to do cinderblock foundation (two rows, offset) with poured concrete and J bolts in the holes because our soil is pretty rocky and I'm not sure we're getting deep enough for piers. The ground is not level, so we need to dig one side out significantly before we can set any cinderblocks down. Below are a few specific questions I have about this process, but I have zero experience with foundations/concrete so any general tips or advice are really helpful. Thanks all!

• Do we need to put gravel or sand under the cinderblocks for drainage purposes? Or plastic? Or a French drain system beside the cinderblocks? (this seems a bit much) Seen a lot of different methods on YouTube and not sure what is necessary here. Also, since the cinderblocks will enclose the entire run, how do we ensure proper drainage of water from inside the run out to the field? The grass inside the run is still sloping towards the field, but unsure how the water will escape from behind the concrete.
• I understand that given our climate and the depth of these cinderblocks, we will have some frost heaving. This is of course concerning, but I'm wondering if there's anything I can do in the construction process to help minimize this?
• Any advice on mixing concrete and dropping in J bolts would also be helpful

 

[DobieLover]

I'm in NY too. Up on a rocky, hardpan mountain.
I dug down 42" so set piers for my run. It's 28'x12' with a solid roof. I set 8 piers.
It took me one day to dig the holes with a spud bar and a post hole digger and I poured the concrete and set the J-bolts the next day. I let the concrete cure for 3 days before putting up the posts and beams. The only help I got was to lift the beams into the posts.

 

[mowin]

I'm not going as crazy as DL. My coop will look similar. I built the base on 4x4 PT skids. My area isn't level, so I blocked the lower side to level it out. I know this is going to settle as I build, so once it's built and settled, I'll jack it up and use blocks to re level it. The poles to the run will be bug below frost line.

 

[aart]

The grass inside the run is still sloping towards the field, but unsure how the water will escape from behind the concrete.

Good reason to use piers instead of a continuous run of concrete/blocks.

 

[Alaskan]

We just built our one fancy coop on skids (but it is only an 8x8 ). Two of my other coops have posts sunk into the ground, and the wall of the coop goes about a foot below ground. My duck coop, nothing is dug in. The entire thing just sits on the ground.

My runs have the posts dug in, and the wire between them is dug in too.


My uncle built his coop on super rocky ground... and made a concrete form for the entire perimeter, so the entire perimeter was concrete. He lives where it is super dry... I never noticed it getting muddy... but again, super dry area.

 

[DobieLover]

I'm not going as crazy as DL

You could only hope to be.

Everything I build is built to outlast me and that's all that counts. I'm not spending all my time fixing stuff that wasn't built to withstand the environment it's to perform in.

 

[Silexian]

To keep the blocks from heaving and sinking. You will still need to dig down below the frost line and install a footing. At the bare minimum you would need a 12 inch deep by at least two block width. Compacted gravel footing to set your block wall on. In my opinion piers and beams would be easier and less expensive.

 

[3KillerBs]

Everything I build is built to outlast me and that's all that counts. I'm not spending all my time fixing stuff that wasn't built to withstand the environment it's to perform in.

I come from a family addicted to over-engineering. My father believed that anything that couldn't be expected to last 100 years was a temporary make-do.

I married into a family addicted to over-engineering. My late BIL was an airport engineer and brought that same attitude about safety margins to all his home projects.

 

[saysfaa]

...once it's built and settled, I'll jack it up and use blocks to re level it...,

Have you jacked many other buildings up to level them?

If so, maybe you know things we don't. If not, you might reconsider that plan.

Two observations on it. It is a lot harder to jack up a building than to jack up a car (the only other big thing we have jacked up.) And it is better for it to settle straight.

Ours didn't settle straight. Or wasn't built straight. Or both.

Our foundation was perfectly level. The building wasn't. It was built elsewhere and hauled to our lot where it sat on unlevel ground for a few weeks before he came back to move it on the foundation. The builder got the doors to work by jacking one end up and putting shims under one corner. That made the floor bounce, the blackjack 57 over the floor to crack, some nails in the floor to work out, the windows to not fit, etc.

We jacked it up enough to get the shim out which fixed the floor problems. Then the doors couldn't close. I'd never jacked up a building before. We had a jack designed for similar jobs - not a car jack but still a single jack - not the big forklift the builder used. I still never want to do that again... trying to get the jack under the building was awful, working the jack under that much weight was awful, reaching under the building to get the shim out was scary, letting it back down was awful.

I think much of the problem is everything built (the frame, the wall sheathing, the roof deck, the roofing, the frame for the roosts, ect) braced the lean and rack of the building. It did NOT want to adjust.

It took a LOT of tries with come-a-longs and braces, to rack the front of the building straight enough for the door to close if the weather is dry. It tended to settle back despite the braces. And far too much shaving of the door and the door frame to get it to close in damp weather. It also popped a couple of the wall boards off the frame (our has board and batten walls), and cracked a couple of other boards.

We left the other end of the building leaning.

It looks like your building is about 10x6? That is about half the size of ours. Hopefully that is enough that yours isn't as awful to jack up. I don't think being smaller will help much with the other problems though.

 

[saysfaa]

To keep the blocks from heaving and sinking. You will still need to dig down below the frost line and install a footing. At the bare minimum you would need a 12 inch deep by at least two block width. Compacted gravel footing to set your block wall on. In my opinion piers and beams would be easier and less expensive.

That is not the bare minimum in my climate. Only twelve inches is guaranteed to heave every single year. Then, probably because it is more or less midway down to the frost line, it will not go back down evenly. It would be better to lay it on the surface. It will still heave but at least it will go back to much closer to level for the summers and/or be easier to adjust.