Preparing a building pad

[rockasawrus]

Yes, without a doubt, it was way more work than I had imagined! We did at least dig up a few big rocks that were interesting enough to become decorative - one is named Toto rock because of it's resemblance to a Toto toilet

Our engineer specified the footing locations. Building is 56x32' with a 10' wide covered porch - the spacing is 8' on center for most of them, which is fairly normal for a pole barn. Some builders will go 10' - 12' spacing, but I think that might call for doubling up the trusses. Aside from the spacing, a lot of details are different than what I've seen others do such as: LVL header notched into the poles which carries 2' on center trusses (no purlins needed - just sheathing on top chord).

Maybe if I had hired an engineer who does more pole barns, the design could have been simpler but I decided to go with a local engineer, and they had a lot of concerns due to this being residential and being 2 stories on one end of the building.

 

[Renze]

Edit; Ah, i see i'm late

The building is a 32x56' pole barn with a 10' wide patio on the front of the building - 4' deep piers and 5" floating concrete slab - wire mesh and fiber mesh as spec-ed by engineer.

The engineer will follow building code, relevant for your geographic location. We put piers 32 inch deep, because it never feeezes that hard here.

So the plan is to:
1) Dig out 10-20 stumps under and around the building pad. These range from 12-36" diameter, thinking I'll rent a 30 ton machine for this.
-Is backfilling with subsoil or fill and compacting with excavator bucket enough? Or should I run a vibratory plate over these?

Always run a plate compactor after digging out stumps. A heavy hitter like a Wacker DPU 6055 is what i hire locally, a 13 horse Diesel, 60Kn (13.5K lbs) not a Honda powered one they rent to settle patio tiles.
Those tree roots are going to loosen soil deeper than you see, so just rent a half ton compactor that hits over a foot deep.

- Not sure what the best machine is going to be for this - I can get a 75hp tracked skid steer or a 77hp Cat dozer locally. I've never run a dozer before so not sure how efficient I'll be with that. Would using the 30t stumping excavator for digging and skid steer for moving material be awkward/overkill? I feel pretty comfortable operating excavators but the biggest I've used is 12ton

The 30 ton excavator probably needs an overweight permit to haul it in, where a 20 ton machine is already a substantial digger to pull some stumps. When you dig the driveway with the excavator, you would need a dumptrailer or truck. Or do you plan on carrying it all away with the skid steer?

3) Bring in fill and compact in 6" lifts. Back corner of building is high maybe 12".

A decent sized compactor can hit thicker lifts. The Wacker rented here, hits 35cm or 14 inches. I am confortable with 1 foot lifts.

Engineer wants 6" gravel/crushed rock under the slab. Would it be worth doing 2" ROB and 4" clean gravel, or just use 4" clean for the whole thing? My wallet is hurting thinking about it.

In my geographic location there isnt any natural rock, so only asphalt millings or crushed demolition debris is available. For an industrial floor, a foot of crushed concrete (un-sieved, fine and coarse mixed compacts best) is pretty standard, but garage floors are usually cast on yellow subsoil sand. You can ask your engineer if subsoil from a borrow pit will suffice. Again, i dont know building code in your area, your engineer will..!

4) Bring in crusher run to bring driveway up to grade

That also benefits from the plate compactor...

So, whatever equipment you use, the plate compactor is the most important step. Make sure to hit that subsoil hard, after you dug out the stumps and before you begin backfilling.

 

[Renze]

Wire mesh is one of those big red flags that scare me when talking about concrete. The biggest lie told in concrete is that they will pull it up when spreading the concrete, and that it will remain in the middle of the concrete while they walk on it.

Rebar on chairs is the standard that has been proven to work every time it's done properly.

Hmm, they tell that where you live ? Sounds like a hack crew to me. Would soon run out of business here.
Even when they do pull it up, if you put the vibratory needle in the concrete to get air bubbles out, the rebar will drop right back to the ground.

They sell small pucks of concrete with a wire cast in, here. But we usually smash some bricks up, to keep the netting 2 inches off the dirt. Although, putting plastic under a pour is standard here, to keep the ground from drawing moisture out too quickly.

Putting rebar nets on wood is a mistake some people make: The wood lets water to the rebar from below, so rust can split up your concrete from the inside. Having less than those 2 inches of concrete cover will cause rebar rust too...

 

[EddieWalker]

I've never heard of or seen wooden chairs in concrete. This might be a translation issue. Concrete chairs are anything that holds the rebar off of the ground so it remains in the middle of the pad when it poured. Concrete blocks with wire in them like you described used to be pretty common, but I haven't seen them in a very long time. Now the most common Concrete Chair is a plastic cone designed to hold the rebar off of the ground. They are super cheap, easy to install, and water proof.

I looked on Amazon to show what I bought the last time I needed them. It appears that they are called Rebar Chairs, not Concrete Chairs. I'll have to try and remember that.

https://www.amazon.com/HERCULES-1-1-Rebar-Chair-Count/dp/B0058I2D04/ref=sr_1_5?crid=38UNEYVQFU399&dib=eyJ2IjoiMSJ9.FrNI5IUiBoZm3ppHtJAB3JH4pPR68Oe5aoF5DTRwXZG8-onGDiqM2uVJjud2VBm1KaiXFF8cE7lqvBQcwsE2vK26rHw3RDUVKsdXZyhQn3vscMdO4zidX80ejIeUk7qvZNZq4rdKLVFnRxHZI1dAMxP2kLcMPax8rcwG6JiNjvETdOlpaQSPHI9g6JUa1Ysl2S-KZBwpYT0p-Va81C24nQkXUyNqh2rwGhx8JpWNj9cMA3bVfSRdgUsApWDMkbxCGJ1hLQmvIBohcfdAI7Y68OpE_4JaLCng0XBmUnf8OJc.X-Q9Q2Xqil1XXV8wr_wO41VAJy3eMfkgwHxRShvVqzs&dib_tag=se&keywords=rebar+chair&qid=1732714373&sprefix=rebar+chair%2Caps%2C257&sr=8-5

 

[Renze]

I've never heard of or seen wooden chairs in concrete. This might be a translation issue.

No, i'm just saying that some DIY guys make the mistake of using decomposable rebar chairs. Bad idea.

Concrete chairs are anything that holds the rebar off of the ground so it remains in the middle of the pad when it poured. Concrete blocks with wire in them like you described used to be pretty common, but I haven't seen them in a very long time. Now the most common Concrete Chair is a plastic cone designed to hold the rebar off of the ground. They are super cheap, easy to install, and water proof.

The plastic ones arent popular here. The concrete pucks neither, the chance of the plastic ones collapsing, or the concrete ones shifting so they tilt from underneath, from the guys bringing in the concrete with wheelbarrows over the rebar nets, or them simply sinking into the sand base, are too big.

Most contractors on small to medium pours just use leftover concrete bricks or tiles, half, or a third of a brick doesnt tilt away from underneath when the pump trucks hose pulsates every stroke, nor they sink when weight is put on top.

And even with a brick every two feet, 6mm (quarter inch) netting needs to be pulled up where the wheelbarrow drove.