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Chat with a structural engineer made me question my whole approach to control joints
Met this older engineer on a job in Denver last month, dude straight up told me my joint spacing was too far apart for the slab size we were pouring. He said for every 10 feet of slab, you want a joint at minimum every 8 feet if there's any chance of heavy loading. I've been doing 12 foot gaps for years cause that's how my old foreman taught me, never had a complaint but now I'm second guessing every slab I did. He pulled out his phone and showed me photos of cracks that formed right where he predicted they would on a warehouse floor. Makes me wonder how many hairline cracks I've just accepted as normal when they could've been prevented. Has anyone else had their whole method challenged by someone from a different trade?
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violamurray2mo ago
Old foreman of mine swore up and down that you could get away with 15 foot spacing if you used fiber mesh in the mix. We poured a big parking lot outside a strip mall, looked great for about two years, then a forklift drove over one of those long spans and boom, crack ran damn near the whole length of the slab. The mesh just held the pieces together, didn't stop the split. That guy still thinks he's right too, says the crack was cosmetic.
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zara5722mo ago
That 8 foot rule hits different when you see the actual proof. I used to think anything tighter than 10 feet was overkill, but seeing those crack photos changed my whole mind.
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