I’ve been watching the construction of a stripmall near my house. It is a single story building, on grade, with no basement. I’m watching the workmen pour the foundation footings, and they’re not using formwork, just digging a trench, placing rebar, and pouring! Is this kosher? If its not neeed, what are the pros and cons of going to the trouble of building formwork anyway. I can’t recall seeing anything commercial built without it before.
This is just a quick response, and by no means meant to be the only answer.
What they are pouring is a slab-on-grade with a turned down edge or possibly a grade beam. If the soil is firm enough, you can do this without building forms. Forms are to hold the concrete in place when there isn’t soil next to it (or when the soil is not stable). If they had excavated for the basement, then they would have needed to build forms to make the walls. Footers for foundations often don’t get formed.
These are general statements, obviously.
When I was a teen working for my dad under concentration camp conditions, this is how we did it. It can save a lot of work, but it can be hard to estimate the amount of concrete needed, especially if the walls nd the depth is not even. Nothing can be more agravating than thinking you just have a short day of pouring foundations and then it turns out that HE underestimnated by a couple-three yard and having to stay till dark to complete the pour.
They’re not even compacting the soil? Holy shit, do you live in an area where they have lax building codes. Then again, you’re probably looking at a developer who knows that he can exclude any problems with that out of the leases and let the owners of the businesses live with whatever happens because of this. If you live in an area that doesn’t have a terrible frost-thaw cycle, I could imagine them getting away with it, otherwise it sounds like someone’s getting screwed. A call to your municipal bulding department should clear the question up.
All his adult life my father was in charge of building large concrete buildings. So as a result I hung out at a lot of job sites and have seen lots of footings. I have even dug a few.
Yes, you just dig a trench for the footing. A form is only to keep the concrete in place. The dirt will do just as good (if not better) job. Rebar is added in the trench before the pour (spaced off the bottom and sides of the trench). sometimes a single 2X4 is mounted in place to give a level for the top of the foundation. This may also give the location for the anchor bolts for the walls, if the building is framed.
This was for buildings built in Southern California.