So, in my seemingly never ending saga of trying to save money by digging my own foundation hole (not by hand, but with a small backhoe) I’ve just been hit with a big gotcha from my cement contractor. My carpenter suggested I only need to dig my trenches 4.5 feet deep and 3 feet wide for the cement guy to have enough room to work. Now that I have them all ready and dug, I hear from my cement guy that he needs them 6 feet wide.
Now, yes I am and newbe and have barely any idea of what I’m doing, but 6 feet wide trenches seem like a bit of over kill. His logic was that he needs plenty of room for him to “swing his hammer”..
Am I expecting too much of this guy to be able to work in 3 foot wide trenches?
-David
Replies
what kind of soils do you have? In many cases, the trench is only dug 18-24" and the earth serves as the form for the footing. Maybe I read the question wrong.
Jon
We used to use the trench as its form. Filling with concrete till its still blow grade and falls into the measurement for the block. No longer do they let us do that in northern New Jersey. All footings must be formed now. Makes a huge mess for little addittions.
They have been doing that for years. They just finished a huge sports center at the university where I live using top down construction.
Yes, you're expecting too much. Put the footings in the bottom at 20" wide where do you stand to set the forms? Now put a 12" block on top or the footing. presumably in the center of the hole or close to it and where do you stand? If it's a poured or block wall how do you stand in the trench and bend over to lay block or set forms? The extra space should be to the inside of the foundation if ther is not a slab over the footings. Is this going to have a poured slab on top or wood framing with a crawl space underneath? If it's not a slab you may be required by code to have it dug out with enough room to actually crawl in there anyway.
At 4.5' you need to slope the wals 30*-60*, depending on your soil. Or use anti collapse measures.
Anything over 4'.
3' wide, hmmmn? 8" wall + 15 1/5" forms = 22 1/2". That leaves 6 1/2" on each side to work in. If he uses metal forms, he can pick up 4" more on each side.
BTW, I prefer 3' on both sides of the form. Back fill is cheaper, faster, and safer than fighting small spaces, especially when you've got 2 or more men walking around in there.
Darn! Obviously I hadn't thought about all the facets of the project when I was digging. Now this leaves me with the sinking feeling knowing that my carpenter doesn't know what the heck he's talking about....
Have your carpenter set the forms. LOL
Until you know better, let it be a lesson to ask the guy who it affects , as to what he will need.
will apply to many scenarios.
I'm with SamT--3' each side is about right. More space, or stepped back if colapse is a concern.
Beer was created so carpenters wouldn't rule the world.
My excavator will dig it 3 buckets wide with a bobcat. Theres plenty of room for me to frame the forms and my chubby mason subs to get in there.
You'd do well to pay attention to what SamT is telling you.
A human does not need to be buried very deep to sustain grave injury.
That was terrible. <G>
OK, let's try again.
If someone is buried abdomen deep they can be in serious trouble.
I have seen trench collapses happen. You simply would not believe how fast 1,500 pounds of dirt can move.
First, get a concrete guy. ;-)
How wide are the footers & foundation walls going to be? Usually, the footers are min 8" wider than the foundation walls (4" each side) but your mileage and building codes may vary. Here we don't form footers. The soil is the form. For 8" walls we usually go 20" wide just because that works well with the bucket most guys use and gives a little room for error. With good soil an experienced footer crew of 2 can dig a house footing in 2 to 3 hours. A laser is used to mark the pour level. Then wait for inspector, and then pour in an hour, again, using a laser. My guess is that forming up would double the cost of labor.
The carpenter may be fine with carpentry but don't bother asking him aboiut electrical or plumbing either...
Safety from slides burying a man and room to work are the primary issues.
Attitude is another one. I had a narrow trench as part of a job once where we were between a house and a deck foundation, preping for addition. Space was about 20-22" from form the dirt wall and very hard to work in but doable.
The form guys developed a bad attitude because of it tho and did their worst work there.
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