Digging foundation beams prior to setting forms?

[Chuck K.]

Looking for some advice on how to dig foundation beams for my shop prior to setting up the forms. This would allow me to use my backhoe to dig beams then set forms and spread sand, lay steel etc.

I know very little about pouring concrete so am all ears here.. My hope is to save some money by putting up forms, digging beams then hire out concrete finishers for the actual pour. From my observations usually the forms are set then the beams are dug by hand which is out of the question for my back and stubborn gumbo soil. The slab will be 64'x60' this would be a lot of hand digging as I may have to go down to virgin soil, I have raised the lot ~20"

Has anyone dug beams first then put up forms and spread the sand? If so how did you keep the sand out of the freshly dug beams??

Thanks for any help.. Chuck.

 

[Alan L.]

For a slab on grade the problem with digging the beams before putting up the forms is that the stakes that hold the forms tend to cave into the beam ditch when you drive them in. I have seen it done however.

 

[jimmer2880]

I'm not trying to convince you 1 way or another. But, I recently put up a 32x32 with a 5" slab. I did all the prep-work for the slab including spreading the stone. Now that the slab has been poored for over a year, I have 6 cracks in it and am not very happy. But, the concrete guy won't back it up because he didn't do the prep work.

If/when I do it again, whomever pours the slab, does the prep also so that they have nobody to blame.

 

[Egon]

Dig and form your beams and then just pour the beams. They don't need much finishing. Then get the slab area prepared for the pour.

Then let the contractors go for it for the final pour.

Make sure you got the required rebar for joining the beam and slab in place.

 

[MarkV]

If you built grade up 20” make sure it is well compacted.

MarkV

 

[EddieWalker]

I'm assuming that when you say "beams" you are talking about footings? The ditch that is dug around the perimiter for a foundation to support the load bearing walls?

At 64ft by 60ft, it sounds like you are building a metal shop? or are you buying some very expensive, very long wood trusses to span that distance? or are you using beams to support the load of the roof, which will require additional footings inside the pad?

Who said that you have to set the footings on "virgin soil?"

Do you have an engineer or city code requiring the depth of your footings and if so, what are they? Most homes that I've built and worked on here in East Texas only have a footing that's one foot deep with half inch rebar in it that's tied to 3/8 rebar on 2ft centers for the rest of the pad that's 4 inches thick.

It's not possible to give you advice without more information.

Eddie

 

[BB_TX]

Are you planning beams across the middle also? I had a 40'x60' slab poured in 2000. They put perimeter beams as well as beams front to back and side to side across the middle. I also have black gumbo with bad expansion/contraction problems. The land sloped from the right front to the left rear a difference of maybe 18". Have only minimal hairline cracks in the slab.
Can't help on digging the beams. I did not see them do it, but I can't imagine they did it by hand. I went out most evenings to see the progress (I do not live on the land). As I remember, the beams trenches were not there one day, but were the next. And those trenches were dug pretty deep.

 

[rural2]

In 30+ years of construction I have never seen footings intentionally dug after the forms are set.
For monolithic pour... Dig footings, set edge forms by hanging form from vertical stakes, brace and line form by "kicking" additional stakes at apx. 45 deg. angle back to bank, use shovel to clean footing prior to setting re-bar, pour concrete, remove vertical stakes from footing before concrete sets up.
Stem walls... Same as above except add another form for the inside face of the stem wall and add U-shaped "jacks" or "scabs" in between vertical stakes to keep form from spreading while concrete is poured.
It's not hard to do. It's is not easy to get it right either... Concrete waits for no one! So make double sure the forms are where they are supposed to be and at the right elevation before it gets there. Oh yeah, if you are not vibrating the concrete tap the forms with a hammer or whatever to get rid of the air pockets "honeycomb" against the form.
Good luck

Looking for some advice on how to dig foundation beams for my shop prior to setting up the forms. This would allow me to use my backhoe to dig beams then set forms and spread sand, lay steel etc.

I know very little about pouring concrete so am all ears here.. My hope is to save some money by putting up forms, digging beams then hire out concrete finishers for the actual pour. From my observations usually the forms are set then the beams are dug by hand which is out of the question for my back and stubborn gumbo soil. The slab will be 64'x60' this would be a lot of hand digging as I may have to go down to virgin soil, I have raised the lot ~20"

Has anyone dug beams first then put up forms and spread the sand? If so how did you keep the sand out of the freshly dug beams??

Thanks for any help.. Chuck.

 

[ToadHill]

For forms you may want to look at pre-formed styrofoam forms. They are not only easy to assemble but they give the walls some insulation as well.

 

[GT2]

Like Eddie said, if your talking about the lower footing; My concrete guy backhoed out the ditch to full depth then just cleaned out the bottom with a flat shovel ( not much digging at all). He then set 2x10 or 12's to make the bottom forms. Then he built the stub wall forms right on top of the footing forms, added re-bar and did a two stage pour one right over the other.