concrete contract wording

[swharris]

Swharris,
Looks like a nice shop. Hope this thread helps.
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Dan,

Thanks. At this point it's all just pie in the sky. I have a GC I really trust, but he is a finish carpenter by trade and not sure how much he knows about concrete or how much he trusts his cement guy. This is why I'm trying to learn as much as possible. My wife thinks I'm nuts obsessing over all this when there are so many other things to choose/pick out. I agree, but I'll kick myself if it turns out bad due to the fact I trusted some mud slinger who does not care and just wants to get the job done.

I'm hung up on what to do with footings for a two post lift. Put footing columns in specific places (under the uprights)which I don't have their placement in stone on the plans, or make a rectangle of thicker material bridging both upright footprints??

I've already learned much from this thread, so yes it is helping.

 

[BlackTalon]

Sorry -- did not see swharris's post or DieselDan's posts until just now. Mix/ sliump for a footing is not really the same as what you want for the slab. Higher slump isn't necessarily bad if you acheive it with admixtures that do not send the w/c ratio through the roof.

Usually the concrete placers/ finishers are not the guys who own the concrete plant and trucks, so they really can't add water tot the mix. Hopefully the driver does not mess with the mix in the truck. Of course that is where test cylinders come in though -- it is how you can check after the fact to be sure the concrete has the required properties. The question is whether you are willing to pay to have cylinders taken and tested, and you also need to write into the contract what happens if the required properties are not met. cylinders are the norm in commercial and institutional construction, but for residential the added cost means it usually is not required unless it is a requirement of the permitting agency.

This is where it is important to do your homework when soliciting/ awarding concrete bids. Ask them the questions that concern you, and included requirements based on their answers in their bid/ in the contract.

To more directly address swharris's post, you indicate a monolithic footing and slab, so I'm guessing you are really talking turned-down slab edges and not real footings that support a foundation wall? If that is the case the mix used should be a slab mix. Give me a day or two to get some better/ more complete info to you.

 

[BlackTalon]

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I'm hung up on what to do with footings for a two post lift. Put footing columns in specific places (under the uprights)which I don't have their placement in stone on the plans, or make a rectangle of thicker material bridging both upright footprints??

You really don't want to install the poists on columns, it's best to thicken the slab. But check the lift installation guidelines; depending on the base plate design you may be fine with a typical 4 inch thick wire-reinforced slab. If you need more then that the lift installation instructions usually spell it out. If they indicate a normal slab is okay but you want more piece-of-mind, thicken the general area where you think you will install the slab by a few inches and have rebar mats installed in that area. Do it as one full area versus separate areas for each post, as it will give you flexibility in the final lift placement.

FWIW, all my specific 2-post Bend-Pak requires is a 4 inch wire-reinforced slab.

 

[Diesel Dan]

X2 with Davids advice for the lift. I'm going to thicken the slab under the posts and have a stick of rebar go through the area, placed where the mounting bolts will miss it.

I do believe I found my footings contractor. He is not concerned about the 5" slump or vapor barrier. No problem just quoting labor either since I have most supplies on hand. He was recommended by the GC who moved.

I'm ready for a little good luck anytime now.

 

[BlackTalon]

For a slab with integral 'footings' I would be start with what would be known as a VDOT Class A4 General concrete mix. That is 4,000 psi, #56 or #57 aggregate, a maximum w/c ratio if 0.45, a slump of 2-4 inches and an air content of 6-1/2%.

That is a starting point for discussion with a mix designer at a local redi-mix plant (I know what is okay for the region where I live. work, but not where you are). Being in So. CA, the air entrinment may not be needed, or it may be normal to provide a lower amount. Water-reducing admixtures and superplasticizers can be added to increase slump while controlling the w/c ratio.

 

[Diesel Dan]

Got the footers poured.
Decided to skip vapor barrier under the footer.
Per the slip it was mixed at 3500 psi, 4" slump, 10 yards and looks like 10 gallons of water added on site. Luckily we did get it poured before the next round of rain showers. Cloudy with showers on/off for 3 days or so should help slow the curing somewhat.

Will post pics when I can, having issues right now.

Side note, co-worker is have a new home built in the area. Showed me his footer pics, no vertical rebar at all. Contractors response was only needed if 10+ course tall. Talked to building department and only needed when unequal fill exceeds 4 ft. That may be code MINIMUM but is not correct, IMO. I've personally seen high winds(100mph) take off additions and take the top row of block as well since there was no rebar.

 

[pauls340]

Dan, i'm a third generation out of 4 in the construction industry here in SE Michigan. I didn't read your complete thread but one trick i've learned looking for a quality concrete contractor is to go by a large commercial project and find out who the concrete finishers are. They will have several people on that crew who will do side jobs on the weekend. Just one option

 

[sledneck32!]

OP, I really applaud your efforts here to make sure everyone is on the same page! It's nice to have everything spelled out ahead of time instead of arguing after the fact what the contents of the verbal agreement were.

Fyi, this is why commercial contractors cost waaaaay more than residential. Because the specs are spelled out to a T. And ya better follow em or you might be in trouble lol.