What Questions for Cement Contractor?

[2YD]

What kind of questions should I ask a cement contractor regarding their work/prep-work etc...?

I've been given the go ahead by SWMBO to contract out a new cement floor for 25' x 60' pole barn that is already up. It's had a dirt floor since it was built probably 25 years ago. I'll be adding a 10'x60' slab on exterior backside of shed for "lean-2" addition and a 4'x60' apron. Bids based on my dimensions have ranged from $5,500 (just cement) to $10k (insulated/pex/dirt work etc..), all putting in at least 4" nominal, 4000psi fiber cement, #4 rebar every 4' and cuts every 8'-10'. Now that I have gotten contractor names and photos of past work, I need to have a few of them out to formally measure and finalize their bids. So what do I ask to winnow down the good, the bad and the ugly?

 

[rimshot]

To start with how about asking for some references. Is his price based on preparing a compacted grade or is it just for concrete and all materials including placing and pouring? What about reinforcing, floor drains, will you clean off splattered concrete before it sets when you dump wheel barrows or spatter up on steel wall panels with pumper before it sets? Is the floor to be poured in one pour? How thick and specifically what type of concrete? Can you show me your license and workman's comp certificates? What assurance do I have that you will pay for your materiels? (if that's a point in the contract) You won't be in need of any leins on your property by materials suppliers. Will you cut joints in the concrete as soon as you can after finishing to try to control cracking?

How's that for a start?

rimshot

 

[framer]

How much fill sand and type of compaction.Type of finish. Slick,smooth,broomed? Makes a difference on quality and longevity of concrete.How level or flat will it be.We pour 5" concrete and rebar 2' centers for slabs like that. I think you said your using fiberglass in concrete? I personally dont like it you cant get a very smooth surface but it is very strong. Sealing helps a lot for sweeping and oil stains.Good luck. Framer

 

[Freds]

I've seen a lot of concrete poured and sometimes they use a vapor barrier, sometimes they don't. I would think inside a building you would want a vapor barrier. That's one thing I'd ask about. Also, a lot of folks don't want them to score it. They'd just as soon have a hairline crack form where ever than a cut mark to trap sweepings and chip when their creeper wheels roll over it. I've seen cracks form 2' away from a cut mark anyway. If there's dirtwork, are they removing the dirt from your property? How soon before you can drive on it? How soon do you want to be able to drive on it? That will determine the type of concrete and the cost/yard.
There's a couple more things to think about.

 

[yooperdave]

The subgrade is every bit as important as the concrete bearing on top of it.

Make sure all topsoil is removed, and replaced with compacted granular fill.

You might consider air entrainmment and maybe some fly ash - makes for a very dense surface.

For a serious sized shed, I would go with at least a 5" slab with 6" of compacted granular fill. Rebar spaced at 4' o.c. is almost worthless. You might consider a 18" or 24" spacing if you want to add moment capacity to your slab.

Good Luck,

Yooper Dave