Rebar/ labor costs?

[USAFpj]

The initial contract- a 4in, fiber reinforced at 3,000psi slab was going to be poured in a 30x50 shop.

After being concerned about settling and fill compaction issues, I've wanted to now add 10mil vapor barrier, #4 bar and placed 16oc. The last request was that no water was to be added at the site.

The project manager then stated that my requested items would cost an additional $3,600. I must be out of touch with reality, because the manager is a good dude who shoots it to me straight. Between the rebar and 10mil barrier, that's maybe $700 in material... at the most? He says he needs a pump truck because of the added bar?

In his defense, he does not have access to all sides of the shop- but the front door is 12ft tall for his truck. Can you guys educate me why I'm out of line, or is it the rebar labor that is killing this budget? :confused2:

 

[SSdoxie]

Rebar needs to be installed, supported up on stakes so it is middle of the concrete. This will prevent truck from backing in and/or use of wheel barrow to move concrete to rear of the building, thus need for a concrete pump rental.

 

[s219]

There should be no major cost for the vapor barrier -- $100-200 tops -- and I assume you would always want that -- can't think of a reason to go without or why it would be related to compaction. Cost is basically materials and a few minutes time to lay it down. If the truck is indeed going to back inside for part of the pour, the barrier would need to be unrolled as the truck moves forward, so that's a little more hassle but not a big deal.

If there are soil compaction issues, best to address those directly instead of trying to beef up the slab with rebar in my opinion. I think it's expensive to deal with this via re-bar, and that's still no guarantee. Don't know what it would cost to get machinery in to properly grade/compact the site, but that is less man-hour labor intensive and surely can be done for less than $3600 unless a lot of fill was required.

 

[bigtiller]

Have you inquired how tall the concrete trucks you plan to use are? I haven't seen one that could get under a 12 foot tall door. Also, if they aren't allowed to add water on-site, he will order the concrete delivered with the slump he likes to work with.

 

[USAFpj]

I guess the reason for the pump truck is because of the rebar.. they won't be able to use the chute?
Price of rebar is at $5.20 a stick, so unless their math is off, just not sure where the $$ is. I'd just as soon as not worry about reinforcement as this is a non weight bearing slab, but I just have a hard time trusting the fill- 4ft of it, and the pad was damp when being leveled. The grader said the top portion was pumping a little- that was 2 months ago. It should be dry now, but not sure how compacted it is.

 

[Handloader109]

Rebar would help a bit, but it won't stop cracking..... If this is all fill, it might all settle the same, but probably not. Why not bump up the psi rating to 4k or even 5k that way it won't Crack. I had a slab poured a few decades ago than it was all fill an d probably half washed out. Never cracked, 5k concrete. My shop had corner fill, remaining area was solid. It cracked after a couple of years, only 3k concrete....

 

[Streetcar]

Your cheapest option is thicken the slab or use stronger concrete mix
Rebar adds little to the slab strength but makes the concrete harder to place. 16 inch spacing is too wide to be effective. The rebar price is high because truck can not drive on subgrade and pump is required
For strong slab without cracking you should be concerned about water/cement ratio not if water is added at the site

 

[buckeyefarmer]

Mine. Is 48' long, with rebar. No cracks after 5 or 6 yrs.

Poured half from one end, half from the other.
Do you have a window to pour thru on the back side?
If no insulation remove a couple pieces of siding to pour on the back side?

 

[kspring61]

I just went thru this. Amish builder I had do the pole building recommended going to 5K PSI, like others have said here versus rebar. I am storing a 12K 5th wheel in the building.

 

[s219]

Just replied by PM, but I recommend making a couple bore holes with a post hole digger or soil test auger to see exactly what's happening down below the floor base. It would be good peace of mind either way.