Rebar Quantity Takeoffs

[aswierski]

I've been given the task to calculate rebar quantity takeoffs for some foundations based on another firms drawings. I've never done these before, and have had minimal feedback from my superiors, so I was just wondering if anyone could take a look at this and provide me with some constructive criticism. The actual process is quite easy, so I'm basically speaking of the presentation (unless I'm missing something glaring). Basically I'd like to hear any comments that I could possibly incorporate before I continue to the rest of my takeoffs. Thanks in advance.

 

[weab]

On first look, I think it looks good. What I would want to know is what rebar is required to build certain things and the total order to purchase. Looks like you may have it all.

My only real question cannot be answered without taking a look at your hand calcs. Did you do a "neat" takeoff, that is, exactly as detailed? Or did you add a percentage for loss and waste. Since I don't know who your audience is, I don't know if you need to add 5% or so to your values if you haven't done so already.

 

[StructuralEd]

Don't forget extra to account for lap splices.

When I do any take-offs I add a certain percent for extras and things that might not be obvious to a designer; more apparent to the mechanic.....tie bars, supports, etc.

You will always be in the dog house for being too low if the funds run out.

 

[dik]

I don't know what the significance of the 'surface area' is, but I would normally use a length for rebar; this could be incorporated to include thickness and height to automatically get the quantities of concrete.

I would also use pounds for rebar or tons (tonnes) because this is the way the material is generally ordered.

I would normally use a vlookup to get the bar area based on a dropdown list for the bar size just to make things easier and less likely for an error.

I would break down the weight/cu yd or wt/cu m into the components. The amount of reinforcing per total concrete is not very meaningful, but the pcf for piers, slabs, beams, columns, footings, etc. is more useful.

my $.02... Dik

 

[dik]

Clarification... Rebar is usually ordered by length... converted to number of bars... this is converted to weight... (no of tons/tonnes) and the purchaser pays for so many tons...

Dik

 

[TXStructural]

Remember to look at details for hooks, etc. The length of laps can amount to more than 10% of the total on larger diameter bars. Couplers may be better or required for heavy bars in some places.

It looks like the numbers are for comparing between the two codes. If this is the case, the most important part may be to do exactly the same for each scenario.

If this is for budget, you will probably not be able to figure accurately enough for costing until it is detailed for fabrication and placement. There is loss to cutting and laps which cannot be accurately determined until you know hooks and such, particularly on long runs. Rebar detailers typically account for these, taking fabrication methods into consideration.

 

[JLNJ]

You might break out the anchor rods and embedded steel items a little differently. These items often come with the steel rather than the rebar and the unit pricing could be way different depending on the rod material. Showing the rebar to the nearest thousandth of a pound seems a bit unrealistic as well. Rounding to the nearest pound would more than suffice.