IMPERIAL VS METRIC DESIGNS
The US Federal Government has mandated that all federally funded construction projects be designed in METRIC. Since most Department of Transportation (DOT) needs some federal funds their design is commonly in METRIC. There is still a strong holdout in the private sector and even in some other States.
Because rebar is still price per HUNDRED POUNDS (CWT), estimating rebar still requires that the final result be expressed in POUNDS (LBS).
The practice on Metric jobs, is to estimate in Metric to easily conform with the drawings and resulting weights converted to pounds.
The standard practice at GVS for supporting rebar is as follows:
1. To support rebar from dirt, such as column pads and mat foundation, 3" wire blocs are provided every 16 square feet of concrete or @ 4'-0" spacing each way.
2. To support rebar from dirt, such as continuous footings or grade
beams, 2 row of 3" wire blocs are provided every 4'-0" on centers.
3. To provide cover for wall steel against dirt, 2" wire blocs are provided every 16 square feet of wall.
4. To provide cover for wall steel at interior faces, 1" wire blocs are provided every 10 square feet of wall.
5. 3 rows of 1-1/2" wire blocs every 4'-0" are provided in columns for clearance to forms.
6. Beams are supported by 2 rows of 1-1/2" Beam Bolsters running the length of the beams rounded off to the nearest 5 foot.
7. Upper Beam Bolsters are provided to for multi-layer beam bars @ 4'-0" on centers.
8. Stirrups support top Beam bars.
9. In the west Coast - Stirrups are taken off capped and not as single piece closed stirrups.
10. In Slabs, a combination of half bar chairs and half slab boosters supports the bottom bars and high chairs supports the top bars.
11. Standees are provided in lieu of high chairs if the chairs are greater than 8" high.
12. Joist chairs are provided for joists.
13. Bar chairs are provided for slab over joists or waffle slabs, with top joists bars being carried by the slab.
14. High Chair for Metal Deck (HCM) is provided to support reinforcing steel on metal decks.
It is GVS practice to always include bar supports and tie wire in the estimate.
Fabricating reinforcing bars are reported into the following separation to properly calculate extra charges:
LIGHT BENDING. All #3 bent bars, all stirrups and ties, and all #4 through #18 which are bent at more than six points in one plane, or are bent in more than one plane, or bent with more than one radius, or a combination of radius and other type bending in one plane.
HEAVY BENDING. Bar sizes #4 and larger, which are bent at no more than six points in one plane and single radius bending.
SPECIAL BENDING. All bending to special tolerances, all radius bending in more than one plane, all multiple plane bending containing one or more radius bends.
COIL BENDING. All bending of COILED REBAR by automatic benders. Generally limited to size #3 through #5 with dimensions of the fabricated rebar within a 5-foot diameter limit. Some fabricating shops that are equipped with COIL 20 MF benders are able to bend to size #6 coil.
STANDEES AND SPREADERS. Reinforcing steel primarily use as accessory is sometimes separated to allow the fabricator an option to add or not to add an extra charge. In an installed market, these items are sometimes considered a "gimme".
Special Metal Tags are reported if specified as an extra charge.
Estimating and Detailing are priced per Ton (2000 lbs in Imperial, 1000
kgs in Metric) and converted to CWT. Tagging is included in fabrication cost.
Shipping is priced per 100 pound of rebar (CWT) - once as Freight-In
(Materials coming to their yard) and again as Freight-Out (Materials being delivered to the Jobsite).
Bar end preparations are priced each.