All columns are figure from the floor slab below to the underside of the beam or slab above- in other words, the contact area. The formwork is twice the width plus twice the length times height of the column. The concrete is the width times the length times the height of the column. Please notice that in the quantity takeoff illustration, exterior columns are separated from interior columns even though both are tabulated on the same sheet. Both columns are figured the same way and they might be grouped together except that if you have too many exterior or too many interior columns, it isn't easy to find an average price since they do not cost the same. The two types of columns will cost about the same for materials, but your erection labor will cost considerably more for exterior columns. Exterior columns must be braced on one side only, and this takes more time. If you have a high-rise building that goes perhaps 10 to 20 stories, then it is possible to figure about five re-uses of material. But if you plan to re-use square columns, you've got to consider that you can't re-use them just as they are because there may be a slight difference in floor height. Even if there is not height variation, you've got to take them apart and put them back together, and you will lose some of your bracing lumber. To figure re-usage add about 20 percent to the material cost to cover the cost of moving from one floor to another. Exterior and interior beams can be discussed together, but they must be figured separately. The formwork for a beam is the contact area, including the beam bottom and the two sides added together times the beam length. The concrete is the width times the depth below the slab times the beam length. The beam length is figured continuously over all columns. I keep exterior beams separate from interior beams because of cost. There is a considerable cost variation involved in framing beams, because you've got to build an outrigger knee brace for an exterior beam. This brace is used to support the outside beam form. It is also more difficult for men to work on an exterior beam.
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