Expert: Arshad Khan - 2/15/2010

Question
QUESTION: estimations is important in engineers so that i need to know how to calculate roofs, slabs

ANSWER: Hi Abdikadir,

The quantities for concrete can be simply worked out- the volumes (area times depth), and the rebar can be estimated by assuming between 40-60 kg/m3 of concrete, depending on type of slab and spans.

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QUESTION: DR arshad thanks for answering the question that i ask you so now i know how to calculate slabs but iwould like to ask you how to calculate galvanized iron sheet roofs as well asbestos cement roof and number of woods

ANSWER: Hi Abdikadir,

Iron and asbestos roof sheets are normally measured in m2 along the slope and then you need to add around 15% for the lapping. In order to get the weight, just multiply the area (including 15%) by the unit weight per m2, which info is usually available from the manufacturer, or else you can weigh one sheet to determine this.

Wooden members are usually measured by either volume or length for specified X-section size. e.g. 2.5m of say 15x10cm section. To get the weight, just multiply the volume by the density of the wood which may vary from 7-12 kN/m3

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QUESTION: dr arshad thanks for answering me,in my university we going write a thesis project fist its needed to calculate all r cc works, if its slabs,beams,columns,then make estimations and costs then foundation calculations,electricity designs piping and architectural drawing which is the fist thing to do, so that is there any other thing needed for me, please i need your consultations

Answer
Hi Abdikadir,

For a complete estimation, the following need to be worked out:

Site clearance, excavations, temporary supports, foundations (maybe piling?), basements, shuttering/propping, concrete, rebar, steelwork, architectural finishes, curtain walling, doors, windows, partition walls, bathroom/kitchen fittings, piping, drainage, fire-fighting, air-conditioning, heating, ventilation, lifts/escalators, electrical wiring, circuit boards, electrical outlets, transformers, water storage tanks, pumps, etc, etc. This list is by no means exhaustive!