Arc202b

1. Arc202b Concrete formwork for footing reinforcing for footing concrete for footing

2. Forming footings • after all excavation is complete the next phase in construction is the footing

3. Footing • materials used in footing construction: • wood stakes • to keep forms in place and level • 2” x 6”, 8”, 10”, 12” lumber or metal forms • reinforcing bars ( rebars ) • to give added strength if required • concrete ( minimum of 15 MPA )

4. Information that must be considered for footings • form preparation • embedded item placement • placement of concrete • finish, curing and protection • form removal and cleaning

5. Calculating forms for footing • use the longest dimension of the foundation wall, times number of sides to be formed • length’ of foundation * number of sides = lf • lf / length’ of wood member = # of pcs • add # of pcs together and roundup = sub total • sub total * waste factor = total # pcs • roundup to whole pieces ( 33.25 = 34) • example • 22’ x 2 sides = 44 lf, 16.66’ x 2 sides = 33.33 lf • 77.33 lf /16’ long pcs = 4.83 pcs of 16’ long lumber • 4.83 pcs x 5% waste = 5.07 pcs • 5.07 roundup to 6 pcs of lumber

6. Calculating stakes for footing • stakes are used to keep forms in place • assuming forms are 12’ long you use a stake every 4 feet • (total # pcs * 3)+(1 for each corner)= # of stakes • # of stakes / 24 = # of bundles • roundup to full bundles (5.66 to 6) • example • (6 pcs x 3)+(1 inside + 1 outside )= 20 stakes • 20 stakes / 24 = 0.83 bundle • 0.83 roundup to 1 bundle

7. Calculating reinforcing bars for footing • rebars are used to help strengthen concrete • come in different sizes raging from 10M to 55M in 5M increments • M = diameter of bar in millimeter • each bar has a specific weight per foot or meter • calculated in lbs or tons • length’ of ftg * number of bars * weight = lbs • lbs * waste factor = total lbs • always use longest length of footing • overlap at corners so rebar can be tied • example • 22.66’ x 3 bars x 0.587 lbs per foot = 39.9 lbs • 39.9 lbs x 5 % waste = 41.9 lbs

8. Calculating concrete footing • concrete is measured in cubic meters ( m3) • waste should be included in the calculations • care should be taken not to overlap at corners • length’ of ftg. * width’ of ftg * (depth” of ftg / 12) = f3 • f3 / 27 = y3 • y3 * 0.7646 = m3 • sub total m3 * waste factor = total m3 • roundup total m3 to ¼ m3 increments (23.6 = 23.75) • example: • 22.66’ long x 1.33’ wide x (8” depth / 12) = 19.89 f3 • 19.89 / 27 = 0.74 yd3 • 0.74 x 0.7646 = 0.57 m3 • 0.57 m3 x 5% waste = 0.60 m3 • roundup to 0.75 m3

9. Assignment • Calculate the following • linear feet of footing forms • number of 12’ pieces for footing forms • number of bundles for wood stake • number of lbs for rebars • number of cubic meters for concrete • number of pcs. for ftg. forms, rebars and concrete must include a 5% waste factor