Things to Check Before Concreting Footings

Quick Summary

Before starting concreting, it is essential to inspect both formwork and reinforcement for accuracy and safety.
The article first explains how to check formwork for alignment, level, support, and leakage prevention.
It highlights key footing formwork checks like centering, size, cleanliness, and sealing of joints.
Reinforcement checks include bar cleaning, proper tying, spacing, cover thickness, and steel grade verification.
It also stresses ensuring correct positioning, cover blocks, and column bar extensions into the footing.
Safety practices like stable excavation, shoring, and approval before concreting are emphasised.
Following these checks ensures high-quality and long-lasting foundation work.

General practice is to check when the footings are ready for concreting i.e. reinforcement fully tied up but ideal practice would be to check it in two phases i.e.

1. First check formwork before you allow placing of reinforcement. This is necessary as certain formwork defect can’t be corrected or are difficult to correct after reinforcement is placed in position.

2. Checking reinforcement.

Hence as a standard engineering practice one should check first the formwork before reinforcement is placed or tied.

Also Read: Things to Check Before Concerting Column

Points to Check Before Concreting Footings

1. Centering and Shuttering / Formwork

Even before commencing the shuttering & centering / formwork for footing, the following points need to be checked.

Check the center lines / margin from boundary etc. from reference column/bench mark pillar, boundary distance from roads and of course orientation with respect to North.
Ensure that the foundation rest at a designed depth as per drawing.
Size of formwork box should be as per drawing and it should be made up of approved materials.
The formwork should be dry and shall be cleaned carefully before applying mould release agent. The same type of release agent should be used throughout on similar formwork materials.
The surface of formwork should be even and thinly coated with mould release agent.
The mould release agent should not come in contact with reinforcement or the hardened concrete.
The height of shuttering should be same as that of the height of pedestal and joint should be sealed to prevent any leakage of cement slurry.
Footing box should be supported properly, so that position of footing box should not get changed during concreting.
Centre of the footing should be marked with help of nail on planks or footing box.
Foundations shuttering should be sound in dry or even rainy conditions or even when ground water is there.
Take approval for shuttering from Engineer-in-charge or supervisor before tying reinforcement.
See that there is no earth collection on P.C.C. before tying reinforcement.
If foundation depth is more, ensure that the excavated earth does not slide or fall till it is refilled. Do proper shoring and shuttering. Ensure proper ladder etc to go in the pit as well as for coming out. Also, ensure safety of labour’s working.

2. Reinforcement

The reinforcement steel should be free of any loose scale, rust, mud, or oil.
Reinforcement of footing mesh (jali) should be cut as per bar bending schedule.
Footing mesh should be prepared by tying the bars. Each and every junctions should be tied with binding wire.
The bend (‘ L ‘) in mesh should be 90° and bar is required to be upward.
The center of the footing mesh should be matched with the center of the footing.
Check the gauge of binding wire.
Check lap length provided for lapping of steel reinforcement. However, for footing laps should not be allowed.
Check that spacers are provided to achieve concrete cover. It should not be less than 50 mm.
The minimum thickness of cover to main reinforcement should not be less than 50 mm for surface in contact with earth face and not less than 40 mm for external exposed face.

However, where the concrete is in direct contact with the soil, for example when P.C.C is not used at bottom of footing, it is usual to specify a cover of 75 mm. This allows for the uneven surface of the excavation.
In case of raft foundation, whether resting directly on soil or on lean concrete, the cover for the reinforcement should not be less than 75 mm.

The diameter of main reinforcing bars should be not less than 10 mm.
The reinforcement steel grade, size, cover, spacing, and splicing should be as per the approved plan.
When a column terminates into a footing or mesh, special confining reinforcement shall extend at least 300 mm into the footing or mesh or as per drawing.
A minimum of four bars should be provided in column.
A minimum three stirrups (rings) should be provided when column terminates into footing.

Conclusion

Checking the formwork and reinforcement before concreting footings is vital to ensure accuracy, safety, and durability. By following the recommended inspection steps, engineers can avoid structural defects and guarantee a strong, stable foundation.

Also Read: What is Reinforced Concrete Framed Structure?