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10 Easy Steps to Construct a Isolated Footing

There are various types of footing can be constructed for a building. It is structural engineer's responsibility to decide which type of foundation is to be constructed for a building.

As construction professionals, our responsibility is to properly construct footings as designed or suggested in structural drawing.

In this post I'll show you how to construct a isolated footing for a residential building. You can do this in following 10 easy steps.

10 Steps to Construct a Isolated Footing

Follow the steps below to construct a isolated footing.

1. Positioning Footing Location

Footing layout sheet of structural drawing shows dimension related to grid line to place the footing on ground. See the image below.

Mark the footing on ground as shown in the drawing.

2. Earth Excavation

Excavate a trench on earth for the footing. The size of trench should be 1' bigger in both side than the footing size. In the above image we have a footing size of 4' x 5'. For this footing you have to make a trench size of 5' x 6'. It is done for placing and removing shutter easily.

The depth of trench will depend on the earth condition or suggested in the drawing.

3. Preparing the Base

Depending on the soil condition of the base you may require to make brick-flat-soling or cement concrete at footing-base. It is also suggested in the structural drawing.

Read More:
A Checklist for Brick Flat Soling

Sometimes brick-flat-soling isn't suggested in the structural drawing. If you found the base soil isn't suitable enough to construct the footing without brick flat soling then consult with structural designer.

4. Making Form-work

Make form for the footing as specified size. You can use wooden shutter or steel shutter for this purpose. Place the form as showed in the footing layout sheet of structural drawing.

Read More:
Types of Formwork Materials

Check the dimension of form and check if it is properly placed related to grid line. Also make the form-work leakage proof.

5. Placing Reinforcement

I assume you have the required materials for the isolated footing available on the project.

Cut the steel reinforcement as required sizes and provide L-bend  as shown in the structural drawing. You can make the reinforcing net for the footing separately and place in footing position later or you can place the reinforcing bar directly on footing position and bind them there.

One important thing sometimes not shown in the drawing is that - in which direction main reinforcement of footing should be placed - in short direction or in long direction?

In footing, placing main reinforcement doesn't follow the short direction rule. It is related to position of column on footing. Read the following post to know about this.

Placing Main Reinforcement of Footing

6. Providing Cover Block

It is very important to maintain concrete clear cover ont only in footing but also in all RCC members. Provide required cover block in bottom and sides of footing to keep the reinforcing net in position.

7. Placing Column's Reinforcement

Neck column reinforcement should be placed before pouring concrete into footing. Because neck column's reinforcement sits on the bottom reinforcement of footing.

8. Pouring Concrete

Check again the footing and column are properly placed. Check the form of footing is leakage proof. If everything is perfect then move to pouring concrete.

If the concrete volume is large or if you make several footings to cast at a time then you can go for ready-mix concrete. Otherwise you can cast your footing with machine mix concrete. In that case you have to order and stacked the required concrete ingredients on the job-site before.

9. Removing Formwork

On the next day remove the form of footing. If any small honeycomb appears on footing's surface repair those properly. If checked the formwork properly major honeycomb won't appear.

If major honeycomb somehow appeared on the footing then you have to consider breaking the footing and reconstructing.

10. Back Filling

If everything is ok then fill the trench with soil and compact.

Now what? I think, you noticed I back-fill the footing's trench before constructing neck column. Don't do this. Yes. Before back filling you should construct the neck column.

Tour Turn:
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