Things To Do Before Excavating The Foundation

Before excavating the foundation all top soil must be removed to one side to be used at a later time.

And then we must mark the corners of the house.

You can have a surveyor mark your corners and the proper set backs, or you can do it yourself. If you decide to do this yourself, before excavation begins,make sure you check local codes for minimum set back and side yard requirements.

After I had determined the location of my house on the lot, I used an arrangement of batter boards and lines to maintain grades and keep my work true.

First,I placed small stakes to mark each corner. These were squared by measuring the diagonals...when the diagonals are equal, the corners are square. Nails were then driven into the top of the stakes to mark the exact corners.

A graphic showing hoe to locate the corners before excavating the foundation

Another method of squaring the corners is to measure along one side a distance in three foot units and along the other side the same number of four foot units. The diagonal will have the same number of five foot units when the corner is square.

Method of squaring a corner before excavating the foundation

To make the batter board arrangement I drove three 2x4 stakes in each corner to form a 90 degree angle. One by six(1x6) boards were then leveled and nailed to each stake.

The 2x4 stakes should be set back from the corners at least four feet so they will be out of the way during excavating the foundation.

A excavator should be able to reach over these boards without hitting them... but accidents do happen.

I used a lazier level and a tripod to level the 1x6 boards. By placing this same elevation on a nearby tree... I had a reference point in case the batter boards got shifted when excavating.

With the aid of a plumb bob I placed lines from corner to corner to line up exactly with the nails in the small corner stakes .When the lines were exact, their location on the batter boards were marked so they could be taken down and replaced at a later time.

Not all houses are rectangular or square in shape, but this method will still work. My house was a combination of three rectangular shapes.

Now excavating the foundation can start. The depth of excavation will depend on the foundation wall,street elevation, drains and elevation of neighboring houses.

The finish grade should be at least eight inches below any wooden parts of the house.. such as the siding.

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