PRECAUTIONS TO CONSTRUCT NEW FOUNDATION NEAR OLD STRUCTURES

When you are constructing a new foundations near to the old building at that time because of vibrations and other forces which generate during construction can effect the stability of the existing structures.

The depth of the foundation which is going too construct and the Foundation distances between the two buildings (old and New) is very important and necessary to reduce the failures. In order to eliminate the chances of  any damage to the old structure, following precautions should be taken:

IMPORTANT POINTS:

1. The clear horizontal distance between adjacent faces of old and new foundations should be at least to the larger of the widths of foundations.

2. If the foundation of new structure is to be laid touching the old structure, its foundation should not be carried to the depth greater than the depth of old foundation.

If however, new foundation has to be carried for large depth, the old structure should be adequately protected by giving lateral support to it and also by giving suitable support of the foundation.

3. For deciding the depth of new foundation up to which it can be excavated without affecting the old structure, draw an inclined line from outer bottom-most edge of old foundation.

The depth of new foundation should not cut this line. Inclination of this line with horizontal for soft soils is kept 30° and for average soils 45°.