Sai Towers pvt. ltd. working in field of road construction , building construction, road development, repair and maintenance, house keeping etc.

1. TOP DOWN CONSTRUCTION
ADVANTAGES
By
Sai Towers P Ltd.

2. Why Top Down Construction
Required
• Distance between Boundary wall of Adjacent Existing Building and
Building Line for New Building is too close and the depth of
excavation is more than 6 meter and possibility of collapse the soil
is higher during excavation.
• Using Top Down Construction more Building and Basement Area
can use. Suitable for two or more basement.
• The first base slab level slab will act in such area as a strut member
and the Retaining wall panels will not allow collapse of soil.
• Water table is too high and difficult to cast Retaining wall,
Diaphragm wall or Continuous Pile can use as a Retaining wall.

3. METHODOLOGY OF TOP DOWN
CONSTRUCTION
• Setting out for alignment of bore cast in situ of piles .
• Bore Cast in Situ Piles to be cast and dowels bar to be kept for
Retaining wall panels. The center of piles and Retaining wall panels
center line to be kept in same line. The Diameter of Piles preferred
600 mm, distance between two piles center to center preferred
3.33 meters (Suit for C/C distance of Columns), Depth of Piles to be
confirmed by Structural Consultants.
• Touching Piles can use as a Retaining wall with supporting
arrangement during Excavation.

4. • Water table is too high and difficult to cast Retaining wall, Diaphragm
wall or Continuous Pile can use as a Retaining wall.
• Instead of Column C1 to Column C8,Bore cast in Situ piles to be cast with
dowel bars for different level slab and connecting Beams, The Diameter of
Piles (suit as per Columns size), Reinforcement details (with dowels for
Retaining wall and different level slabs and Beam), Depth of Piles to be
confirmed by Structural Consultants.
• Excavation to be done around 2 meter depth and retaining wall panels to
be cast in stages with dowels bars with adjacent piles and dowel bars for
next Retaining wall panel to be kept .if soil between piles collapsed soil
nails with wire mesh to be kept on earth side to retain the same. Retaining
wall panels to be cast with dowels up to the first base slab bottom.

5. • Dressing and compaction of soil to be done for PCC bed for casting
of first base slab. 50mm PCC (M15 Grade) to be done, the top levels
of PCC to be keep the base slab level bottom. For beams excavation
to be done in same alignment and dimensions as required and PCC
or brick work to be done as per beam dimensions in Vertical face.
• After PCC 3mm ply to be laid on PCC Surface and PVC sheet to be
nailed with PCC surface so surface of PCC and Surface of Slab
Concrete will separate. 7. Reinforcement to be completed as per
drawings, for beams dowel bar to be used from Cast in Situ Piles.
Dowel bars to be keep for adjacent slabs for Bottom Up
Construction.

6. • Concreting of Slab and Beam to be completed.
• After 14 days of Concreting, PCC below slab to be break/removed
excavation to be continued and retaining wall panels to be cast. Till
final level of excavation.
• Waterproofing to be done and base slab to be cast with dowels
from Cast in Situ Piles.
• Jacketing of Columns to be done if required
If any query please mail – saitowers2000@gmail.com
or visit - sai-towers.com