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Deep Foundations
Helical Piles and Helical Tiebacks
For Enginners:
Typical Helical Specifications
Drilled Piers
Liquefaction Solved
Horizontal Cracks
Foundation Replacement
Resistive Piers
Underpinning Done Right
Mega Foundations
with Helical Piles
Solar Panel Arrays
with Ground Screws
Pipeline Anchors
Bridge Abutments
Post-tensioned Concrete
More Commercial Projects
Retaining Wall Basics
Retaining Wall Fortification
Solving Limited Access
Using EPS Blocks
Using W-beams
Excavation & Drilling
Road Washout Repair
Road Fortification
Hillside Stabilization
Challenging Hillside
Additions & Patios
Landslide Repair
Impact Walls
Avalon Supports
the Famous Rockettes
CASE STUDY #72 (1 of 10)

In this case study of value-added contracting, the client desired an addition behind a hillside house. The original design was for a small addition, which displeased the client and required very deep pin piles which made construction costly and impractical due to limited access.

Avalon provided the following design concept which used helical piers and helical tiebacks instead of only pin piles. The grip into the hillside provided by the lower tiebacks is transferred to the pin wall through the structural slab, restraining the top of the pin wall. This resulted in shorter pin wall piles, making the project practical and affordable. The client was allowed a larger addition.
CASE STUDY #72 (2 of 10)

Upon Avalon’s recommendation, the general contractor installed straps and cables to support the existing kitchen extension, allowing its support posts to be removed.
CASE STUDY #72 (3 of 10)

As excavation continued, the rear of the house was underpinned with 2 7/8" round shaft piers, with load transferred to the piers.

As can be seen in the image, Helical tiebacks were installed high and low, welded to the vertical pier. The upper tieback provides lateral support to keep the lifting bracket and foundation from rotating. The lower tiebacks become the lateral support, via the slab, to the top of the pin pile wall.
CASE STUDY #72 (4 of 10)

Underpinning piers in place as excavation continues.
CASE STUDY #72 (5 of 10)

Pin piles and grade beam have been poured (left side of photo) as excavation continues. Existing foundation has been marked for dowels. Excavation later completed by removing ramp from above.
CASE STUDY #72 (6 of 10)

Center gradebeam has been excavated, with center piers installed. Gradebeam and slab rebar has been set, with waterstop in place. Slab will be 8 inches thick, with Xypex for waterproofing. Avalon does its own concrete pumping, and so can better control water in the concrete mix.
CASE STUDY #72 (7 of 10)

The slab has been poured. The rebar in the wall will be extended upwards.
CASE STUDY #72 (8 of 10)

Here the walls are formed.
CASE STUDY #72 (9 of 10)

Here the walls are poured and then stripped.
CASE STUDY #72 (10 of 10)

Here is the completed foundation which allowed the happy clients an addition larger than they had originally hoped.

General Contractor:
Pro-Built Construction
Avalon installs patios on hillsides, such as this patio slab under construction adjacent to a hillside.

In this case, drilled piers were installed to support the outside edge of the patio.
New patio of stamped concrete.
Avalon Structural, Inc.
181 Ridgeview Drive
Aptos, CA 95003
(831) 479-4389 (office)
Copyright © 2015
Avalon Structural, Inc.
All Rights Reserved
CA License 677116
Classifications:  B, C-8
Avalon is a general building
contracting firm and
does not employ engineers.