Built in 1937, the Fallingwater Residence stands to this day as one of the greatest architectural achievements of Frank Lloyd Wright. Over time, the structure has endured a number of structural issues, which included cracking and deflection at the cantilever terraces. To ensure its historic value, contractors used post-tensioning systems to rehab a portion of the deteriorating elements. Post-tensioning allowed for hidden repairs in the floor cavity between the girders, making rehabilitation virtually invisible from many viewpoints. With repairs completed in 2002, the post-tensioned systems used proved to be a durable solution for the Fallingwater residence.

1. The Fallingwater Residence
Mill Run, Pennsylvania, USA
Project Abstract:
Built in 1937, the Fallingwater Residence
stands to this day as one of the greatest
architectural achievements of Frank Lloyd
Wright. Located in Mill Run, Penn., the home
caters to thousands of visitors each year.
Over time, the structure has endured a
number of structural issues, which included
cracking and deflection at the cantilever
terraces. To ensure its historic value,
contractors used post-tensioning systems to
rehab a portion of the deteriorating
elements. Post-tensioning allowed for
hidden repairs in the floor cavity between
the girders, making rehabilitation virtually
invisible from many viewpoints. With repairs
completed in 2002, the post-tensioned
systems used proved to be a durable
solution for the Fallingwater residence.

2. The Fallingwater Residence
Mill Run, Pennsylvania, USA

3. Project Overview:
Originally built in 1937, the Fallingwater
Residence in Mill Run, Penn., serves as a
lasting embrace of architecture designed
by Frank Lloyd Wright. Organic in the
nature of design, the home has inspired
American culture for more than 60 years.
Over time, the structure has endured a
number of structural issues, which
included cracking and deflection at the
cantilever terraces. Although the
cantilever girders at the main level
contain up to 16 one-inch-square bars
each, engineers found that the girders
were not capable of maintaining the
design loads.
The Fallingwater Residence
Mill Run, Pennsylvania, USA
This inadequate load caused both terraces to
sag downward towards a nearby stream.

4. The Fallingwater Residence
Mill Run, Pennsylvania, USA
Project Overview:
The Western Pennsylvania
Conservancy, owners of the property
since 1963, began planning for
rehabilitation of the deteriorating
elements in 1995. Contractors utilized
post-tensioning systems to limit the
presence of restoration to visitors of
the historical residence. Aesthetically,
post-tensioning could be hidden in the
floor cavity between the girders,
making rehabilitation virtually invisible
from many viewpoints. Four concrete
cantilever girders were used to support
the main terrace, with a concrete slab
placed
monolithically at the bottom of the girders to form
a soffit. Contractors also used multi-strand post-
tensioning of three support girders spanning in the
north-south direction. Thirteen-strand tendons
were placed on each side of two of the girders.
One 10-strand tendon was placed on the western
side of the third girder. Eight monostrand tendons
were slated for the east-west direction.

5. The Fallingwater Residence
Mill Run, Pennsylvania, USA
Project Overview:
The project was a challenge for
contractors for several reasons including
the fact that it was imperative to
preserve the historical elements of the
structure. Additionally, contractors had
to work in cold weather conditions to
complete the project within budget and
in a timely manner. With repairs
completed in 2002, the post-tensioned
systems used proved to be a success for
contractors of the Fallingwater
residence. The durability of post-
tensioned concrete will allow for the
long-term sustainability of Frank Lloyd
Wright’s iconic home.