A custom high end home was built on a very steep hillside lot overlooking Lake Washington near Seattle. The owner of this home owns an excavation/gravel business. He has all of the heavy equipment and free soil he could ever want, yet he chose to backfill three foundation walls with geofoam. This project was originally designed with a compacted soil backfilled MSE wall that would have to be trucked down 95′, through a country club and from the top of the hill. The amount of concrete, reinforcement, tie backs and forming costs that were removed from the foundation design more than paid for the geofoam and reduced the total weight of the import fill material by over 2 million pounds.
Benefits that lead to overall project cost savings by using geofoam as an alternative to traditional soil fill:
- Geofoam is easily installed and the lightweight nature of geofoam allows it to be maneuvered by hand and used on projects with tight construction access where the use of larger mechanical equipment may not be feasible.
- Shotcrete, Gunite, or soil can be placed directly against geofoam eliminating the need for expensive forming.
- Construction traffic and import costs are minimized, as 1 flatbed truck of geofoam is equivalent to approximately 12 dump truck loads of traditional fill.
- Congestion on the roads or road closures leading in and out of a project site is minimized.
- The construction time of a project is reduced as several feet of geofoam can be placed in a fraction of the time that it would take to the place and compact traditional soil fill in the required 8 to 12-inch lifts. As an added incentive, geofoam does not require compaction testing like tradition fill.
- Decreased maintenance costs as a result of less settlement issues from the low density geofoam.
- Tight construction scheduling can easily be maintained using geofoam as it can be installed during any type of weather or site conditions.
- Geofoam is extremely eco-friendly and geofoam blocks can be re-used in other projects or be recycled.