Elevating a building by placing it on a buoyant system involves moving the structure temporarily, constructing a pit under the building, installing the buoyant system, and placing the building back over the pit. The building can then be elevated temporarily above the floodplain during flood events and lowered during normal operations. The buoyant system may be visible during normal operations, although minimally. The buoyant system can consist of buoyancy (or flotation) blocks or buoyancy tanks. A sump pump should be installed to remove water from the pit after the flood event. Generally, this solution is most effective for small, light-weight structures, such as small, wood frame structures, with limited glass and plaster.
The main advantage of elevating a building by buoyancy is that the floodwater is doing the work to raise the building. Additionally, during normal operations, the system is minimally visible.
There are several disadvantages to elevating a building by buoyancy. First, deployment of the system cannot be controlled and will be activated even during minor floods. Second, the rate at which the building rises and lowers cannot be controlled and there is the potential that the building will not remain level. Third, the buoyant system must be regularly maintained to ensure that it is functioning properly.
- Guiderails must be installed to ensure the building stays in the same position, and they must extend several feet above the ground and are, therefore, visible.
- Cleaning the pit in which the buoyant system is stored can be challenging, and debris that gets in the pit cannot be removed without jacking the house up during normal operations.
- Excavating the pit required to hold the buoyant system becomes much more difficult and expensive if there is bedrock near the ground surface.
- To make room for the pit and buoyant system, any below-grade spaces (like a crawlspace or basement) may be lost.
- The building’s utilities must be waterproofed and flexible connections must be installed.
- Before construction begins, it is important to determine if the land beneath your building has the potential to yield archaeology that is important to history or prehistory.
- Buoyant Foundation Project: buoyantfoundation.org/
- Shoal Creek Conservancy: www.shoalcreekconservancy.org/water/flood-showcase/buoyant/
- A Local Solution to a Global Flooding Problem: www.therecord.com/news-story/7140672-a-local-solution-to-a-global-flooding-problem/
- Water-Resistant Home Floats During a Flood: www.designindaba.com/articles/creative-work/water-resistant-home-floats-during-flood