Tulane University’s Alumni House was built nearly 75 years ago. The colonial red brick property, which boasts two floors plus an attic, was home to the university’s Office of Alumni Affairs. Unfortunately, it had to be shuttered nearly 10 years ago after being damaged by flood waters resulting from Hurricane Katrina. Abry Brothers and 1800 Foundation Repair – New Orleans’ oldest shoring and elevating contractor – stepped in and saved the historic property by repairing the damage to the foundation. How? By elevating it.
Flood elevation techniques
According to the Federal Emergency Management Agency’s (FEMA) and Abry Brothers Foundation Repair, elevating a property is one of the best ways to protect it from floods and other natural disasters. This holds true in flood-prone regions such as Louisiana where Tulane University is located. According to the National Flood Insurance Program, flood damage is significantly more common than fire damage, particularly in high-risk areas. There are several elevation techniques available, but they all tend to do one of two things:
- lift a house and then build a new foundation underneath it, or
- leave the foundation intact and add a new floor.
Source: FEMA
Elevating a property may sound simple, but it requires the help of experts. Historic properties in particular are notorious for questionable foundations thanks to faulty footings, inaccurate load calculations and substandard mortar making on-site expertise crucial. One of the most popular elevation techniques call for houses to be separated from their foundations. Hydraulic jacks are used to raise the house, which is held with the help of temporary supports so that either a new or extended foundation can be built beneath it.
This technique is particularly effective for buildings constructed on basement, crawlspace or open foundations. Lifting up a masonry home, however, is more challenging than lifting a wood frame building due to its weight and design. An alternative is leaving these buildings attached to the slab and elevating both. A new foundation is then constructed underneath the slab.
Sometimes, leaving a property’s original foundation untouched is the best alternative, especially for masonry houses on slab-on-grade foundations (see the diagram below to understand how the slab can be supported). One relatively simple option is to leave the existing lower enclosed area untouched (i.e. the level containing the slab floor) and moving the living space to a new floor by either using an existing upper level or constructing a new one. The abandoned lower floor be used for parking, storage and to access the house. Alternately, the project could be extended to removing the roof, extending the walls of the house, replacing the roof with a new one and then constructing a living area that’s elevated.
Source: FEMA
Base Flood Elevation
Regardless of the elevation method, it’s important to meet base flood elevation (BFE) standards. They can be found on flood profiles and Flood Insurance Rate Maps. Properties that have seen significant damage or are going through large-scale renovations need to comply with the law and have their lowest floor elevated to or above the BFE. While this rule may not apply for small-scale improvements, it’s still recommended to do so. Properties that do not comply with BFEs are more susceptible to flooding and generally will not see a decrease in their flood insurance rate.
So how much should you elevate? Generally, elevating three to four feet above the existing ground level will not alter the appearance of the house. However, if more than four feet is recommended, then consider a full story elevation. That way the space below can be used for storage and building access.
Using the existing foundation
The most economical solution to addressing flood risks is to use the existing foundation. However, a contractor should evaluate your property’s foundation and make sure it’s strong enough to support the loads imposed by the elevation, along with the loads that may result from flooding. Whichever technique is selected, it should allow the building to withstand the impact of at least three things: hydrostatic pressure, hydrodynamic pressure and debris.
Another factor to consider is the access point. Doors that were located at ground level can no longer be used, so a staircase, elevator or ramp must be integrated into the property. This tends to be one of the main objections to elevating a house. But with the help of professionals, the property can still maintain its charm and character. The photo below shows the new ramp from the elevated Tulane Alumni House.
Source: Tulane University
So if you are responsible for repairing or maintaining a foundation in a flood-prone region, such as Louisiana and Florida, elevating the property may be the best alternative. With the help of a professional foundation repair contractor such as 1800 Foundation and Abry Brothers Foundation Repair, you could potentially decrease your insurance and more importantly, protect your property.