Flood-Resilient House Design And Methods

Future flood damage is an important factor to consider when choosing to go for a flood-resilient house. Damage can be classified into two categories: potential damage and actual damage. The amount of water that has actually infiltrated the house determines the amount of potential damage to the house from floodwater. On the other hand, actual damage is defined as the amount of water that can be found in the structure of the house.

Flooding is widely regarded as one of the most common and destructive natural disasters that have ever occurred on a global scale, and the enormous environmental hazard posed by flooding in the Philippines is no exception. With an estimated 1,316,320 hectares, Central Luzon alone accounts for 32% of the country’s flood-prone areas. This creates a sense of urgency across the country, as intense rainfalls caused by inevitable typhoons and monsoons result in widespread flood damage, including overflowing waterways and sediment accumulation in flood plains.

While national policies aimed at preventing and mitigating flooding on a large scale appear to be the preferred long-term solution, flood-resilient measures applied to individual building construction and development are equally important. Individual developers and homeowners can make their homes and businesses more flood-resistant at their own investment and commitment with proper design.

On Flood-Resilient Designs

Understanding how floods work should be the very first step in addressing how to achieve flood resiliency in individual building construction and property development before tackling how to achieve flood resiliency in larger building construction and property development. Contrary to popular belief, dealing with floods does not require a sole focus on water. Additionally, it entails dealing with the debris, motion, and accompanying weather conditions.

Flood depths, which are then classified into three levels, are a significant factor in determining the extent of flood-related damage.

Below ground floor level

• Corroded metal components
• Huge moisture absorption for timber components, which can lead to warping
• Reduced material resistance and structural integrity
• Rot and mold
• Silt accumulation
• Structural instability due to erosion beneath foundations

Ground floor level to 0.5 meters above floor level

• Damaged internal and external doors
• Damaged wall coverings and plaster linings
• Irreparable damages on timber components
• Reduced floor insulation and debonding of screeds
• Reduced insulation due to water and silt accumulating inside cavity walls

Above 0.5 meters

• Debris impact
• Eroded ground surfaces due to high-speed hydrodynamic forces
• Structural damages
• Unstable walls due to hydrodynamic and hydrostatic loads

How Flooding Affects Building Materials

Apart from flood depths, three more factors influence the extent of damage to building materials during times of floods. They include the compounds mixed with water, the duration of immersion, and the structural details.

When building materials come into contact with water, they begin to decay and deteriorate, losing their properties and reducing the building’s overall stability in the process. However, when a sound building design is implemented, limited damage may occur during floods.

As previously stated, floodwater is made up of more than just water. For example, when water is mixed with salt, it can cause sulfate attacks on metal components. When these components (steel, for example) come into contact with water and air, they oxidize, resulting in rust. The occurrence is especially dangerous for reinforced concrete structures. When moving floodwater is involved, it can encourage dragged silt to be deposited in concealed areas of a house, which, in addition to promoting continued wetting and drying, can result in the growth of mold and wet silt.

Apart from the natural factors that influence the destructibility of a flood, another frequently overlooked factor is construction details. Due to the absence of flood-related considerations in construction details, a house or development becomes more vulnerable to water-induced damage. To begin, examples of flood-resistant construction details include minimizing cavities through which water can potentially penetrate and damage exposed building materials, while also allowing the structure to be easily cleaned and dried following a flood.

Factors To Consider In Building Flood-Resilient House

The flood-resilience of a house or structure is determined by its location. Here are five factors to consider when determining the degree to which a home should be flood-resistant:

Optimum Flood Level Height

The lower the floodwater depth of a building is, the more natural the flood-resilient measures that are implemented on it.

Water Flow Velocity On Flood Peaks

The lower the flood velocity, the more straightforward it is to design a flood-resistant structure.

Flood Frequency And Duration

The more frequent flooding events occur, the more vital and expensive flood-resilient measures become.

Flood-Resilient Structural Features

Flooding imposes both horizontal and vertical loads on the structure and substructure, making it critical to ascertain the amount of pressure exerted by these loads prior to completely flood-proofing the structure. This is especially true for residential homes, which require unique design solutions to compensate for their inherent lack of anchorage and resistance to lateral forces.

Economic Characteristics

Combining flood-proofing and flood-protection measures such as dikes is the best course of action, even more so if you intend to build your home in an area where flooding waters move quickly. Bear in mind, however, that this will not eliminate the possibility of flooding in your home completely. If your cost-benefit analysis indicates that the anticipated benefits outweigh the estimated costs, your flood-resilient measures may be considered economically justified.

Building Techniques For A Flood-Resilient House

Choosing the right building techniques is important when it comes to building a flood-resilient house. Building techniques that are designed to prevent flooding can be used to prepare the building built on top of flood-prone areas. If you are living in an area that is prone to floods then your best option would be to mitigate further potential damage. This means building higher up and choosing materials that are more resistant to rising floodwaters. These are the different methods or innovations that are more responsive to rising waters.

Dry Water or Flood-Proofing Method

The dry waterproofing method ensures that water will be kept outside of your home and away from your possessions. If you are willing to allow floodwater to come into contact with the walls of your home, make sure that they are kept water tight at all times. In order to accomplish this, you can use either a sealant or waterproof membranes.

Wet Flood-Proofing Method

In direct contrast to dry waterproofing, this solution allows water to enter while minimizing potential damage. This can be accomplished by opting for solid waterproofed concrete slabs rather than wooden floors, increasing the distance between power outlets and the finished floor line, and ensuring that fixed furniture is constructed of waterproof materials, among other measures.

Elevation Method

This is arguably the most traditional method of flood-proofing your home, particularly if you’re building along a river or the sea. While there are numerous ways to elevate your home, common suggestions include building on stilts, using concrete pylons, constructing a bank of earth, or incorporating a sacrificial parking area beneath the house.

Flood-Resilient Floating Homes

Just as the name suggests, floating homes are built atop boats – hence the name. To do this, however, you’ll need to consult an expert home builder to help you build a floating home amid a flood-prone area.

Flood Walls Method

While raising your home appears to be the most common solution, another traditional method is to build a waterproof wall. While this is an excellent protection for individual homes, it is equally effective for entire towns and villages. Additionally, to maximize the use of floodwater, you can surround these walls with landscaping and vegetation.

Costs To Flood-Resilient Houses

It is true that completely protecting your home from the damaging effects of flooding can be extremely expensive. Returning to the cost-benefit analysis we discussed earlier, both the physical and monetary efforts involved in flood-proofing your home can be considered a long-term investment, allowing your home to remain habitable even after a potentially damaging flood event has occurred.

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