Mitigating Flood Risk in Buildings
Mitigating #flood risk plays a key role in #designing new #buildings and #retrofitting existing ones, especially since one in six properties in the #UK is at risk of #flooding. With this figure expecting to rise in the context of the current climate changes, it is important to understand what steps can be taken in the design process to manage and reduce the effects of the possible floods.
Designing a building requires a good understanding of the site and its immediate context to identify any constraints and their potentialdesign implications. Therefore, it is critical to establish early whether the site is in a flood-prone area, by conducting an initial appraisal right at the beginning of a project, during the strategic definition stage (RIBA Stage 0). The government website is a reliable source of information for obtaining flood risk information for planning in #England, as well as providing easy to use #web maps to assist with checking the flood #levels for a specific #site and whether a flood risk #assessment (#FRA) is required.
Designing a building requires a good understanding of the site and its immediate context to identify any constraints and their potential design implications.
Such an assessment not only outlines the potential for the site to be impacted by flooding, but it also presents measures that can be incorporated into the proposed development to reduce the identified risks. Usually, such #measures comprise of both #flood resistance and flood resilience #strategies, having the former in place to keep the water out of the building and the latter to ensure the #dwelling is capable to recover quickly after a flooding event.
Panels slotted into permanently-fixed channels
Flood resistance #structures, such as sturdy #masonry walls and flood gates are some of the most common methods when it comes to restricting water from protruding into the building, followed by precast concrete flood defence walls and #metal barriers. These are to be built to certain heights to resist the predicted water levels and pressure outlined in the FRA.
If part of an external #cavity wall, the bricks need to have low-water absorption properties and be fitted with a high-level damp-proof course in line with the FRA’s recommendations, while any unavoidable low-level weepholes or vents should be covered or sealed to prevent any water ingress. The use of #materials and #construction #techniques should not only prevent the water from getting in, but they should be chosen so that the building can withstand the structural and material damage caused by flood water and contribute to a speedy restoration so the building can become habitable again.
Flood #barriers are usually the go-to #solution when it comes to #blocking #flood #water from getting in. In contrast to brick or #precast walls, these are temporary solutions to block the access points, such as gates or doors openings. Although they are quick and easy to install, they should be carefully considered during the #design #process, to ensure they are fully #coordinated with the rest of the design, so they can #perform as expected.
Flood barriers installed in front of an access point
Indoor opening doors, deep reveals and flush finishes are some of the few design considerations that need to be taken on board to future proof the installation of the barriers Some systems may require #permanently-fixed side #channels within the opening to be protected, so the depth of the reveal should be suitable to accommodate the thickness of the channels. Such channels can be observed in the image below, where these are installed to a riverside property to withstand any tidal water caused by the #raising levels of the #River #Thames.
Raised entrance with fixed channels to accommodate the flood barriers
When a channel is not required, the workmanship of the reveal and the wall finish is to be observed, since the panels cannot seal against irregular surfaces. Likewise, the floor barriers need to fully seal against the floor, so it is important to check their compatibility with the floor finishes, more so since certain types of paving slabs are not suitable to use in conjunction with specific flood gates.
Regardless of the flood gate type, their performance is dependent on a flood #warning #subscription and a good #management system, so if any guidance is issued, the flood barriers can be quickly deployed. Nevertheless, the manufacturers should be able to advise on a fully compatible system with the proposed design and in accordance with the flood #mitigation #strategy.
So, have you spotted any flood resistance measures during your daily stroll or have you employed any in your design? Let me know your thoughts in the comments box below.
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