This document discusses construction techniques for buildings in flood-prone areas. It describes various floodproofing methods like dry floodproofing, wet floodproofing, elevation of structures, and anchoring systems. Dry floodproofing aims to seal the building from floodwaters while wet floodproofing allows floodwaters inside but uses flood-resistant materials. Elevating structures raises them above flood levels. Anchoring systems secure buildings to their foundations to prevent movement during floods. The document also discusses foundation requirements and types like pile foundations for withstanding flooding and coastal hazards.

1. CONSTRUCTION TECHNIQUES IN
FLOOD PRONE AREAS
- SAMHITHA G PRASAD
- SANIYA MUKTHAR
- SANJANA SHET
- SANJAY BK
- SANJAY SURESH
- HIMAJA
- SHARAD KAPOOR

2. INTRODUCTION
RESILIENT CONSTRUCTION HAS BEEN IN PLACE FOR CENTURIES, BUT ONLY RELATIVELY RECENTLY HAS
IT BEEN USED AS A SYSTEMATIC COMPONENT OF AN INTEGRATED FLOOD RISK MANAGEMENT
STRATEGY. RESILIENT BUILDINGS ARE DESIGNED AND CONSTRUCTED IN SUCH A WAY TO AVOID,
PREVENT, OR REDUCE THE DAMAGE CAUSED WHEN FLOODING TAKES PLACE. THEY CAN PLAY AN
IMPORTANT PART IN FLOOD RISK MANAGEMENT STRATEGY BY REDUCING DAMAGE AND,
IMPORTANTLY, SPEEDING UP THE RECOVERY PROCESS.

3. DESIGN CONSIDERATIONS FOR FLOOD RELIEF
6 WAYS TO FLOOD PROOF
UNEXPECTED AND SUDDEN STORMS CAN CAUSE SERIOUS FLOOD DAMAGE TO YOUR PROPERTY AND POSSESSIONS. PROPERTY
OWNERS WHO TAKE STEPS TO RETROFIT THEIR HOME OR BUSINESS IN ANTICIPATION OF UNCERTAIN WEATHER, COME OUT
AHEAD.
• RELOCATION- MOVING YOUR HOME OR STRUCTURE OUT OF THE FLOODPLAIN TO HIGHER GROUND WHERE IT WILL NOT BE
EXPOSED TO FLOODING.
• DEMOLITION- TEARING DOWN YOUR DAMAGED STRUCTURE AND EITHER REBUILDING ON THE SAME PROPERTY OUTSIDE THE
FLOODPLAIN OR BUYING A BUILDING OR HOME/BUSINESS ELSEWHERE.
• DRY FLOODPROOFING- SEALING YOUR STRUCTURE TO PREVENT FLOODWATERS FROM ENTERING.
• WET FLOODPROOFING- MAKING UNINHABITED PORTIONS OF YOUR STRUCTURE RESISTANT TO FLOOD DAMAGE BY ALLOWING
WATER TO ENTER DURING FLOODING.
• FLOODWALLS- BUILDING A WALL AROUND YOUR STRUCTURE TO HOLD BACK FLOODWATERS.
• ELEVATION- ELEVATION OF THE STRUCTURE IS PERMITTED AND REQUIRED WHEN AN EXISTING STRUCTURE IN THE
FLOODPLAIN IS SUBSTANTIALLY DAMAGED OR SUBSTANTIALLY IMPROVED. ELEVATION IS RAISING YOUR
HOME/STRUCTURE SO THAT THE LOWEST FLOOR IS 2 FEET ABOVE THE FLOOD LEVEL.

4. FLOOD PROOFING
-FLOODPROOFING IS THE PROCESS OF MAKING A BUILDING RESISTANT TO FLOOD DAMAGE, EITHER BY TAKING THE
BUILDING OUT OF CONTACT WITH FLOODWATERS OR BY MAKING THE BUILDING RESISTANT TO ANY POTENTIAL DAMAGE
RESULTING FROM CONTACT WITH FLOODWATERS. FLOODPROOFING CAN BE SUBDIVIDED INTO SEVERAL CATEGORIES:
• DRY-FLOODPROOFING REQUIRES USE OF SPECIAL SEALANTS, COATINGS, COMPONENTS AND EQUIPMENT TO RENDER
THE LOWER PORTION OF A BUILDING WATERTIGHT AND SUBSTANTIALLY IMPERMEABLE TO THE PASSAGE OF WATER.
• WET-FLOODPROOFING ALLOWS THE UNINHABITED LOWER PORTION OF A BUILDING TO FLOOD, BUT USES MATERIALS
THAT WILL NOT BE DAMAGED BY FLOODING.
• ACTIVE FLOODPROOFING, SOMETIMES KNOWN AS CONTINGENT (PARTIAL) OR EMERGENCY (TEMPORARY)
FLOODPROOFING, REQUIRES HUMAN INTERVENTION TO IMPLEMENT ACTIONS THAT WILL PROTECT A BUILDING AND
ITS CONTENTS FROM FLOODING. SUCCESSFUL USE OF THIS TECHNIQUE REQUIRES AMPLE WARNING TIME TO MOBILIZE
PEOPLE AND EQUIPMENT AND FLOODPROOFING MATERIALS.
• PASSIVE FLOODPROOFING, SOMETIMES REFERRED TO AS PERMANENT FLOODPROOFING, REQUIRES NO HUMAN
INTERVENTION—THE BUILDING (AND/OR ITS IMMEDIATE SURROUNDINGS) IS DESIGNED AND CONSTRUCTED TO BE
FLOODPROOF WITHOUT HUMAN INTERVENTION.

5. DRY FLOODPROOFING WET FLOODPROOFING
WET FLOOD-PROOFING REDUCES DAMAGE FROM FLOODING IN THREE WAYS; (1) ALLOWING FLOOD WATERS TO EASILY ENTER AND
EXIT A STRUCTURE IN ORDER TO MINIMIZE STRUCTURAL DAMAGE; (2) USE OF FLOOD DAMAGE RESISTANT MATERIALS; AND (3)
ELEVATING IMPORTANT UTILITIES. ON THE OTHER HAND, DRY FLOOD-PROOFING IS THE PRACTICE OF MAKING A BUILDING
WATERTIGHT OR SUBSTANTIALLY IMPERMEABLE TO FLOODWATERS UP TO THE EXPECTED FLOOD HEIGHT.
A DRY FLOOD-PROOFED STRUCTURE IS MADE WATERTIGHT BELOW THE EXPECTED FLOOD LEVEL IN ORDER TO PREVENT
FLOODWATERS FROM ENTERING IN THE FIRST PLACE. MAKING THE STRUCTURE WATERTIGHT REQUIRES SEALING THE WALLS WITH
WATERPROOF COATINGS, IMPERMEABLE MEMBRANES, OR A SUPPLEMENTAL LAYER OF MASONRY OR CONCRETE, INSTALLING
WATERTIGHT SHIELDS ON OPENINGS AND FITTING MEASURES TO PREVENT SEWER BACKUP.

6. -EXAMPLES OF FLOODPROOFING METHODS ARE SHOWN IN THE TABLE BELOW.
EXAMPLES OF FLOODPROOFING METHODS FOR BUILDINGS
DRY WET
active •temporary flood shields or doors (on
building openings)
•temporary gates or panels
(floodwalls)
•emergency sand bagging
•temporary relocation of vulnerable
contents and equipment prior to a
flood, in conjunction with use of flood-
resistant materials for the building
passive •waterproof sealants and coatings on
walls and floors
•permanently installed, automatic
flood shields and doors
•installation of backflow prevention
valves and sump pumps
•use of flood-resistant materials
•installation of flood vents to permit
automatic equalization of water levels
•elevation of vulnerable equipment
above DFE Level (Design Flood
Elevation).

7. DRY FLOODPROOFING-
SEALANTS, FLOOD SHIELDS AND VALVES
Temporary Flood Panel, and Permanent Flood Doors and Gates
Temporary Flood Shield Held in Place by Permanent Metal Track
Flood shields, panels, doors and gates are typically used to close medium to large openings in building walls. They can
be temporary closures that are installed only when a flood threatens, or they can be permanent features that are
closed manually or automatically.
Backflow Prevention Valve
Backflow valves are often installed to prevent drains and sewers
from backing up into a building, and are an important component
of floodproofing.

8. WET FLOOD PROOFING-
FLOOD OPENINGS
Unless dry-floodproofed, enclosed areas below the DFE must be equipped with flood openings capable of equalizing water levels
and hydrostatic loads.
Typical Flood Opening Covers
LEVEES AND FLOODWALLS
Levees and floodwalls are barriers constructed away from a building as a means of preventing floodwaters from reaching the
building. Permanent barriers are typically constructed of earth, concrete or metal. Temporary barriers are typically installed
using sand bags or water-filled tubes.
Floodwall Cross-Section of Typical 3–ft High Levee and 6–ft High
Levee, Showing the Difference in the Levee Width

9. ELEVATION OF STRUCTURES
 THE BASE FLOOD ELEVATION (BFE) IS THE CALCULATED WATER HEIGHT FOR THE FLOOD THAT HAS A 1% PROBABILITY OF BEING EQUALED OR EXCEEDED
IN ANY GIVEN YEAR (THE 100-YEAR FLOOD).
 ELEVATION IS THE PREFERRED METHOD OF PROTECTING NON-RESIDENTIAL BUILDINGS FROM FLOOD DAMAGE. IN NON-COASTAL FLOODPLAINS, THIS
REQUIRES LOCATION OF THE LOWEST FLOOR AT OR ABOVE THE FLOOD PROTECTION LEVEL. A BASEMENT THAT IS BELOW GRADE ON ALL SIDES IS
PROHIBITED.
• AN UNFINISHED, FLOOD-RESISTANT, ENCLOSED AREA BELOW THE LOWEST FLOOR CAN BE PERMITTED IF IT IS USABLE SOLELY FOR
VEHICLE PARKING, BUILDING ACCESS, OR LIMITED STORAGE.
 NON-RESIDENTIAL STRUCTURES ARE PERMITTED TO HAVE LOWEST FLOOR BELOW DESIGNED FLOOD PROVIDED THAT THEY MEET
REQUIREMENTS OF DRY FLOOD PROOFING.
 THE DRY FLOOD PROOFING IS A COMBINATION OF MEASURES THAT MAKES STRUCTURES WATERPROOFING.
 ELEVATION ON PROPERLY COMPACTED FILL
 ELEVATION ON PILES, POSTS, PIERS, OR COLUMN
 ELEVATION ON WALLS OR A CRAWL SPACE.

10. FOUNDATION REQUIREMENTS:
• A FLOOD IS AN OVERFLOW OF WATER FROM THE NEAR BY WATER BODIES,
THAT SUBMERGES LAND THAT IS USUALLY DRY.
• DIFFERENT FLOOD ZONES- ZONE A- HIGH RISK AREAS; ZONE B AND X- AREAS
OF MODERATE FLOOD HAZARDS; ZONE C- AREAS OF MINIMAL RISK; ZONE V-
HIGH RISK COASTAL AREAS.
• THE FOUNDATIONS SHOULD HAVE ADEQUATE CAPACITY TO RESIST
FLOTATION, COLLAPSE, AND PERMANENT LATERAL MOVEMENT UNDER
CRITICAL LOAD COMBINATIONS.
• THE FOUNDATION DESIGN OF FLOOD RESISTANT STRUCTURES SHOULD
DEPEND ON THE GEOTECHNICAL CHARACTERISTICS OF SOIL AND STRATA
BENEATH THE FOUNDATION AND ON THE SOIL FOUNDATION INTERACTION.

11. • FOUNDATION DEPTH: THE FOUNDATION MUST BE DEEP ENOUGH OR,
WITH THE BUILDING, BE SUFFICIENTLY HEAVY TO RESIST THE UPLIFT AND
OVERTURNING DUE TO COMPRESSIVE LOADS.
• DEPTH IS NEEDED FOR FRICTION PILES; WEIGHT IS NEEDED FOR
SHALLOWER, FOOTING-BASED FOUNDATIONS USED FOR COLUMNS OR
PIERS.
• THUS, THE LOAD ON THE FOUNDATION MUST NOT EXCEED THE
ALLOWABLE SOIL BEARING CAPACITY. FOUNDATION SYSTEMS (MATERIAL,
SIZE AND STRENGTH) WILL VARY BASED ON THE SOILS AT THE SITE AND
THE LOAD THE PILE MUST CARRY TO THE SOIL.
• FOUNDATIONS IN COASTAL AREAS MUST ELEVATE BUILDINGS ABOVE THE
BASE FLOOD ELEVATION (BFE), WHILE WITHSTANDING FLOOD FORCES,
HIGH WINDS, SCOUR AND EROSION, AND FLOATING DEBRIS.
• DEEPLY EMBEDDED PILE OR COLUMN FOUNDATIONS ARE REQUIRED FOR
MANY COASTAL AREAS.

12. • TYPES OF FOUNDATIONS PROHIBITTED IN ZONE V
AND A ARE- CRAWLSPACE, SLAB ON GRADE,
STEMWALLS, SOLID FOUNDATION WALLS, AS THEY
ARE SUSCEPTIBLE TO EROSION WHEN THE
FOOTING DEPTH IS INADEQUATE TO PREVENT
UNDERMINING.
• PIER (COLUMN) – PIER FOUNDATIONS ARE
RECOMMENDED FOR A ZONES WHERE EROSION
POTENTIAL AND FLOOD FORCES ARE SMALL. THIS
OPEN FOUNDATION IS COMMONLY
CONSTRUCTED WITH REINFORCED AND GROUTED
MASONRY UNITS ATOP A CONCRETE FOOTING.
YET, SHALLOW PIER FOUNDATIONS ARE
EXTREMELY VULNERABLE TO EROSION AND
OVERTURNING IF THE FOOTING DEPTH AND SIZE
ARE INADEQUATE.

13. • CONCRETE FOUNDATIONS - PREFERRED AS THEY ARE
WATER RESILIENT, WATERPROOF AND PROVIDES BARRIER
TO WATER ENTRY INTO THE WALL CAVITY.
• PILE – PILE FOUNDATIONS ARE RECOMMENDED FOR V
ZONES AND MANY A ZONES IN COASTAL AREAS. THESE
OPEN, DEEP FOUNDATIONS ARE CONSTRUCTED WITH
SQUARE OR ROUND, WOOD, CONCRETE, OR STEEL PILES,
DRIVEN OR JETTED INTO THE GROUND, OR SET INTO
AUGERED HOLES.
• CRITICAL ASPECTS OF A PILE FOUNDATION INCLUDE THE
PILE SIZE, INSTALLATION METHOD AND EMBEDMENT
DEPTH, BRACING, AND THE CONNECTIONS TO THE
ELEVATED STRUCTURE. PILE FOUNDATIONS WITH
INADEQUATE EMBEDMENT WILL LEAD TO BUILDING
COLLAPSE. INADEQUATELY SIZED PILES ARE VULNERABLE
TO BREAKAGE BY WAVES AND DEBRIS.

14. Anchorage and Connections
• Anchorages and connections in the structures need to be designed and executed to withstand the influence
of vertical loads, uplift forces, and lateral loads.
• Beams shall be connected to piles, columns, piers, and foundation walls adequately using suitable means
such as bolts and welds.
• Sufficient anchorages need to be installed for storage tanks, sealed conduits and pipes, and other structures
that may suffer from lateral movement and floatation during design flood condition.
• Wet flood-proofing measures typically include structural measures, such as properly anchoring structures
against flood flows, using flood resistant materials below the expected flood depth, protection of mechanical
and utility equipment and use of openings or breakaway walls to allow passage of flood waters without
causing major structural damage

15. The numeral 1 designates a building which may be
of prefabricated construction, the same comprising
side walls 2 and a floor3 supported by joists 4, the
ends of which rest on the foundation walls 5. The
walls 5 are connected with a floor 6 as shown. A
box-like structure 7 is seated on the floor 6. The
sides 8 of the structure 7 are spaced from the walls
5 to enable free movement of the structure 7 within
the foundation. A light metal frame member 9 is
secured to the top of the structure 7 and to the
joists 4 of the house structure as shown at 10, thus
preventing relative movement of the structure 7 and
the house structure. Air tanks 11 are positioned in
the structure 7, and a separator 12 positioned
between the tanks 11 prevents damage to the tanks
by movement in the structure 7.
A frame 16 of any desired cross-section is
embedded in the foundation wall 5.
Guide posts 17, in the form of rods or pipes, are
threaded at 18 to the frames 16, the guide posts 17
extending upwardly through the floor and between
the inner and outer parts of the wall 2 as shown.
To provide against breakage of the guide rods 17,
should the building sway after being subjected to
flood conditions, flexible connections 19 are
provided on the guide posts 17. The connections
comprise tightly coiled spring sections 20 welded or
otherwise secured to the adjacent ends of two parts
of the guide posts 17.

16. BUOYANT BUILDING FOUNDATION: Anchorage System for Flood Resilience in Buildings
• An anchor system for a structure which experiences periodic buoyancy situations.
• The anchor system has a member connected at one end to a foundation and the other end to the buoyant
structure.
• The member restricts movement of the buoyant structure in the transverse and longitudinal directions.
• The system allows the buoyant structure to move vertically between an upper and lower limit.

17. • Anchorage for fuel tanks- above and below the ground

18. ANCHORING SYSTEM
For the most part, housing foundations are designed with a perimeter foundation wall having either a strip footing or a
basement slab. On a rare occasion, the building will be supported on drill piers or in some cases concrete caissons. At the top
of the perimeter foundation wall is a stud wall which has usually a plurality of equally spaced anchor bolts placed about the
entire foundation encased within the foundation wall. The anchor bolts extend out of the foundation wall a predetermined
distance to accept the bottom plate of the stud wall. The bottom plate is usually pressure treated to avoid water rot and is
usually either a 2×4 or a 2×6 laid flat.
• The anchor bolts are designed to keep the house from separating from the foundation.
• local and regional building codes require that the anchor bolts be spaced a certain distance apart to provide for adequate
building tie downs to the foundation.

19. Amphibious house can also be called floating house and
broadly classified into two types:
(i) Boat type and (ii) Lift type
Boat type: This type of floating house is free to move
in both the direction i.e. in vertical direction as well as
in horizontal direction. The floor of the house should be
water tight so the water does not enter from the base.
The house is provided with some anchor system for
stopping the house to dislocate with the flow of water
from its original position.
Lift type: In the case of lift type, the house is free to
move in only vertical direction in a controlled way
along with the rising water level in flood type situation.
The house is restrained to move in horizontal direction
by guiding columns at the corners. The house remain on
ground surface until the flood water starts lifting it up
by buoyant forces. Both the houses can be provided
with a suitable base to be supported on and to provide
sufficient buoyant forces to initialize the movement.
The foundation used in these houses can be termed as
buoyant foundation. Underside of the house buoyancy
blocks is provided. Buoyancy blocks lift the house in
case of flood and can be made of recycled, recapped

20. MECHANICAL, ELECTRICAL AND PLUMBING SYSTEMS(MEP)
• STRUCTURES IN FLOOD PRONE AREAS SHOULD BE DESIGNED AND CONSTRUCTED BY METHOD AND PRACTICES THAT
MINIMIZE OR ELIMINATE FLOOD DAMAGE TO ELECTRICAL, HEATING, VENTILATION, AIR CONDITIONING, PLUMBING AND
OTHER BUILDING UTILITY SYSTEMS. IN V AND A ZONES, AND IN RESIDENTIAL AND COMMERCIAL PROPERTIES THAT ARE
NOT DRY FLOODPROOFED MUST BE PLACES ABOVE THE DFE(DESIGN FLOOD ELEVATION) AND WHERE EVER POSSIBLE
LOCATED ON UPPER FLOORS OR ATTICS.
• THE BEST WAY TO PROTECT MEP SYSTEM IS LOCATION IN ACCESSIBLE LOCATIONS ABOVE DFE.
• MEP SYSTEM COMPONENTS LOCATED BELOW THE DFE SUCH AS WATER METERS OR UNDERGROUND FUEL TANKS, MUST
BE PROTECTED BY WATER TIGHT ENCLOSURES, PROTECTIVE UTILITY SHAFTS AND ANCHORING.
• IF LOCATION OR RELOCATION TO UPPER LEVELS IS NOT AN AVAILABLE OPTION- SUCH AS PROJECTS INVOLVING FLOOD
MITIGATION AND UPGRADING OF EXISTING STRUCTURES, MEP EQUIPMENT MAY BE SUSPENDED OR PLACED ABOVE THE
DFE ON PEDESTALS OR PLATFORMS.

21. ELECTRICAL SYSTEM
• EQUIPMENT SHOULD NOT BE ATTACHED TO OR PENETRATE THROUGH BREAKAWAY WALLS
• WHEREVER POSSIBLE, EQUIPMENT SHOULD BE LOCATED ON THE SIDES OF PILES AND COLUMNS FROM THE
ANTICIPATED DIRECTION OF FLOOD FLOW AND WAVE APPROACH.
• EMERGENCY GENERATORS ARE REQUIRED TO PROTECT VITAL EQUIPMENT AND PROCESSES DURING AND AFTER A
FLOOD EVENT. LOCATE EMERGENCY GENERATORS AS HIGH AS POSSIBLE.
• AT A MINIMUM, THE GENERATOR SHOULD BE PLACED ABOVE THE MAIN ELECTRICAL SERVICE EQUIPMENT.

22. PLUMBING SYSTEM
• PLUMBING SYSTEMS MUST BE PROTECTED BY ELEVATION OF SYSTEM COMPONENTS. PLUMBING PIPES THAT ARE
ENCLOSED MAY RUN THROUGH AREAS BELOW THE DFE, A PRACTICAL NECESSITY FOR CONNECTIONS TO IN-GROUND
WATER AND SEWER SERVICES.
• PLUMBING CONTROLS, TANKS, SHUT-OFFS AND VENTS MUST BE LOCATED ABOVE THE DFE, ACCESSIBLE FOR
EMERGENCY ACCESS DURING FLOOD, WITH BACKFLOW PREVENTION INSTALLED ON THE WASTE WATER CONNECTION
TO PREVENT CONTAMINATION OD BUILDING WATER SUPPLY OR INTERIOR.

23. BACKFLOW AND AUTOMATIC SHUT-OFF VALVES
• BACKFLOW VALVES ARE DESIGNED TO TEMPORARILY BLOCK PIPES AND PREVENT FLOW INTO THE BUILDING. THEY
SHOULD BE INSTALLED ON ANY PIPES THAT LEAVE THE BUILDING OR CONNECTED TO EQUIPMENT OR SANITARY
SYSTEM LOCATED BELOW THE FLOOD PROTECTION LEVEL.
• IN ADDITION TO SANITARY SEWER AND SEPTIC CONNECTIONS , THIS REQUIREMENT MAY INCLUDE WATER LINES,
WASHING MACHINE DRAIN LINES, LAUNDRY SINK AND SUMP PUMPS.
• FUEL SUPPLY LINES MUST BE EQUIPPED WITH FLOAT- OPERATED AUTOMATIC SHUT-OFF VALVES.