Not Every Home with a Title Deed and Occupancy Permit Is Safe: Pay Attention to Flood Risk When Buying a House!

Stating that looking only at the title deed, building permit and occupancy certificate is not sufficient when purchasing a residence, Üsküdar Üniversitesi Emergency and Disaster Management Program Lecturer Tuğçe Yılmaz Karan said, “A building being legal does not mean it is risk-free against disasters.” Pointing out that opening streambeds to construction, closing off natural waterways and increasing concretization are heightening flood risk, Karan emphasized that before buying a house, flood hazard maps, past flooding incidents and infrastructure conditions must definitely be researched.

Üsküdar Üniversitesi Emergency and Disaster Management Program Lecturer Tuğçe Yılmaz Karan stated that the recent flood and inundation events have brought deficiencies in urban planning back onto the agenda, and expressed that flood risk should also be taken into account during the home-buying process.

Concretization Is Increasing Flood Risk

Noting that the natural movement of water is not sufficiently taken into account in urban planning, Lecturer Tuğçe Yılmaz Karan said that opening streambeds to construction, narrowing or closing off natural waterways, and the concretization of green spaces play a significant role in turning heavy rainfall into a disaster.

Karan made the following assessment on the subject:

“The flood and inundation events experienced recently show that the natural movement of water is not sufficiently taken into account in urban planning. The opening of streambeds to construction, the narrowing or closing of natural waterways, and the concretization of green spaces play a significant role in turning heavy rainfall into a disaster. Under normal conditions, part of rainwater seeps into the soil, but with the increase of impermeable surfaces such as concrete and asphalt, water rapidly turns into surface runoff. Increased surface runoff can cause the capacity of rainwater infrastructure to be exceeded, leading to flooding. Therefore, the issue is not only the intensity of the rainfall, but whether cities are planned in a way that can allow rainwater to seep into the ground, retain it when necessary, and safely drain it away.”

Examine Flood Maps Before Buying a House

Emphasizing that looking only at the title deed and permit documents is not sufficient when purchasing a residence, Karan stated that information on flood risk should be obtained from the relevant institutions.

Karan said, “First of all, a zoning status document, plan notes and, if available, institutional opinions regarding flooding should be requested from the relevant municipality. The studies of the State Hydraulic Works (DSİ), metropolitan municipalities and the relevant water and sewerage administrations regarding flood hazard can be examined. Specifically in İstanbul, İSKİ's assessments regarding stream protection zones and flood boundaries are important. Old maps, satellite images, past flooding records and the observations of neighborhood residents are also guiding. Because some areas may be known in the local memory as flood-prone areas. However, the fact that an area does not appear risky on current maps does not mean it is completely safe.”

Title Deed, Permit and Occupancy Certificate Do Not Guarantee Flood Safety

Pointing out that a building having legal documents does not mean it is safe in terms of flooding, Karan made the following statement regarding the scope of these documents:

“The title deed shows ownership status, the building permit shows the permission granted for construction, and the building usage permit, that is, the occupancy certificate, shows the administrative suitability for the use of the building. However, none of these documents alone guarantees that the building is safe in terms of flooding. Because flood risk is related not only to the building itself, but also to the characteristics of the land it is located on, the drainage infrastructure and environmental conditions. Even in areas that have been used as residential zones for many years, flood risk can grow due to increasing concretization, inadequate infrastructure and changing precipitation conditions. A building being legal does not mean it is risk-free against disasters.”

Being Far from a Stream Does Not Mean Being Safe

Stating that a building being located a certain distance from a streambed does not provide safety on its own, Karan said that flood risk should be determined by evaluating different land and environmental conditions together.

Karan shared the following information:

“It is not scientifically correct to state a fixed safe distance valid for every stream. While distance from the stream is important, it is not sufficient on its own. The slope of the land, its elevation, the permeability of the ground, the carrying capacity of the stream and past flood records should be evaluated together. For example, a building that is far from the stream but located at a low elevation may carry more risk than a building that is closer to the stream but located at a higher elevation. What is actually important here is which areas and up to what level the water could reach in a possible flood. Therefore, safe construction boundaries should be determined in line with flood hazard maps and area-specific technical studies.”

Danger Continues in Streambeds That Have Been Covered Over

Stating that old streambeds in cities that have been covered over or had their routes changed continue to carry risk, Karan emphasized that natural water flow cannot be completely eliminated through physical intervention alone.

Karan said, “Covering over a stream or changing its route does not mean that the natural movement of water in that area has completely disappeared. During heavy rainfall, water may follow the natural slope of the land and head toward its old flow routes. Especially if the capacity of covered stream sections is insufficient or becomes blocked, serious flooding can occur on streets, in parking lots and in residences. For this reason, construction over old streambeds should be carefully evaluated. You can cover over a stream, but you cannot eliminate water's need for natural flow.”

Basements and Enclosed Parking Lots Carry Vital Risk

Stating that flood risk should be questioned along with earthquake resistance when choosing a residence, Karan pointed out that basement, entrance and garden floors may carry higher risk in terms of flooding.

Noting that vital dangers such as damage to electrical installations, backflow of sewage and people becoming trapped can arise in these areas, Karan said that enclosed parking lots should also be carefully examined.

Karan said, “In enclosed parking lots, the slope of the entrance ramp, the elevation difference between the road and the building, rainwater drains and evacuation pumps should be examined. The building's waterproofing and drainage infrastructure are also important. In sudden flooding, it is vitally important not to go down to basement floors and enclosed parking lots.”

Be Sure to Make These Five Checks Before Buying a House

Stating that citizens who will buy a residence should conduct comprehensive research regarding flood risk before giving a deposit, Lecturer Tuğçe Yılmaz Karan listed the five fundamental points to pay attention to as follows:

1. Location of the land: Is the building in an old streambed, a flood zone, or a low-elevation area prone to water accumulation?

2. Official records: Is there risk shown in the municipality's zoning plans, DSİ data and flood hazard maps?

3. Past flooding: Has the building or its surroundings experienced flooding before? Has information been obtained from neighbors and the site management?

4. Infrastructure adequacy: Are rainwater drainage, basement waterproofing, the parking lot evacuation system and sewage backflow precautions sufficient?

5. Technical assessment: If there is a suspicion of risk, has an opinion been obtained from an expert competent in flooding?

Water Traces, Dampness and Mold in the Basement Can Be Warning Signs

Stating that traces of past flooding in residences should also be investigated, Karan said that dampness, mold and water traces in basement floors should be taken into account.

Karan said, “The presence of high flood hazard in official records, recurring flooding and unresolved serious infrastructure deficiencies are important warning signs. The presence of water traces, dampness and mold in basement floors, or the building entrance being below street level, should also be investigated separately. If it cannot be demonstrated through technical assessments that these risks have been reduced to an acceptable level, the decision to purchase the residence should be reconsidered.”

Safe Land Is as Important as a Solid Building

Emphasizing that a safe residence does not consist only of a solid building, and that the characteristics of the land the building is located on must also be taken into account, Karan completed her remarks as follows:

“A safe residence does not consist only of a solid building; the land the building is located on must also be safe. For this reason, when purchasing a residence, we must question flood risk as much as earthquake resistance. Because sometimes the real risk arises not so much from the building itself, but from the characteristics of the area it is located in.”