Purchasing a new house located in a low flood risk but surrounded by Flood Zone 2/3.

propertyrental

user1977 said:

Which don't you understand? "Ordnance Datum" is just sea-level.

to be more precise it is mean sea level, since sea level varies according to the tides...... but I'm splitting hairs here!

Maka344

Thank you, I'm still not sure what it means in terms of context and future flood risk. 

user1977

Maka344 said:

Thank you, I'm still not sure what it means in terms of context and future flood risk. 

On its own, not much, it's just telling you what the altitude of the land in question is (and obviously the land which is lower than 18m above sea level is likely to be under water first...)

RHemmings

It helps if your lower flood risk part looks a bit like this:



rather than it being a gentle slope and small difference in elevation compared to the bits with higher flood risk. 

Maka344

The concern is with climate change getting worse, could this close the gap highlighted on the map. We have run a couple of insurance quotes, which are coming out at £1000, more than double.

On balance, we are thinking that it is probably best to walk away. I am not comfortable with the level of risk involved, especially the potential de-valuation and insurance issues should that gap close. 

According to the topographic map, the house is 20m above sea level. 

Albermarle

Maka344 said:

The concern is with climate change getting worse, could this close the gap highlighted on the map. We have run a couple of insurance quotes, which are coming out at £1000, more than double.

On balance, we are thinking that it is probably best to walk away. I am not comfortable with the level of risk involved, especially the potential de-valuation and insurance issues should that gap close. 

According to the topographic map, the house is 20m above sea level. 

The problem is that if you let such minor worries put you off buying a house, then it is going to be a long search.
The next one might have some cracks, or the survey recommends a new roof, or needs rewiring, or has some issues with shared driveways etc etc .There is always something  and there are numerous threads on here like this one.
Issues with the survey — MoneySavingExpert Forum

Two insurance quotes is not enough, Try running some more.