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Original poster

Which risk is worse?

33 replies

Milikite · 21/08/2023 17:48

Property A is “high” risk for groundwater flooding. Property has never been flooded before but the searches flag it as an issue.

Property B is “very high” risk for subsidence. Again, no subsidence at the property to date but the searches flag it as an issue AND the climate change report says it is “very likely” to “extremely likely” to occur in the future (2030s and 2050s). The risk seems to be driven by trees in the property, at least four of which are protected by tree preservation orders. Two are oak trees, which are apparently among the worst for causing subsidence.

Any thoughts on which is the worse risk to put up with, groundwater flooding or subsidence? I always thought flooding was worse because subsidence doesn’t mean you have to move out, right? But maybe those who have suffered subsidence would disagree?

OP posts:
RidingMyBike · 21/08/2023 18:10

What's the rest of the area like? Is one or both of these going to affect most of the area you're looking in?

Callisto1 · 21/08/2023 18:15

Going on the limited info you give, I'd think flooding is worse than subsidence. I mean you could always underpin or reduce trees. With water you will just have to fix the damage afterwards.

Original poster
Milikite · 21/08/2023 18:19

@RidingMyBike in the case of the subsidence, the property and it’s semi-detached neighbour have an elevated risk of subsidence compared to all the other properties in the area. Subsidence is a general issue in the area but clearly the trees drive up the risk massively. I would be fine with this if we could manage the trees but there are TPOs in place.

I don’t know about the risk of groundwater flooding to other properties in the neighbourhood of property B but I would imagine the whole street would be the same.

OP posts:
Original poster
Milikite · 21/08/2023 18:21

@Callisto1 I thought the same as you but it’s not exactly like for like because the subsidence risk is especially high whereas the flooding is just high. Reducing trees that are protected might be a complete nightmare…?

OP posts:
Callisto1 · 21/08/2023 18:28

Very high risk vs high risk means nothing if you don't have actual numbers. Are you even sure that the subsidence and flood risk have the same scale?
I would ask about the trees. Someone in the council will know what maintenance you are allowed to do on them.

WaitingfortheTardis · 21/08/2023 18:31

I'd check why the flooding is as reported, our surveys indicated a drain on the road that made us a medium risk. In reality it was wrong on the map and is downhill from the house rather than uphill. Once I'd checked that I'd explore the type of subsidence risk and whether insurance is available, it can often be fixed but is expensive to do so.

Ivyusername · 21/08/2023 18:32

This reply has been deleted

This has been deleted by MNHQ for breaking our Talk Guidelines.

SabrinaThwaite · 21/08/2023 18:33

Groundwater flooding can be nasty because it rises slowly and falls slowly.

Oak, elm, hawthorn, poplar, willow and eucalyptus are all high water demand trees.

How tall are the trees and how close are they to the property? Roughly whereabouts in the country are you looking?

Original poster
Milikite · 21/08/2023 18:39

Callisto1 · 21/08/2023 18:28

Very high risk vs high risk means nothing if you don't have actual numbers. Are you even sure that the subsidence and flood risk have the same scale?
I would ask about the trees. Someone in the council will know what maintenance you are allowed to do on them.

I’m just going on what I have from the searches so I don’t have numbers and I guess that it’s not possible to get numbers.

The subsidence seems to be almost certain to occur in the future because the risk is exacerbated by climate change whereas the groundwater flooding is not i.e. the groundwater flooding risk will not get worse.

I’m hoping to hear views from people on this forum who have experienced subsidence.

OP posts:
Original poster
Milikite · 21/08/2023 18:40

WaitingfortheTardis · 21/08/2023 18:31

I'd check why the flooding is as reported, our surveys indicated a drain on the road that made us a medium risk. In reality it was wrong on the map and is downhill from the house rather than uphill. Once I'd checked that I'd explore the type of subsidence risk and whether insurance is available, it can often be fixed but is expensive to do so.

How would you check why the flooding is as reported?

OP posts:
SabrinaThwaite · 21/08/2023 18:45

WaitingfortheTardis · 21/08/2023 18:31

I'd check why the flooding is as reported, our surveys indicated a drain on the road that made us a medium risk. In reality it was wrong on the map and is downhill from the house rather than uphill. Once I'd checked that I'd explore the type of subsidence risk and whether insurance is available, it can often be fixed but is expensive to do so.

Was that for surface water flooding?

Original poster
Milikite · 21/08/2023 18:46

SabrinaThwaite · 21/08/2023 18:33

Groundwater flooding can be nasty because it rises slowly and falls slowly.

Oak, elm, hawthorn, poplar, willow and eucalyptus are all high water demand trees.

How tall are the trees and how close are they to the property? Roughly whereabouts in the country are you looking?

There is at least one oak tree. I don’t know how close to the property but have asked. I think the trees are close to the building - certainly the oak is less than 30 metres. This is London so subsidence risk is everywhere because of the clay but this property has a higher risk than normal because of the trees. The fact that they are protected seems like a minefield so I want to run a mile. And yet flooding I’ve always thought of as worse. And @Ivyusername it’s one of these or nothing. They tick all other boxes. Plus my DH says you can’t get away from all risks.

OP posts:
Original poster
Milikite · 21/08/2023 18:48

SabrinaThwaite · 21/08/2023 18:33

Groundwater flooding can be nasty because it rises slowly and falls slowly.

Oak, elm, hawthorn, poplar, willow and eucalyptus are all high water demand trees.

How tall are the trees and how close are they to the property? Roughly whereabouts in the country are you looking?

I don’t know how tall the trees are or how old they are. Have asked for more info.

OP posts:
JusthereforXmas · 21/08/2023 19:35

Milikite · 21/08/2023 17:48

Property A is “high” risk for groundwater flooding. Property has never been flooded before but the searches flag it as an issue.

Property B is “very high” risk for subsidence. Again, no subsidence at the property to date but the searches flag it as an issue AND the climate change report says it is “very likely” to “extremely likely” to occur in the future (2030s and 2050s). The risk seems to be driven by trees in the property, at least four of which are protected by tree preservation orders. Two are oak trees, which are apparently among the worst for causing subsidence.

Any thoughts on which is the worse risk to put up with, groundwater flooding or subsidence? I always thought flooding was worse because subsidence doesn’t mean you have to move out, right? But maybe those who have suffered subsidence would disagree?

I live in a mining town (well every tow/village in the county is pretty much a mining town), subsidence is a risk everywhere. A sinkhole opened it just at the end of our street recently and anywhere you go here is a risk so overall its 'not a risk'. Despite this I don't know ANYONE thats had any issues (other than cosmetic cracks or wonky floorboards etc...) in my whole life.

I wouldn't touch a floor risk with a 6 foot barge pole. I do know 2 people whose houses flooded and it was a expensive nightmare for them... plus no insurance will touch you.

SupermarketMum · 21/08/2023 20:48

OP the subsidence risk scale essentially means: this property is X times more likely than the average UK property to make a claim due to subsidence. The subsidence risk being very high compared with a high risk of flooding does not mean that subsidence is more likely than flooding.

I personally would prefer something fixable like subsidence than flooding.

Callisto1 · 21/08/2023 20:48

Groundwater flooding could get worse also with climate change as we will experience more extreme weather. And as people pave over gardens. If you're affected you'd have to rely on your council/water company to improve the drainage. Good luck with that!

I live in Edinburgh and when it rains badly there are parts of town that flood. The road outside my flat becomes a stream! At the bottom of the hill it's a pond... Some people had flats flooded twice within 3 years. The drains simply can't cope. It's really scary how quickly it happens!

Original poster
Milikite · 21/08/2023 20:58

Callisto1 · 21/08/2023 20:48

Groundwater flooding could get worse also with climate change as we will experience more extreme weather. And as people pave over gardens. If you're affected you'd have to rely on your council/water company to improve the drainage. Good luck with that!

I live in Edinburgh and when it rains badly there are parts of town that flood. The road outside my flat becomes a stream! At the bottom of the hill it's a pond... Some people had flats flooded twice within 3 years. The drains simply can't cope. It's really scary how quickly it happens!

I would agree with you except that the searches include a climate change report and the flood risk (for groundwater flooding) is not affected by climate change. Perhaps surface water flooding is different. This report shows no increased flood risk from climate change.

OP posts:
BlueMongoose · 21/08/2023 21:03

Check the flood risk. We were involved in a community biulding which insurers suddenly decided was in a flood zone. Whe had to go and stand behind the property with a big measuring stick and take photos to send to them- the land it was on must have been well over 10 feet higher than the tiny stream behind they were worried about, and far higher again than the river flood plain beyond. The west coast main line and most of the adjoining town and areas for several square miles would have had to have been under deep water before it affected the building. It was just that their map contours were not accurate enough.

Original poster
Milikite · 21/08/2023 21:05

SupermarketMum · 21/08/2023 20:48

OP the subsidence risk scale essentially means: this property is X times more likely than the average UK property to make a claim due to subsidence. The subsidence risk being very high compared with a high risk of flooding does not mean that subsidence is more likely than flooding.

I personally would prefer something fixable like subsidence than flooding.

I guess that's what I'm trying to get a sense of - whether subsidence is generally considered to be more fixable than flooding. I was hoping to get a response from someone who has actually gone through subsidence. We would be planning to be in the property for 15-20 years. Reading the report it seems an absolute dead cert that there will be subsidence in that time. In the 2030s it is "extremely likely" according to the report! And that is in all climate scenarios i.e. wet scenario, dry scenario. I'm worried that it will be difficult to resell the property down the line.

OP posts:
Original poster
Milikite · 21/08/2023 21:06

BlueMongoose · 21/08/2023 21:03

Check the flood risk. We were involved in a community biulding which insurers suddenly decided was in a flood zone. Whe had to go and stand behind the property with a big measuring stick and take photos to send to them- the land it was on must have been well over 10 feet higher than the tiny stream behind they were worried about, and far higher again than the river flood plain beyond. The west coast main line and most of the adjoining town and areas for several square miles would have had to have been under deep water before it affected the building. It was just that their map contours were not accurate enough.

This is groundwater flooding, not flooding from rivers or streams. I have no way of checking the water table level?

OP posts:
Original poster
Milikite · 21/08/2023 23:15

Does anyone have any knowledge of how insurers view these risks? Would it be more difficult to get insurance on a property that has flooded or a property that had experienced subsidence, all other things being equal?

OP posts:
Diymesss · 22/08/2023 06:58

With the trees, you would need to keep an eye on them. One of my neighbours’ protected oak trees recently cracked in half and a huge branch fell, damaging several cars on the way down. Apparently the branch had become rotten. If a building had been in the way no doubt it would have smashed through the roof.

JusthereforXmas · 22/08/2023 07:02

Milikite · 21/08/2023 21:05

I guess that's what I'm trying to get a sense of - whether subsidence is generally considered to be more fixable than flooding. I was hoping to get a response from someone who has actually gone through subsidence. We would be planning to be in the property for 15-20 years. Reading the report it seems an absolute dead cert that there will be subsidence in that time. In the 2030s it is "extremely likely" according to the report! And that is in all climate scenarios i.e. wet scenario, dry scenario. I'm worried that it will be difficult to resell the property down the line.

Show quote history

We live on a steep hill and had work done on our house a while about 7 years ago. While drilling through the foundations they mentioned there is 'nothing' under our house (the original ground soil has washed away and our house is basically 'floating' being braced by the rest of the terrace who may be suffering the same for all we know). We have lived here a decade and a half and known this for 7 years but it hasn't effected anything at all.

Its a rented house so nothing 'we' can do about it but it has caused no issues.

JusthereforXmas · 22/08/2023 07:10

Milikite · 21/08/2023 23:15

Does anyone have any knowledge of how insurers view these risks? Would it be more difficult to get insurance on a property that has flooded or a property that had experienced subsidence, all other things being equal?

I don't know anyone thats had issues with insurance for subsidence but insurance usually won't touch a flood risk.

If the house shows no signs then its treat like a normal house. If the house needs work doing when you buy it they wont cover you for that but after the house has already been underpinned etc... they will see it as a positive as the risk has been fixed. Underpinning doesn't cost 'that' much in the grand scheme of it (about £10k) and any house you buy that currently needs it will be dirt cheap likely.

There was a row of houses built on the river bank when I was a kid (right on the flood plain, god knows who approved it) and they flooded every year. They ended up abandoned because people couldn't sell them on as no buyers wanted them apparently due to the impossibility of getting insurance on them. Im sure the flooding was also a reason but the lack of insurance probably hammered home that message.

Greenwitchhorse · 22/08/2023 07:25

I would not touch either of them. Change areas if needed.

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