Risk of subsidence

[Mazzatron]

We have just heard via the searches that the property we are buying is at moderate to high risk of being affected by subsidence.

No idea what to do now! Does anyone have an tips on how we can investigate further?

The survey did not identify any recent evidence of subsidence / movement.

Really keen to still purchase the property but don't want to make a silly mistake

Did it say what the risk was due to? Mine shafts? London Clay?

@HomeHomeInTheRange it says it's natural ground subsidence based upon the natural qualities of the geology at the site rather than any historical claims or events. It's a built up coastal area. It's about 15 mins walk from the sea.

Subsidence risk is based on ground (clay usually) that shrinks and expands and lack of suitable foundations. Trees nearby can take moisture out of soil too. Deep foundations mitigate risk to a great extent and properties that don’t have them are more at risk. To say risk I’d purely geology based is ridiculous. You don’t see tower blocks having subsidence! They have suitable well designed foundations.

@TizerorFizz ok thanks. So should we go back to the solicitor and ask for more details? Or ask the surveyor to look into the foundations? Sorry - we are very new to all this.

It's a 2 storey house built in 1929. The survey noted some cracks by a window in dining room and bedroom above and said they didn't appear recent and no recent evidence of movement

Also there are some large trees in the garden @TizerorFizz

Sounds like they are just covering their backs.
A few old cracks in a house built in 1929 is probably ignorable but I would try to get more details.
Are there large trees nearby ?

Are the trees protected. We had subsidence but the previous owner had planted 3 leylandii about 10 ft to 15 ft from the house.
Our insurance covered the repair, trees were removed.

I probably would not worry too much if the cracks are deemed not be to recent. However 1920s houses probably didn’t have deep foundations but they are probably adequate. I would ask the surveyor about the size of the cracks and if they represent historic settlement. Are bricks split? Is render split? Are they hairline or big enough to put a coin in? Are they jagged?

The trees might not matter if they are not too close to the house but roots can cause debate to drains. The type of tree can matter too. Some drink more water than others. However if there’s not much sign of any damage, it’s all probably fine.

Thanks @TizerorFizz . The surveyor is now away until April 5th annoyingly.
They did recommend we get a specialist drainage company to inspect the drains with a camera so will be doing that ASAP.

I also think the surveyor would have been more specific about the cracks if they were concerned about them. Hope the drains are ok.

Well the drains had 4 blockages and damage from tree roots which has now been sorted. We are waiting to hear if two large trees in the garden have TPOs on. If they don't, we will go ahead with the purchase!

Be very careful about felling trees. Get them cut back. Trees drink a huge amount of water every year. If they are removed, where is the water going to go that they would have consumed? It frequently stays in the soil and can lead to heave which is where the soil swells and pushes walls outwards. So take a more considered route than felling immediately. Even if a tree has a tpo, you can apply to have it cut back.

@TizerorFizz right ok. Very useful info - i was wondering if there is no tpo why the current owner left the tree there for so long. It does look maintained. Thanks very much again!

It's stayed up nearly 100 years so I think that's a good sign...

I'm buying one with a similar level of risk of natural subsidence. So watching this thread with interest.

@Hostaswordwoman
I’m afraid that’s very poor advice and frankly, rubbish. A house with subsidence is not insurable. The current owner has to claim on their insurance. My DD has dealt with modern houses with cracks so big you can see daylight through them. Heave pushes walls outwards. Just because a house has been there for years it doesn’t mean anything at all if it’s foundations are compromised. It still might even need to be demolished.

@TizerorFizz do you know of any specialist professional that could investigate this and do a report for us? We had a tree surgeon look and he said that the two trees closest are a risk to the property and need felling - however he couldn’t comment on how this might affect the foundations.

You need a structural engineer. One with experience of foundations and soil composition.

They are just covering their backs. Most U.K. homes are technically at risk of subsidence especially over 50 years old as foundations wear not very deep

It helps if you know what type of tree they are, how tall they are, how close they are to the property and what the underlying soils comprise (clay rich soils / clay strata will have the greatest capacity for shrink / swell behaviour).

You need an engineering consultancy with geotechnical engineering expertise.

Incorrect. We had subsidence and are insured. We have changed our insurers with the subsidence fully declared - sent the new insurer a copy of all the reports.

It’s insurable after the work has been done and it’s stable. You now say it “had” Subsidence. Not a house currently with cracks. For a buyer taking on a house with known subsidence: it’s not insurable by them. The existing owner must claim for the work. DH is FIStructE and this is standard practice.

The risk of subsidence bit is scary. Our house has “moderate” risk of subsidence and it freaked me out at first. However it is worth bearing in mind that the majority of houses in London are rated “high” due to clay soil - most peoples houses don’t fall down. Often it is due to area rather than house so I would expect to find the exact same result on another house you look at - unless you move area completely. Our whole area of town is “moderate”

@NewGardenProject

The op says moderate to high.

The main thing to remember is that if there are no visible cracks in the house, then it’s not suffering from subsidence. All surveyors would have picked this up.

You will find the high risk is down to soil. If the house is fully insurable, then you should also be able to insure it. If it’s in good condition, then it’s fine. Therefore you might decide to do nothing before you buy.

Houses rarely fall down with subsidence. They are repaired and hardly anyone knows!

Thanks @TizerorFizz you've been super helpful.
Thanks @TheAbbotOfUnreason also
Well we're going ahead with the purchase. It seems pretty much the whole town is the same risk of subsidence. Super excited. Interesting times ahead!