Subsidence concerns in London for first time buyers

[Aquietplace4me]

A family member and her husband are looking to buy their first property in London. They've worked very hard to save for a decent deposit and are now in the viewing/about to make offers stage. Does anyone know anything about Dulwich - specifically East Dulwich - and subsidence issues? I don't live near London but they're asking my advice generally re houses and purchasing etc - much of which I can help them with in a general sense as I've bought and sold a fair bit, but I don't know London.

Googling seems to show it's a known hotspot for subsidence with the clay, but also it seems to be a popular area for young couples/families etc and houses do seem to sell often - though I'm not familiar with how 'hot' (or not) the market is there currently. To me, it seems a vast amount of money for a property that could potentially have future subsidence (there are some cracks visible on viewing apparently, but very hard to tell from the pics how bad - they don't look huge or anything but I don't know if it's just plaster or if they run deeper into brick).

Apparently, any existing cracks at the rear were caused by tree(s) that have now been removed. Naturally, they're trying to avoid forking out for costly surveys and then pulling out because subsidence is flagged. A quick building regs search tells me two of the houses two doors down (same side/terrace) have been underpinned. I don't think they'd want to get into remedial works even if there was a reduction to cover this.
Any advice/thoughts on this area? Are there any specific roads to avoid or is it pot luck? Thanks! :)

As the saying goes in London... there's the houses who know they had/have subsidence and those that don't know they have it.
My property had. My neighbours' (it's a terrace) have not. There's just no way of knowing short of a survey

They would be crazy to buy without a survey.

London is built on clay so the whole city is potentially at risk of subsidence. They need a surveyor to advise specifically on the house they are looking at.

They're definitely getting a survey! Maybe I worded it badly - what I meant was, they don't want to pay for a costly survey just to be told there's subsidence because it's XYZ Street - or because near neighbours were underpinned etc - and then pull out. I was wondering if there were more specific known hotspots within this area... but as you say, most of the city is clay, though it seems some areas are more prone than others.

Haha a wise saying, no doubt. I think they need to get their heads around the cost of the survey and potentially pulling out (maybe on a few houses) being part of the cost of buying.

Cracks on a viewing don’t automatically mean subsidence, but I can understand not wanting to spend money on several surveys if you’re likely to pull out.

I’d ask the agent in writing about any previous movement, underpinning, insurance claims and guarantees, and whether the neighbours’ properties have had work done. Look at the cracks closely: a hairline crack in plaster is very different from a widening diagonal or stair-step crack through masonry, especially if there are matching cracks inside and out, sticking doors or sloping floors. Photos and measurements over time are useful, but don’t try to diagnose it from a postcode or clay map alone.

If the house is otherwise a serious contender, a Level 3 survey with the surveyor specifically asked to comment on the cracking is a sensible first step. If they remain concerned, ask for a structural engineer/chartered building surveyor with subsidence experience to inspect it and say whether monitoring is appropriate. Also check that buildings insurance is available on normal terms before exchange. A survey is part of the cost of buying, but it should give you a property-specific answer rather than just “London is on clay”.

I lived in e dulwich for decades without any problems. Make sure the sellers have declared there hasn't been subsidence , or that it's been sorted before going ahead. But you must get a survey.

They should get the full structural survey. It’s about £1K, peanuts compared to the price of a property in this area. It’ll be full of caveats but will give them a clearer idea of anything that might potentially be concerning.

I have just moved from the East Dulwich/ Forest Hill borders after 50 years, and there is a LOT of subsidence in several roads in the immediate area - our road was particularly notorious, but we lived in four properties in one road and the one running parallel during that time. The first property we bought in the road was a flat in a conversion in 1980, and the house was underpinned the year after we moved in. It didn’t make it more difficult when we came to sell it, and no further repairs have ever been needed. We bought our last house, in the same road, in 1992, and had major structural repairs carried out in 1997. The movement was partly caused by tree roots, partly due to a long dry period, traffic vibrations, and partly by the concrete roof tiles, which were too heavy for the roof structure. We were there for nearly 30 years after that, but had no further serious subsidence once the work had been completed. It wasn’t an issue at all when we sold the house this year, and hasnt been an issue for any of our neighbours who have moved in recent years. The majority of the houses on our side of the road had been underpinned over the years, and many neighbours found that small cracks often opened up in the autumn after a dry summer, which were just filled. Before we moved, several neighbours mentioned that they were noticing new cracks, but I assume thst will be common in many areas after the hot, dry summer. I would never be put off buying a house which had been underpinned in an area like East Dulwich where many of the old houses were built in clay and with very shallow foundations.

One more thing that often gets missed: ask the vendor for the insurer’s claim-closure letter, and any monitoring results from after the work. That paperwork tells you whether the claim was closed as “resolved” or just “no further movement recorded for now,” and whether they kept an eye on it for a proper period afterwards. If those aren’t available, that’s useful information in itself before you commit.

Full disclosure, as my username gives away, we do independent builder reviews of survey reports, so happy to answer anything else on here.

We have bought in London - with cracks due to a nearby bomb in WW2. You can also have cracks from being on top of tube lines. There’s just a lot of old housing stock and a lot going on which can affect it. All you can do is get a survey. I think when we bought the house with cracks they had to source a map showing where the bombs had fallen.

We're in north London not Dulwich but as pp said pretty much all of London is built on clay. The last few months reeeeally haven't helped weather-wise - five properties on our road posted on the street Whatsapp group within days of each other in late Aug looking for structural engineer recommendations!

Your relatives should 100% fork out for the full survey but also be mindful that to some extent it's just the nature of these houses, particularly the bay windows, and that the way our climate is going it will be an increasing problem, but not necesaarily one to panic about.

One thing that might help with the survey-money worry: there are a few cheap checks you can do before paying for anything. Ask for a buildings insurance quote with the address declared - insurers price subsidence risk very bluntly, and if the premium comes back normal that tells you something. Ask the agent, in writing, when the trees at the back came down. That bit caught my eye, because on clay the ground can swell back up once a big tree is removed (heave), which is a different problem from the shrinkage people usually mean, and a surveyor will want to know the timeline either way. The underpinning two doors down is not necessarily a bad sign, honestly - it can mean the road has been looked at and fixed, rather than ignored. Worth asking whether those works came with a guarantee, and whether this house has any record of the same. If the cracks are the only worry, a one-off visit from a structural engineer before the full survey is often a few hundred pounds, which is a lot easier to swallow on a house they might walk away from than a Level 3 on every one. Good luck to them, it is a stressful stage!

Thanks everyone for your help/thoughts/comments. All very helpful and I'll pass them all on. Good idea to check past insurance docs/see the outcome. They've apparently been told what the current insurance premium is per year (not sure if it's contents as well) and I guess it seems about right as it's London (everything seems pricey to me there!). And it's with a run of the mill well-known insurer, which I guess bodes well. I think their main aim is to be as informed as possible before committing to larger survey fees (they'll 100% be getting a full survey) and potentially having to pull out for something they could have discovered before paying survey fees. All part of the buying process, though! Thanks again, all :)