The Geological Factors Contributing to Subsidence in London

London’s susceptibility to subsidence is influenced by its unique geology and climate. Much of London is situated on layers of clay, silt and sand deposited by the Thames River over millennia. While seemingly stable, these loose alluvial deposits can consolidate and subside unevenly when overloaded or saturated. Excessive groundwater extraction and development also increase subsidence risks. London’s temperate maritime climate, with substantial winter rainfall and mild summers, contributes to fluctuating soil moisture and movement.

If you are a homeowner in the West or City of London around postcodes W2, W3, W4, W5, W6, W7, W8, W9, W10, W11, W12, W13, W14, your property could be at risk of subsidence. London Clay Studies have shown that many properties in these areas have suffered from the effects of subsidence resulting in issues such as cracked walls, sinking floors or extension shifting away from the original structure.

Signs of Subsidence

If you’ve noticed any signs of subsidence damage in your property, contact us today. We provide free evaluations and quotes, call us on 0333 1300592 or fill out our short contact form.

London Areas Affected by Subsidence

Composition of London Clay and the signs of property movement

The bedrock under London consists largely of London Clay – a dense bluish-grey clay formed during the Eocene period approximately 56-49 million years ago from fine sediment accumulation in a shallow sea. Composed predominantly of clay minerals like illite and montmorillonite, London Clay has low permeability, high compressibility, and is prone to volume change from water content variations.[1] This makes it susceptible to shrink-swell subsidence when seasonal moisture levels fluctuate.

Cracks in walls and skirting board gaps could be subsidence

Effects of London Thames Alluvium – Overlying the London Clay are alluvial sediments deposited more recently during the Quaternary period by fluvial activity, especially from the Thames River. This alluvium consists of layers of silt, clay, sand, and gravel up to 22m thick, interlaid with pockets of peat.[2] Areas of thicker, less consolidated alluvial deposits tend to be more vulnerable to settlement from loading or drying. Differential settlement arises when adjacent areas have non-uniform alluvial layers.

Cracks in walls London clay city subsidence sign sinking floors skirting boards resin injections solution repair fix

We are here to help homeowners, landlords, property owners, housing associations and in fact any property owner across the UK fix cracks, sinking floors and sloping windows or doors that appear in buildings due to subsidence. The method we use is normally done in a day, there is little or no mess, and we also give you a warranty for the work we complete.

We are committed to giving you the best experience we can – giving you an efficient and friendly service with the best advice, the most experienced workforce and the lowest fixed prices to make the work affordable for you.

How Resin Injection Works to Fix Subsidence

You’ve heard of structural underpinning, the structural repair approach to sinking floors and cracks around windows, here’s a faster and more economical way of rectifying the signs of subsidence – with resin that acts like concrete and is injected deep into the affected foundation regions outside of your home.

First, when you contact us we will go through the job with you, either in person or on a video call, to look at your property and confirm that you have subsidence. At this point, we can give you a rough price for the job, and also talk to you about payment and discount options.

We will then give you advice on the next steps you need to take, which will normally be for you to instruct an independent site investigation and a drain survey. These surveys must be independent as they are YOUR surveys, however, we will give you advice on people that you could use for this and let you know roughly what cost to expect for these to be done.

Once you have the site investigation and drain survey completed and we have received a copy, we will then go about designing your job and giving you a fixed price for the job. Once you are happy with the arrangements, then we will arrange a date that is convenient for you.

Before the day of your work is carried out, we will keep in regular contact with you to make sure that we are both ready for the work on the day. If there is any preparation work required, we will go through this with you and make sure that it’s completed before the big day!

What to Expect From Subsidence Repair

We will tell you the names of the engineers that are coming before the day. All of our engineers are DBS checked and will carry out the work to our high standards. If you are available, the first thing our engineers will do is talk you through the job and make sure that you can maintain access to your property while we do the work.

They will then prepare to do the work, by marking out any underground services so we know where they are, and if they are near any injection point then they will hand-dig down to find and expose the services so we don’t damage them. The engineers will then mark out all the injection points and put laser survey equipment out to monitor the levels of your property as we do the work.

Once this preparation work is completed, the Subsidenceltd engineers will then drill holes at the injection points down to the required depths, insert injection tubes and then place a mushroom cap on the top so they are visible and safe!

Now the fun begins, as the engineers start to inject the resin material into the injection tubes – at this point the engineers will be injecting the material whilst keeping an eye on the laser survey equipment to monitor the lift of the property. As the material is injected the tubes will be removed until the full depth of the injection point has been treated. This process will be repeated until all of the injection points have been completed and the foundation of your property has been lifted and stabilised.

Throughout this whole process, our engineers will do whatever they can to ensure that there is no mess in and around your property.

Once completed, the property has been lifted and re-levelled where possible, this then leaves you to do cosmetic work, such as patching up any visual cracks that remain, and painting or repapering your internal walls. Don’t worry, we will be on hand again to give you advice on what you need to do to achieve the best outcome!

Call us today on 0333 1300592 or fill out our enquiry form here.

UK Subsidence Postcode Hotspots

Some postcode areas of the UK are more susceptible to Subsidence, we have a comprehensive list of affected postcodes in the UK including, East London, South London, City, Midlands and East Anglia

Sources: [1] Hight, D. et al., 2003. Characterisation of the London Clay. In Characterisation and Engineering Properties of Natural Soils
[2] Ellison, R.A. et al., 2004. Geology of London. Special memoir for 1:50 000 geological sheets 256 (north London), 257 (Romford), 270 (south London) and 271 (Dartford) (England and Wales). British Geological Survey.

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