Independent Subsidence specialists. 15+ years of resolving complex subsidence issues
Independent Subsidence Experts
In the insurance industry the phrases subsidence Surveyor or subsidence Engineer are used for a professional with suitable training and experience.
We have a wealth of experience with Insurance subsidence claims. We are independent and our opinions are always independent, robust and impartial.
We assist Building owners, Loss Adjusters, Brokers and Insurers to determine causation of damage. We arrange for and report on detailed opening up works, investigations, monitoring and repairs.
What to expect from AIM Surveying
A friendly, professional and personal service.
Initial free phone/video consultation
We will get to understand the issues and determine what service is required.
A thorough site inspection
We will attend site to carefully asses the damage and the potential causes. After the survey we will provide you with a detailed verbal overview of our opinions.
Alternatively we can review photo and videos.
This will include
- a description and photographs of the damage
- our firm opinion on what has caused the damage
- should the damage be a valid insurance claim
- advise if monitoring or investigations are necessary
- what needs to be done to prevent further structural movement
- is underpinning required
- what crack repairs are required
Further reports can be provided on the outcome of monitoring and investigations.
What is Subsidence and Heave?
Very simply, subsidence is a downward movement of the ground below the foundations and heave is upward movement.
Damage occurs when one part of the building moves and another part remains stationary. This differential movement creates cracking.
What causes Subsidence and how to stop it?
There are two common causes amongst others.
The first common cause is trees and vegetation. The fine roots below the foundations will extract moisture and cause any clay soils to shrink. This clay shrinkage results in downward movement of the foundations.
In many circumstances it is safe to remove the vegetation. The clay soil can rehydrate and the clay will swell up to its former size. This hydration will lift the building, close the cracks stabilise the building.
Significant volumes of water escaping from drains, water mains and plumbing pipes etc, can soften clay soils or wash away material particularly in soils with silt, sand and gravel. This weakening of the bearing capacity of the subsoils results in downward movement of foundations.
Repairing the leaks will typically allow the building to stabilise.
There are less common causes for subsidence movement. This could relate to mining subsidence or the collapse of an old well or culvert, peat soil losing its water content, differences in the inherent nature of the superficial geology across the site, the nature of the construction of the property or consolidation of made ground.
On these occasions it is likely professional assistance would be required.
Subsidence is typically a slow process and occurs over a period of months or years depending on the cause. Sometimes it is necessary to collect additional information and evidence.
We can make recommendations for monitoring and provide interpretation of the results. It may be necessary to undertake readings for 6 to 12 months.
Detailed level monitoring
Markers are fixed to the external perimeter of the building and the readings taken over a period of time are compared relative to a fixed datum reference point which is not suffering from subsidence movement. This is a more direct measure of ground movement.
Can be used as an alternative or complement. This involves gluing small metal studs across the cracks and using a set of callipers to measure the very small changes in the crack widths over time.
We can make recommendations for geotechnical investigations and laboratory testing of soil and root samples. At the property, this simply involves digging a small trial pit to determine depth and type of the foundations. From the bottom of the trial pit, a narrow borehole is extended downwards to investigate the soil below the foundations. It may be necessary for soil samples and root samples to be sent off to a laboratory for analysis.
Drainage investigations and repairs
We can make recommendations for a CCTV survey of the underground drainage or testing of the incoming water mains for example.
On receipt of the results, we can provide advice on what are the essential repairs and how can this be done economically with as little disruption as possible.
In some circumstances, it is not possible to stop progressive movement and underpinning cannot be avoided. In those circumstances we can recommend an underpinning technique appropriate for the soil conditions and the cause of the movement.
In most circumstances, only crack repairs are essential. We can specify a robust repair scheme which is appropriate for the type of construction and severity of the damage. Common crack repairs are repointing, brick stitching with the inclusion of heli-bar reinforcements.
Performing the role of Principal Designer under the CDM regulations.
Provide a detailed Schedule of Work to accurately define the scope of the repair.
Undertaking competitive tendering to get prices from suitably qualified contractors Advise on construction contracts and provide full Design and Contract Administration services to see a project through to completion.
Third party issues
In some circumstances, the subsidence movement may be caused by trees or drains which are owned by third parties.
Third party trees
Where trees are owned by third parties, we can provide assistance in collecting the proportionate evidence and presenting it in an appropriate way, whether the tree owner is a domestic neighbour, a Local Authority Council or a commercial business entity. We can assist with correspondence and with taking the right steps at the right time to provide a compelling argument to resolve the matters as soon as possible.
Third party drains
Shared drains, even within the boundary of a domestic property are likely to be in the ownership of the local Water Authority.
We can assist with collecting the right evidence and presenting it in an appropriate way to ensure third party drain owners take action.