Underpinning methods could be needed at Houses of Parliament
A Sunday Times report has hinted that a range of underpinning methods may be needed in order to save one of Britain’s most iconic buildings in the years to come.
Last week, we reported plans to refurbish Battersea Power Station, and noted the risks posed to the structure if a Tube line and station were to be added to the site.
Now it seems another landmark of the River Thames is suffering from vibration due to Underground trains – this time, it’s the Houses of Parliament that are under threat.
Since the Sunday Times broke the story of concerns raised by the House of Commons Commission, several other news providers have picked up on it, quoting repair bills of anywhere up to £3 billion in order to protect the seat of British government for generations to come.
And some of the largest-scale underpinning methods ever employed could be needed to prevent London from getting a ‘leaning tower’ to rival that of Pisa, as Big Ben has apparently moved several inches away from the vertical over the years.
But with proposals to move MPs to a different location for up to five years from 2015, many are already opposing the work – and it will be interesting to see what measures are taken to restore structural stability to Westminster in the years to come.
Battersea Power Station refurb could challenge underpinning techniques
Underpinning techniques could be put to the test in a whole new way as work to redevelop Battersea Power Station gets underway.
An £8 billion development plan was announced last month, which is expected to create 20,000 construction jobs as the iconic building is converted into homes, retail space, offices and a hotel.
Modern underpinning techniques may be needed to make sure the foundations of the building – which, at around 80 years old, is frequently described as being in poor condition – are up to the task of supporting residents, workers and shoppers.
But an extra challenge is likely to come in the form of plans to add a transport hub to the site, linking it with the London Underground’s Northern Line.
Even if this is done using above-ground tracks, the vibration of passing trains will mean strong foundations are essential for the Grade II* listed former power station.
The plans are just one part of London’s Olympic legacy, which UK Trade & Investment says has seen £14 billion of deals announced in the weeks since the Games began.
Mini piling rigs can help meet EU renovation targets
With a five-point plan outlined by the European Commission to help unleash the potential of low-energy buildings throughout the continent, mini piling rigs could play a key role in allowing existing structures to be brought up to date.
Renovation is one of the five main points in the plan, both to bring those buildings up to date, and also to stimulate investment conditions in EU member states’ construction sectors.
And it is in existing buildings, which may be on sites with other valuable infrastructure or neighbouring premises in place, where mini piling rigs can be particularly useful.
By using compact, low-vibration piling equipments, construction firms can make sure they do no damage to surrounding structures, or to any nearby underground infrastructure.
While it is impossible to carry out foundation work without disturbing the ground to some extent, it is likely that underpinning techniques which are as minimally invasive as possible will play a key role in the coming years, as this renovation-led plan for raising levels of construction investment goes into effect across the EU.
Underpinning can help keep non-moving households in place
With few British households planning on moving house in the next year, those considering home improvements might want to invest in underpinning if they see any evidence of subsidence in their property.
Subsidence can be spotted in several ways, from windows that have become hard to close due to shifting frames, to crumbling and cracked masonry.
If left unchecked, the situation can worsen, leading to structural instability in the worst cases – such as for homes built at the tops of hills, or on land prone to erosion.
According to figures from Nationwide Building Society, just 8% of householders intend to move in the next 12 months.
However, 47% are planning home improvements, 9% of which are likely to involve structural work as they seek to add extra living space to their property.
Underpinning can help to ensure the stability of structures while work takes place around them – particularly if any excavation is required.
And with mini piling rigs, the heaviest piling equipment can be kept off-site, with compact rigs used instead to minimise disruption and vibration.
Underpinning techniques can protect structures near demolition work
Underpinning techniques can be an important part of the demolition process – not on the building being brought down, but on surrounding structures.
According to newly updated guidance from the Health and Safety Executive, uncontrolled collapse is a major risk during demolition work, and applies not only to the main structure due for demolition.
“The structural survey should consider … nearby buildings or structures,” the HSE advises.
“The method statement for the demolition should identify the sequence required to prevent accidental collapse of the structure.”
In practice, this is one of the fundamental stages in any demolition work, and the HSE adds that structural engineers should assess the entire site before any work is allowed to begin.
Where any concerns are raised about nearby buildings, underpinning techniques may be used to ensure they remain stable from their foundations in the face of any vibrations as their neighbouring structure is brought down.
Underpinning can also restore some strength to structures that have shifted during heavy nearby construction or demolition work – allowing you to make them usable once again if the initial survey did not identify the problem of them becoming damaged.
More weather dismay heightens need for underpinning
Underpinning of foundations remains a likely prospect for buildings of all kinds in areas of the UK, following a month of stark contrast in terms of rainfall.
With heavy rains frequently forecasted by meteorologists, weather warnings for the whole country issued by the Met Office, and images of flooding making the news, you could be forgiven for thinking the deluges have been nationwide.
However, the Met Office has confirmed that, although June was the wettest on record in Wales and Northern Ireland, and for the UK as a whole, it was only the second-wettest in English history, and ranked just eighth on Scotland’s records list.
In certain parts of the north-west UK, it was actually one of the driest months since records began, with a few wet days at the end of the month just tipping the scales past the all-time lows seen by several weather stations.
Either way, it is these extremes of weather – rather than moderate and consistent levels of rainfall and sunshine – that can leave soil either waterlogged, and therefore less stable, or dried out and more prone to crumbling.
For properties in the worst-affected areas, it could be wise to check whether structural stability has held in this year of stark contrast, or whether underpinning methods may be needed to restore strength to foundations.
Continued extreme weather could make underpinning foundations a necessity
The British weather has swung back to being extremely dry and hot in the past few days – which could make underpinning foundations necessary to safeguard some structures.
Recent weeks prior to that have seen heavy rainfall take some areas out of drought conditions, while others languished under storm clouds and a hosepipe ban at the same time, following another heatwave towards the start of spring.
All this means soils have been expanding and contracting repeatedly over the early part of this year, as rainwater swells them and then the heat of the sun dries them out.
In some areas – particularly soils with root networks of trees passing through them – this is likely to have had a destabilising effect, which may put nearby buildings at risk.
Underpinning foundations can help by putting back much-needed stability in places where shifting soil or subsidence has changed the density of the surrounding land.
We can fit pile foundations and needle beams to existing properties, as a combined approach towards supporting the structure with minimal excavation work required.
Underpinning foundations can help in drenched drought conditions
Underpinning foundations could be the solution if this year’s strange weather patterns have left your property standing on less stable ground.
Back in January, we told you about expansive soils – ground that expands or contracts to a large degree due to changes in moisture.
Since then, we have seen an early-spring heatwave that left the country facing drought conditions, followed by heavy rains that have caused disruption for quite the opposite reason.
With many people confused as to why they are subject to a hose-pipe ban when their garden is waterlogged, it’s worth considering what’s happening underground.
That dried-out soil during the highest temperatures of the drought is likely to have contracted in size – with expansive soils shrinking to a particularly large extent.
Now the rains have come, some areas will be swelling back to their fullest, which is likely to cause shifting in the foundations of buildings constructed in expansive soils.
If you suspect your property has weakened as a result of the strange conditions seen so far in 2012, you may want to look into underpinning foundations to help add extra support where it is no longer provided by the surrounding soil.
Underpinning foundations can help ‘naive’ first-time buyers
Underpinning foundations can help to make a property saleable again, if first-time buyers find they have purchased a home that suffers from subsidence.
Research from HSBC indicates that many first-time buyers are “naive” when it comes to buying their first home, and do not ask the most important questions of the vendor.
Just 5% consider subsidence to be something they should ask about – compared with 14% of estate agents who said it is an important question.
Instead, first-time buyers often focus on more general issues like location, garden size and the presence of local amenities – all of which they could find out for themselves, without asking the vendor.
“Buying a home is a serious financial commitment, so it is important that first-time buyers do their homework,” says HSBC’s head of mortgages Peter Dockar.
For those who find their new home is subject to subsidence, but who have already exchanged contracts and keys, underpinning foundations can help to prevent any further slipping of brickwork.
Even in poor ground conditions, we can combine pile foundations with needle beams to offer an extra level of support to a property.
With several types of piling foundations to choose from, contact our pile driving contractors and we can help you to decide which is right for your property.
Underpinning foundations may be necessary after eradicating Japanese Knotweed
You may want to look into underpinning foundations if you have suffered an infestation of Japanese Knotweed close to the structure of your property.
The weed is a significant enough threat that the Royal Institution of Chartered Surveyors has published specific guidance on how to assess the risk it poses to buildings.
The highest threat level – tier four – is reserved for when growth is detected within 7m of conservatories and garages.
In a single season, Japanese Knotweed can spread 7m across the ground, and it can reach a height of 3m in just 10 weeks.
However, its deep roots may present more cause for concern where foundations are involved, as at 3m they can draw water from the ground deeper than many other plants might.
This can leave the underground soil dried out, raising the risk of subsidence – something the new RICS guidance should help surveyors to assess more accurately.
If your surveyor raises concerns during a remortgaging evaluation of your property, you may want to seek advice about underpinning foundations that have been disrupted by Japanese Knotweed, other root systems or simply by soil that has become parched due to excessive drainage and inadequate rainfall.