Pile Foundations and their Suitability within Construction
As housing developments upon the UK's brownfield sites continues apace the industry has had to adapt and change in order to consider the characteristics of such sites.
As housing developments upon the UK’s brownfield sites continues apace the industry has had to adapt and change in order to consider the characteristics of such sites. And whilst these developments have been gaining in commonality over the past twenty years the challenges that rising costs of excavated material disposal and the viability of piled foundations present continues to act as key concerns for many a house builder, contractor and architect. What’s more these challenges become ever more relevant for those who are constructing low rise housing. To this end this article looks at the landscape of pile foundations, explore their benefits and explain where they serve as a suitable option within construction projects.
Let’s Clear up Misconceptions Surrounding Pile Foundations
It’s an industry understanding that pile foundations generally tend to require less material to construct when compared to traditional trench fills, and as such they can provide cost reductions, as well as construction deadlines and sustainability. However despite these benefits the specific criteria for when piled foundations are to be used can seem somewhat unclear. This lack of understanding, and indeed the lack of resources and information to clear up such poor understanding, is a particular issue that the NHBC Foundation has focussed upon addressing, such as their recent publication upon Efficient Design of Piled Foundations for the Low-Rise has shown. So in this article, with the following sections, we aim to clear up the confusion that surrounds correct design approaches and selection of pile foundations, specifically in relation to the construction of low rising housing.
The Benefits of Pile Foundations
‘Direct savings’: Time and Money
Let’s begin with the many benefits of pile foundations. As a key finding within the report there were highlighted some benefits that went against previous perception, a key such example being that separate design criteria is not required when used for the construction of low rise housing.
Rather the most important factor that affects the foundation of a design is the possible damage that can occur upon the built structure. To this point it goes without saying that fissures and cracks are unacceptable within construction and the governing focus should always be upon the avoidance of potential differential movement (regardless of the foundation choice).
What’s more when avoiding differential movement, piled foundation presents another benefit in the form of less material being required for construction (which consequentially avoids the extensive excavation of ground material). This in itself then serves to speed up construction, all whilst avoiding the high associated costs with waste disposal. These benefits we shall refer to as ‘direct savings’ for the house builder, however there are additional benefits to be considered, with each falling under the umbrella of ‘indirect savings’.
‘Indirect Savings’: Avoiding Deep excavation, Environmental Agency concerns and sustainability
Let’s start with one of the most significant indirect savings that pile foundations can provide, which is the complete avoidance of deep excavation. This can serve to not merely avoid health and safety fears and concerns, but it can moreover address specific concerns of the Environmental Agency, such as the possibility of contaminated groundwater permeating underground water sources (which generally occurs as a direct result of the disruptions caused by foundation building).
This particular point is ever more relevant when constructing upon brownfields sites as contamination can present a real risk and should always be considered by the construction professional in question. To this end their choosing of the correct pile foundation can provide a tangible solution in minimising environmental risk.
What’s more when we consider the ever relevant issue of sustainability we find from the research within the report that pile foundations result in significantly lower embodied carbon than is found with alternative options. This means that the lower waste and reduced need for excavation is not only less costly, but also avoids the penalisation of traditional trench fill foundations by the 1996 Landfill Tax.
Going beyond the construction stage
When looking past the construction stage we find that pile foundations are helpful for ensuring that houses meet the demanding requirements of the Sustainable Homes scheme.
This scheme, which relies upon independent assessors, has been adopted UK wide by increasing number of local authorities in a bid to make housing within the UK greener. Specifications under the scheme encourage ‘Geothermal piles’, which utilise pile foundations along with a ground closed loop heat exchanger. This system then benefits from the subterranean thermal differences to heat the buildings that are based above them.
This is then another way in which pile foundations present an efficient, cost effective solution for the brownfield development, all whilst coming with impressive green credentials.
If you want to discuss pile foundations and how they can be of benefit to you, get in contact with us.
Copyright © Jan 2016