21 Mar The Costs of Underpinning
Perhaps you’re considering having you house, or some other building, underpinned, and wondering how much it will cost. The only simple answer, of course, is that it depends — which is why underpinning firms never give a price list on their websites. There are too many variables to take into account.
A number of factors about the property’s location affects the cost. We have to move equipment and materials to the site, and if it’s hard to get to, or if access to the site is difficult, that will obviously increase the cost. So will the ground conditions, since it makes a much longer and harder job if the ground is waterlogged, or if there are boulders or tree-roots to extract.
The geology, too, will affect not only the difficulty but also the options for underpinning. If the ground is firm just under the surface, for instance, a range of underpinning techniques will be available, such as the mass concrete method, which takes longer but needs no heavy machinery. If the ground is weak several metres down, on the other hand, more secure but machinery-intensive methods will be needed, such as mini-piling or expanding resin injection.
Extent and Loading
It goes without saying that the extent of the structure to be underpinned will affect the cost. Not only will more materials be needed for a larger building, but the job will take longer to complete.
Another important factor is the amount of load the underpinning will have to take. This determines how strong it will need to be and depends not only on the height of the structure, but also on how the load is distributed. It’s impossible to predict the cost until a careful survey has been made.
What’s the Underpinning For?
Underpinning may be required for a number of different reasons, and these will determine what needs to be done and therefore what it will cost. If you want to add a basement, for instance, as long as the quality of the ground is good it may be a fairly simple job.
If, on the other hand, you’re adding more load, such as building another storey, far more substantial foundations may be needed, while subsidence almost certainly implies problems with the ground.
Beyond the technical issues, the cost may be affected by economic factors such as the market and competition, or even how much work we have on. So, if you need to know the cost of an underpinning job, don’t assume we’re hiding something — give us a call on +44 20 8805 4000 and get a quote.