A common mistake we see in Edinburgh is using generic safety factors from textbooks instead of running a proper calculation for the actual ground conditions. The glacial till that underlies much of the city centre behaves nothing like the soft clays found in Leith or the raised beach deposits near Portobello. Without a site-specific factor of safety, you risk either overdesigning the foundation — wasting money — or underdesigning it, which can lead to settlement or even collapse. We run our FS calculations against real borehole data, shear strength parameters, and the exact loading conditions of your structure. That means the number we give you actually reflects what the ground will do under load.
A site-specific FS from real borehole data prevents both overdesign and failure. We calculate yours against actual ground conditions, not textbook values.
Scope of work in Edinburgh
Typical technical challenges in Edinburgh
Edinburgh sits on a mix of glacial till, raised beach sands, and soft alluvial deposits, with groundwater levels that can rise within 2-3 metres of the surface after heavy rain. A factor of safety calculated without considering these conditions is worse than no number at all — it gives false confidence. We've seen retaining walls in the Morningside area fail because the designer used a generic FS of 1.5 for drained conditions when the actual pore pressures were much higher. Our approach is to model the worst credible scenario: saturated soil, seismic loading per UK National Annex to Eurocode 8, and long-term creep in the till. That way the FS you get is the one you can bank on.
Our services
We provide three core FS calculation services tailored to Edinburgh's geology. Each includes field data collection, lab testing, and a certified report.
Slope stability FS calculation
For natural slopes, road cuts, and embankments. We model circular and non-circular failure surfaces using Bishop and Spencer methods, with partial factors from Eurocode 7.
Bearing capacity FS for foundations
Shallow and deep foundations. We calculate ultimate bearing capacity from SPT N-values, triaxial tests, or plate load tests, then apply the required partial factor.
Retaining wall and anchor FS
Overturning, sliding, and rotational stability checks for reinforced concrete walls, sheet piles, and anchored systems. We account for passive pressure and groundwater.
FAQ
What is the typical factor of safety for a building foundation in Edinburgh?
For shallow foundations on Edinburgh's glacial till, we aim for a minimum FS of 2.5 against bearing capacity failure under service loads, per Eurocode 7. For deep foundations, a FS of 2.0 on shaft and base resistance is common, adjusted for the load case.
How much does a factor of safety calculation project cost in Edinburgh?
A typical FS analysis for a small residential project, including field data review and a short report, ranges from £450 to £1,350. Larger commercial sites with multiple slopes or deep foundations can cost more depending on the number of sections and lab tests required.
Why can't I use the same FS number as the neighbouring site?
Soil properties vary significantly even within the same postcode area. The glacial till under Bruntsfield has different shear strength than the same till under Corstorphine due to consolidation history and gravel content. We calculate your FS using your specific borehole data, not a generic value.
What software do you use for FS calculations in Edinburgh?
We use GeoStudio for slope stability, PLAXIS 2D/3D for finite element analyses, and Slide for circular/non-circular failure surfaces. All models are calibrated against laboratory test results from our UKAS-accredited lab.