Bangor sits where the mountains meet the Menai Strait. Elevation shifts from sea level to over 100 metres in less than a mile. That means one thing for shallow foundation design: ground conditions change fast. A site on the High Street can sit on glacial till while a plot 300 metres east hits weathered schist. In our experience, the biggest mistake we see is assuming uniform bearing strata. It rarely happens here. The Ordnance Survey pinpoints Bangor at 53.2277, -4.1269, but the geology underneath that point tells a more complicated story. Getting the bearing pressure right early saves redesign costs later. We pair our shallow foundation design with test pits to verify the top 3–4 metres where footings will sit. Without that visual check, even a tight SI can miss soft pockets left by glacial meltwater channels common across Gwynedd.
In Bangor, the difference between a straightforward strip footing and an expensive ground replacement often comes down to one metre of glacial clay.
Q&A
How much does a shallow foundation design package cost for a typical Bangor residential extension?
For a single-storey extension on a standard Bangor plot, our design package generally ranges from £1,450 to £2,530. The final figure depends on whether we need to commission new test pits or can work from existing site investigation data, and how complex the ground profile turns out to be.
What ground investigation is needed before you can design the footings?
We need at least two exploratory points to 3 metres depth for a house extension. Usually that means machine-dug test pits or window sampler boreholes. If the site is on a slope or near the Strait, we may add a third point to capture the variation. Lab testing on disturbed and undisturbed samples follows. Without this data, any design is guesswork. BS 5930 gives the framework we follow.
How long does the design process take from site visit to final report?
Site work takes one day. Lab testing runs five to seven working days. The design and reporting phase takes another week. In total, expect two to three weeks from instruction to final issue. We can fast-track to ten working days if the structural engineer is waiting to start detailing.
