Most of Gerrards Cross went up in one long rush after the railway arrived in 1906. Big Edwardian villas and solid inter-war houses set well back on generous plots, screened by mature oaks and beeches, along quiet roads off Bulstrode Way, Marsham Lane and the Oxford Road. Lovely to live on. Awkward to dig on. A hundred-year-old house, big trees tight to the works, a private road never built for muck-away lorries. Every bit of that is workable. It just has to be settled on paper first, weeks before anything with tracks pulls up outside.
The ground under Gerrards Cross
The village sits on chalk, but you rarely dig straight into it. Across most of the high ground the chalk wears a cap of clay-with-flints, stiff reddish-brown clay packed with angular flint. A few metres of it is the usual expectation, and that is what the British Geological Survey’s Beaconsfield sheet reports. But the survey is careful to add that the depth swings about, because the chalk it lies on was never a flat surface to begin with. Where rainwater has eaten a hollow down into that chalk, the clay follows it in: a solution pipe recorded a few miles from here, at Slade Oak Lane, ran to 37.5 metres. Old river-terrace gravels are about as well. The survey names one local deposit the Gerrards Cross Gravel. Each sits differently under a footing, which is why a trial pit tells you more about your own garden than any map ever will.
THE GROUND HERE
- Clay-with-flints is a shrinkable clay. With big trees near a new extension, foundation depths get set around the trees, sometimes deep enough that trench fill or piling is worth pricing against. Our foundations guide explains how.
- Clay does not take water away willingly. Where the cap thins and the chalk comes up, soakage improves sharply. But that gets proved on the plot, not assumed from the road.
- Flint is abrasive, and abrasive ground eats time. Better that shows up in the programme than in week two.
Trees, consents and private roads
Two conservation areas sit over the heart of Gerrards Cross, the Common and the Centenary area, with a clutch of listed buildings inside them. In a conservation area, works to trees generally need six weeks’ notice to the council, and plenty of trees outside the boundaries carry preservation orders of their own. It’s worth checking with the local planning authority before any tree is touched or a new drive is set out. We’d rather build that check into the early paperwork than trip over it mid-project.
Then there are the roads themselves. The private estates around Camp Road and Dukes Wood, and the gated drives off them, are maintained by the people who live on them, so a kerb cracked by a grab lorry is a bill for the residents, not the council. That changes how a job is set out. Weight and turning circles come first, the gate decides the machine rather than the other way about, and verge protection goes down at the start of the week instead of being argued over at the end of it.
Chalfont Common, north past Chalfont St Peter, is a different flavour of the same ground. Detached family houses rather than gated estates, with the same clay-capped chalk under the gardens and the land tipping away towards the Misbourne valley. Softer setting, same three questions: what is down there, what is growing next to it, and how does a lorry get in and back out.
Extension, basement or new drive. Anywhere in SL9 the awkward parts are the ground, the trees and the way in, and all three are far cheaper to sort out on paper than in a trench. Ask us for a quote and that is where the conversation starts.
We work the villages and towns around here on much the same ground.
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