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Septic tank being installed in an excavated pit | groundworks and drainage in King's Lynn by Humphries Construction
Groundworks · West Norfolk

Groundworks Contractorin King's LynnFoundations, drainage and site prep, done right at the base

Everything above the ground is only ever as good as what's below it. Humphries Construction is groundworks-led: we set out, dig, drain and pour the slab so the trades that follow inherit a job that's square, level and dry, not one they have to fight.

£1M public liability insured Free site survey within 7 days Owner-managed by Jason, 25+ years on the tools
25+
Years experience
£1M
Public liability
7 days
To free survey
3 days
Written quote*
Fixed
Written pricing
Recent groundworks contractor work

Real projects, photographed on site in Norfolk.

Septic tank being installed in an excavated pit | groundworks and drainage in King's Lynn by Humphries Construction
New drainage manhole built into a foul run | groundworks and drainage in King's Lynn by Humphries Construction
Utility ducting laid in an open trench across a site | groundworks and drainage in King's Lynn by Humphries Construction
Compacted hardcore sub-base laid ready for slab or driveway | groundworks and drainage in King's Lynn by Humphries Construction
French drain trench excavated and lined with geotextile | groundworks and drainage in King's Lynn by Humphries Construction
Soakaway crates being installed to manage surface water | groundworks and drainage in King's Lynn by Humphries Construction
New drainage pipe run laid in a trench across a Norfolk site | groundworks and drainage in King's Lynn by Humphries Construction
Inspection chamber built into a new drainage run | groundworks and drainage in King's Lynn by Humphries Construction
Night-time septic tank installation completed on schedule | groundworks and drainage in King's Lynn by Humphries Construction
Service overview

What's involved,
explained plainly.

What it is

Groundworks is the civils stage of any build: site clearance, setting out, excavation, foundations, drainage runs, ducting, oversite concrete and the finished slab. On new builds it's the platform the frame sits on. On extensions it's the foundation, damp course and floor. On driveways it's the sub-base that decides whether the surface lasts 3 years or 30.

Who it's for

Homeowners planning an extension or new driveway, self-builders on a plot, developers running two- to twelve-unit sites, and main contractors who need a groundworks package priced honestly and delivered on time in West Norfolk.

When you need it

As soon as you have drawings, a building notice or full-plans application in with building control, or a plot with services identified. Booking early matters, muck-away lorries, concrete pours and building control visits all have to be coordinated in the right order.

Why professional help matters

Groundworks is where hidden costs and long-term failures start. A poorly compacted sub-base heaves. A shallow foundation cracks. A drain laid to the wrong fall blocks within a year. Getting the civils right first time is cheaper than digging it up later, and it's the stage building control care about most.

Ignore it and…

The cost of
getting it wrong.

Bad groundworks don't show up on day one. They show up two winters later, when the extension floor drops, the drive rocks under a wheel, or the drain backs up on a wet Sunday. By then, the trades that laid it are long gone.

Cracked slabs and floors

Sub-base that wasn't dug to firm ground or wasn't properly compacted moves under load. The finished screed cracks and tile lines split.

Damp and cold bridging

Missed DPC, wrong insulation depth or bad detailing at the wall-to-slab junction lets moisture and cold track straight into the room above.

Drainage failures

Runs laid to the wrong fall, missed rodding points, or unsupported pipe over made-up ground all lead to blockages, subsidence and expensive dig-ups.

Building control refusals

Foundations that don't match the approved detail, or that weren't inspected at the right stage, mean uncovering, redoing and re-inspecting, at your cost.

Common mistakes we see
  • Digging foundations before service positions (gas, water, BT, power) are confirmed
  • Skimping on sub-base depth to save on aggregate and muck-away
  • Backfilling drains with the wrong material and no bedding
  • Pouring concrete in the wrong weather without covers or admixtures
  • Skipping the building control inspection before covering foundations
  • Not setting datum levels before the first spade goes in
Our process

A predictable path
from enquiry to handover.

Talk to Jason
  1. 01

    Free site survey

    the owner walks the plot, checks access, ground conditions, existing drainage and services, and talks you through the sensible sequence of works.

  2. 02

    Written fixed quote

    You get an itemised written quote within 3 working days covering setting out, muck-away, concrete, reinforcement, drainage and reinstatement.

  3. 03

    Setting out & dig

    We set out to your engineer's drawings, confirm datum, and dig foundations or reduced level to the correct depth for the ground you've got.

  4. 04

    Concrete, drainage & slab

    Building control notified at the right stages. Foundations poured, drainage laid to fall, DPC and insulation set, oversite finished ready for the frame.

  5. 05

    Completion & handover

    Site left clean, spoil removed, levels signed off. You get the paperwork you need for building control and, on extensions, your 10-year structural warranty.

Benefits

What you actually get
for your money.

Speed on site

Owner-managed scheduling means muck-away, concrete and building control visits are booked in the right order, no waiting a week for the next stage.

No cold-bridged surprises

Detailing at DPC, insulation and wall junctions is done by tradesmen who understand what has to work above ground, not just below it.

Longer service life

Correct sub-base depth and compaction, plus proper drainage falls, mean the finished slab, drive or patio still performs in 20 years.

Genuinely fixed prices

Written quotes are itemised. Muck-away volumes, concrete grades and reinforcement are stated up front, no mysterious extras once the digger's on site.

Building control ready

We work to your approved plans and call the inspector at the right stages. Foundations aren't covered until they're passed.

One point of contact

the owner personally runs the job. When you call, you speak to the man pricing and managing your groundworks, not a receptionist.

In detail

Materials, methods
and the situations we cover.

Foundation types we install

The right foundation depends on ground conditions, tree proximity, loading and depth to firm strata. We install the type your engineer or building control specifies, and we're happy to talk you through what's likely before you commission drawings.

  • Strip foundations, traditional 600mm+ wide poured strips for most extensions
  • Trench-fill foundations, the standard on shrinkable clay in Norfolk
  • Deep-fill and stepped foundations near trees or on sloping ground
  • Raft foundations where ground conditions demand a spread load
  • Piled foundations coordinated with a specialist piling contractor

Drainage, foul and surface water

Foul and surface water are separate systems and have to be laid, jointed and connected correctly. We install to Building Regulations Part H with the right bedding, falls, rodding access and connections to existing manholes or soakaways.

  • 110mm foul drainage in SN8 clay or plastic to correct falls
  • Rest bends, gullies and rodding eyes at every change of direction
  • Surface water to soakaway crates sized by percolation test, or to existing SW connection
  • Manhole builds, benching and cover levels finished flush
  • Connections into existing systems checked with a CCTV survey where needed

Slabs, screeds and oversite

The oversite is what your final floor sits on. We build it up properly: compacted sub-base, sand blinding, DPM lapped and taped, PIR insulation, mesh-reinforced concrete slab poured to level, ready for screed or a finished power-float.

  • MOT Type 1 sub-base whacked in 150mm lifts
  • Radon protection detailing where postcode requires it
  • Mesh-reinforced C30 or C35 slabs to structural spec
  • Power-floated finish available for garages and workshops

Residential vs. commercial and developer sites

For homeowners, groundworks is usually a single foundation, drainage run and slab for an extension. For self-builders and small developers, it's a full package, setting out, reduced level dig, muck-away, foundations across the whole plot, drainage runs to the highway connection, ducting for services, and the beam-and-block or slab platform. We're comfortable in either mode.

FAQ

The questions
homeowners actually ask.

Straight answers on cost, timelines, guarantees and how the job runs. If yours isn't here, call Jason on 07880 333321.

How much do groundworks cost in King's Lynn?
Groundworks are priced on volume of dig, muck-away, concrete grade, reinforcement, drainage runs and slab detail. Rather than a guess, we survey the site free of charge and comes back within 3 working days with a written, itemised, fixed-price quote so you can see exactly what you're paying for.
How long does a typical groundworks package take?
A single-storey extension foundation, drainage and slab typically takes 2–3 weeks depending on ground conditions and weather. A full new-build plot to oversite is usually 4–8 weeks. Your fixed quote includes a target programme.
Do you handle building control inspections?
Yes. We work to your approved plans, notify the building control officer at the correct stages (excavation, foundation concrete, DPC, drains before backfill), and don't cover anything until it's been signed off.
Are you insured for groundworks?
Yes, we carry £1,000,000 public liability insurance and every tradesperson on site is fully insured for their trade. Certificates are available on request before works start.
What guarantee do I get on groundworks?
Groundworks that form part of an extension are covered under our 10-year structural warranty. Standalone groundworks packages (driveway sub-bases, slabs, drainage) carry our workmanship guarantee, confirmed in writing on your quote.
Do you offer emergency drainage work?
For existing customers, yes, we prioritise blockages and collapsed drains. For new enquiries, call 07880 333321 and we'll advise honestly whether it's a job for us or a specialist drain-jetting contractor.
How quickly can you start?
Free survey within 7 days, written quote within 3 working days of that, and typical start on site is 4–8 weeks from contract signing depending on the season and current workload.
Do you work outside King's Lynn?
Yes. Our regular working area covers King's Lynn, Downham Market, Swaffham, Fakenham, Hunstanton, Wisbech, Dereham and Norwich. Anything within roughly an hour of East Winch we'll happily survey.
Can you take away the spoil?
Yes. Muck-away is included in the itemised quote, you know the volume, the tipping cost and the number of loads before we start. No surprise removal charges.
Next step

Get groundworks priced properly, once.

Free site survey within 7 days. Written, itemised quote within 3 working days. Owner-managed by Jason personally, no call centre, no middlemen.

Related services

Works well with

Foundations & FootingsNew Build GroundworksExtensionsDrivewaysNot sure which service you need? Ask Jason.
Call Jason Free Quote