How to Prepare a Site for Residential Groundworks

Before You Break Ground: Getting the Paperwork Straight

It is tempting to hire a mini digger and start scraping back topsoil the moment the weather looks kind. Resist that urge. The first day or two of any residential groundworks job should cost you nothing but time at the kitchen table, and it will save you far more than it costs.

Start with your planning permission and any conditions attached to it. Many councils require a drainage and levels plan submitted before work begins, and some insist on a method statement covering how you will protect trees, hedges and neighbouring property. If your house is a new build, check whether the building control body wants a pre-commencement inspection or photographs of the foundation trenches before concrete goes in.

Then think about who else needs telling. Party wall agreements, if you are digging within three metres of a neighbour's foundations and going deeper than theirs, are a legal requirement in most of the UK, not an optional courtesy. Sort them early, because a dispute mid-excavation stops a job dead.

Clear the Area, Not Just the Obvious Bits

Strip the site back further than you think you need to. A working margin of at least 1.5 metres beyond the outer edge of the footprint gives you room to stockpile, stand a ladder, and swing a machine without clipping brickwork that is already up.

• Remove fences, garden furniture, planters, paving and old concrete paths, and stack anything reusable well clear of the dig zone.
• Cut back overhanging branches and grub out shrubs and roots, especially within the root protection area of any tree you are keeping.
• Lift turf cleanly and stack it grass-side-up if you intend to reuse it; it dies quickly if left in a heap.
• Take down bird boxes, cables, washing lines and satellite dishes from gable ends facing the works.

Watch for asbestos cement in old garage roofs, shed bases and soffits. If you are unsure, get it identified before anything is broken. Removal is a licensed job for the bonded stuff, and the last thing you want is fragments scattered across a stripped site.

Mark Every Service Run Before a Machine Arrives

Striking a water main or a buried electricity cable is the single fastest way to turn a two-week job into a two-month one. Order your up-to-date service plans from the relevant utility providers, then book a CCTV drain survey and a cable avoidance tool (CAT) scan across the whole working area.

Plans show you where services ought to be. The scan shows you where they actually are. Treat the two as a pair and never trust one alone.

• Spray-mark routes on the ground in hi-vis paint and drive short timber pegs or pin markers every few metres along each run.
• Note the depth where you can find it, usually by lifting a manhole cover or hand-digging a small inspection pit.
• Hand-dig within 600mm either side of any marked service. It is slow, but a spade is far cheaper than a repair crew.
• Photograph the marked-up ground before you disturb it, and keep the images with your project file.

If the property is connected to mains drainage, locate the existing inspection chambers and record their invert levels. Those levels will govern how your new runs connect, and finding them now avoids nasty surprises when the pipework goes in.

Plan Access for Plant and Muck Away

Work out how a machine gets in, how spoil gets out, and how concrete lorries will reach the trenches. A typical residential job suits a 1.5 to 3 tonne excavator for tight gardens and a 5 to 8 tonne machine where there is proper access. Measure the narrowest point of the route before you order anything.

• Check gate widths, turning circles and any low overhead cables or branches.
• Protect driveways and paving with track mats or a layer of hardcore; repair bills add up quickly.
• Decide where spoil will go. Reuse what you can for backfill and landscaping, and book skips or a grab lorry for the rest.
• Keep a clear route for the concrete wagon within chute reach, or arrange a pump for rear gardens.

Think about neighbours too. A polite note the week before goes a long way when a lorry is idling outside at eight in the morning.

Set Levels, Datum and Drainage Falls Early

Establish a datum point that will not move, such as a mark on an existing manhole cover or a peg driven into firm ground away from the dig. Take all your levels from it with a dumpy level or laser, and write them down.

Foul and surface water drainage relies on consistent falls. As a rule of thumb, 110mm pipework wants a gradient of about 1 in 80, and you should keep runs as straight as possible between chambers. Getting this right at the setting-out stage means foundations, floor levels and garden gradients all agree with each other later.

Finally, have a weather plan. In a wet UK winter, a stripped site turns to soup in a day. Keep a pump, some terram membrane and a stock of clean hardcore on hand, and never leave an open trench overnight without boarding and warning tape around it.