Before the First Paving Slab: The Buried Services That Decide Whether a Redesign Works

The best-looking garden redesign on your street can be quietly undone by things you cannot see. Paving that holds water after every storm. A lighting scheme that never got a cable under the new patio. A shed at the end of the garden with no power, no water and a base that has settled unevenly.

None of these are design failures. They are sequencing failures. So before you fall in love with a paving sample or a plant list, work through the practical infrastructure. It is the least glamorous part of a garden project and the part that determines whether you are still happy with it in five years.

1. Map what is already underground

Start here, always. Water mains, gas, electricity, telecoms and drainage all run through gardens, and none of them care about your new border.

• Check your deeds and any utility plans for easements — a strip of garden with a sewer running through it is not the place for a shed or a deep-rooted tree.
• Use the free online enquiry services before anyone digs, and get a site plan marked up by your contractor.
• Assume nothing about drainage runs. A rodding eye under a shrub is easy to lose and expensive to find later.

Rough cost: nothing, beyond an hour of your time. A private drainage survey with CCTV, if you suspect a problem, runs £150 to £400 and can save you thousands.

2. Solve drainage before you design surfaces

This is the single biggest cause of regret. New paving, a raised patio and a reshaped lawn all change where water goes, and it has to go somewhere legal and sensible.

• Paving should fall away from the house at around 1:60 to 1:80 — enough to move water, not so much that it looks sloped.
• A linear channel drain across a doorway is cheap insurance at £40 to £80 per metre, plus labour.
• Soakaways work well in sandy soil and badly in clay. Size them generously, or plan for a connection to the surface water system where that is permitted.
• On clay, consider a rain garden or planted swale instead of a buried crate you will never be able to inspect.

Rough cost: a new soakaway £800 to £2,000; a channel drain and connection £400 to £1,200.

3. Run power properly, once

Outdoor power is where the shortcuts happen. A spur drilled through a wall and a length of flex is not a garden supply.

• Armoured cable buried 450 to 600mm deep, with marker tape above it, is the standard approach.
• The circuit must be protected by an RCD, and the work should be signed off by a Part P registered electrician with a certificate. Ask for it.
• Specify more sockets than you think you need. Robot mowers, hot tubs, hedge trimmers, festoon lights, a pond pump and a patio heater all want feeding, and they rarely want the same corner.
• Fittings need to be genuinely weatherproof — IP66 or better, with a closing lid.

Rough cost: £150 to £350 per outdoor socket installed; £600 to £1,500 for a proper garden circuit with several points.

4. Route lighting cable before the hard landscaping

Garden lighting is a joy and a nightmare in equal measure, and the difference is entirely in the cabling. If you are laying a patio, decide on lights now.

• Choose between a 230V circuit with individual fittings and a 12V system with a transformer in a shed or garage. Low voltage is easier to extend and safer to live with.
• Decide where the transformer goes while there is still access to a wall.
• Cable needs to reach beds, steps, tree canopies and any wall you might want to wash with light — and a spare route or two costs almost nothing at trench stage.

Rough cost: £15 to £30 per metre for trenching and armoured cable; £600 to £1,500 for a full scheme installed.

5. Get water to where you actually work

One tap by the back door is what most of us have, and it means dragging a hose around the house for the rest of our lives.

• A second tap at the far end of the garden, fed by 25mm MDPE pipe in a trench, is a genuinely transformative upgrade.
• Fit a double check valve to protect the mains supply and an isolation valve so you can drain it down in winter.
• If you are planning borders with thirsty plants, run a buried irrigation line at the same time — installing it later means lifting planting or living with surface hose.

Rough cost: £120 to £250 for a straightforward outdoor tap; £200 to £600 to run a supply to a distant point.

6. Sort storage and structure early

Sheds, bike stores and bin shelters look like an afterthought and behave like foundations. Get them wrong and the whole garden is compromised.

• A firm, level base is not optional. Paving slabs on a compacted sub-base or a concrete raft both work; bare soil does not.
• If the shed is going to house a freezer, a mower charger or a workshop, take power to it during the trenching phase.
• In England, most garden outbuildings fall under permitted development, but check height limits — 2.5m to the eaves is the usual threshold, and stricter rules apply near boundaries and in conservation areas.

Rough cost: £200 to £600 for a shed base; £250 to £700 to extend power or water to it.

7. Trench once, not three times

If you take one thing from this list, take the sequencing. Dig all the trenches — drainage, power, water, lighting — in one pass, before paving, before turf, before the first shrub goes in. Every trade that comes back a second time charges you for the privilege, and every return visit risks the work already done.

A sensible order is: survey, trench and services, drainage testing, hard landscaping, soil improvement and planting, then lighting commissioning, then snagging. Resist the urge to start with the pretty bits.

Questions to ask before you sign anything

• Are you insured, and can I see the public liability certificate?
• Who is doing the electrical work, and will I receive a Part P certificate on completion?
• How will you dispose of waste, and do you hold a waste carrier licence?
• What is the fall on the paving, and where does the water leave the garden?
• Who makes good any damage to existing lawns, fences and planting?
• What is the payment schedule, and how much is held back until snagging is complete?
• What happens if you hit an uncharted drain or cable?
• Can I see the drainage and services plan before work starts?

The rough budget, gathered up

• Services survey and drainage CCTV: £150 to £400
• Soakaway or rain garden: £800 to £2,000
• Channel drainage: £400 to £1,200
• Garden power circuit and sockets: £600 to £1,500
• Lighting installation: £600 to £1,500
• Second outdoor tap: £120 to £600
• Shed base and service extension: £450 to £1,300

Add around 10 per cent contingency and you have a realistic infrastructure budget. It will not be the part of the project you photograph, but it is the part that lets everything above ground do its job — season after season, storm after storm.