The Route Before the Build: Auditing Site Access Before a Single Order Is Placed

An extension can be designed, specified and priced to the last lintel before anyone asks the question that determines whether it can be built at all: how does the material reach the back garden? In dense UK towns, where the only route to the rear is a side passage barely wider than a wheelbarrow, that question is not administrative. It decides the plant, the programme and sometimes the whole scheme.

An access audit is a short measured survey of the route from the public highway to the working area. It is not a structural survey and it does not replace one. It is a record of physical facts — clear widths, heights, turning space, surface type, drainage covers, overhead lines, boundary features and any legal right to pass — assembled before orders are placed rather than after the first aborted delivery.

Why the route is measured before the design is fixed

Contractors price what they can reach. A scheme that assumes a 3.5-tonne excavator will reach the rear garden, when the side path is 780 mm wide and bounded by a Victorian boundary wall, carries an invisible cost from the outset: smaller plant, more manual handling, longer duration, or a crane lift over the roof. None of these are unreasonable solutions, but each changes the budget. Discovering them in week one is a design decision. Discovering them on the morning the skip lorry arrives is a dispute.

The audit also protects the relationship with neighbours, which in terraced streets is a material asset. A chewed gatepost, a cracked paving slab or a flattened shrub is rarely covered by a polite apology.

The gate line: width, height and the swing

Gate openings are usually the narrowest point on the route, and the least understood. The measurement that matters is not the opening between the posts but the clear dimension once the gate is fully open and held back. Hinges, latches, a dropped post and a gate that will not lie flat can each remove 100 to 200 mm at the precise point where clearance is already tight.

Record, at the gate:

• clear width with the gate secured open, measured at the narrowest point rather than at the posts;
• clear height beneath any arch, pergola or overhanging branch;
• the ground surface at the threshold, including any raised lip, step or gravel bed;
• whether the gate can be temporarily removed, and whether it is listed, within a conservation area, or fixed to a wall of structural significance.

Height deserves the same attention as width. A wheelbarrow passes beneath almost anything; a mixer on a dumper, a stack of insulation or a scaffolding standard may not.

The path itself: length is the easy part

A side passage of 900 mm for 14 metres is a different proposition from the same width for 4 metres, because the route offers no room to correct a line. Measure the narrowest clear width along the whole length, not the widest, and note every obstruction: downpipes, meter boxes, air-brick surrounds, protruding sills, raised manhole covers, planting and stored bins.

Where the passage is bounded on one side by a retaining wall or a neighbour's extension, record that too. Walls do not move, and their presence affects how a load can be angled and how much protection the route needs during works.

Turning space, swept paths and the kerb

A vehicle does not need a corridor; it needs an envelope. The turning movement from road to gate is often the real constraint, and it is where a tape measure and a delivery driver part company. Note:

• the width of the carriageway and whether parking is permitted opposite the gate;
• the position of dropped kerbs, and whether a vehicle can mount the footway lawfully;
• the radius available for a vehicle to swing into the opening;
• sightlines and any street furniture, bollards, lamp columns or cycle racks;
• whether the road is a bus route or subject to parking restrictions that require a suspension or permit.

A site access note should state the largest vehicle that can reasonably arrive and leave without reversing into a junction or over a neighbour's drive. Where the answer is a small flatbed rather than an eight-wheeled skip lorry, that is useful information, not a setback.

Overhead: lines, cables and canopies

Low overhead cables are common above rear accessways and side passages. Their presence affects lorry-mounted cranes, hiab deliveries, scaffold erection and the handling of long materials such as steels and lintels. Record the height of any line above the route and the position of poles or stay wires. Where the clearance is marginal, the practical answer is usually a different delivery method, arranged in advance rather than improvised in the street.

Tree canopies, mature hedges and climbing plants belong in the same section. They are easier to work around when identified early, and easier to protect when the route is known.

Ground beneath: surface loading and drainage

The surface carries the load, and not all surfaces are equal. Block paving laid on a domestic sub-base, gravel over soil, and a paved path above a shallow drain run behave very differently under a tracked excavator or a loaded pallet truck.

Record the surface type along the route, the location of inspection covers, gullies and any soakaway, and the visible condition of joints and edges. Where the route crosses a drain run or a lightweight patio, the contractor may choose tracked rather than wheeled plant, spread the load with plates, or use a conveyor or pump for materials. Each option has a cost, and each is best priced before work begins rather than discovered midway.

The permission no tape measure can grant

Physical clearance is only half of access. A route across a neighbour's land, a shared driveway, a private road or a farm track may be usable in fact but not in law. An access audit should flag where a right of way, easement or informal arrangement needs to be confirmed, and whether the terms restrict vehicles, hours or loads.

Related practical points include whether the local authority requires a skip licence, a parking suspension or a hoarding consent, and whether the property sits within a conservation area where works to a boundary wall or gate may need consent. These are questions for the solicitor, the highway authority or the planning department — but they are questions the survey can identify. Confirming that a right of access exists, and on what terms, is not a measurement task; it is a legal one, and it should be resolved before the programme depends on it.

What the audit produces

A useful access report is a short, plain document: an annotated plan of the route, a schedule of clear widths and heights at each pinch point, photographs with a scale, notes on surfaces and services, and a summary stating the largest vehicle and load that can be accommodated, plus the conditions attached. It should be honest about uncertainty — where a dimension is marginal, say so, and recommend a trial with the contractor before delivery.

Indicative figures for standard plant and deliveries are available from every supplier and should be checked with them directly, since dimensions vary by model and by load. The audit's value is that those figures are then compared against measured facts on site, rather than against an assumption made from the road.

Where the savings appear

Access work rarely produces a dramatic headline, and that is the point. Its return shows up as aborted deliveries that did not happen, gates that were removed and refixed rather than replaced, boundary walls that were not struck by a reversing lorry, and redesigns that were completed in the feasibility stage rather than after the foundations were set out.

For homeowners in particular, the most expensive sentence in a project is often the one spoken at the kerb: it will not fit down there. A morning with a tape measure and a notebook in 2026 is a modest investment against the cost of hearing it.