Retaining Walls near you

This is the rule that separates retaining walls from other garden masonry. Section 167 of the Highways Act 1980 applies to a length of retaining wall any cross section of which is wholly or partly within four yards of a street and which exceeds four feet six inches above the level of the ground at the boundary of the street. Where it applies, no such length of wall shall be erected otherwise than in accordance with plans, sections and specifications approved by the local authority, and where the local authority is not the highway authority it must consult the highway authority. Erecting a wall in breach is an offence liable to a fine not exceeding level three on the standard scale.

There are exceptions written into the section: it does not apply to retaining walls on land used by transport undertakers for their undertaking, nor to walls for the maintenance of which a highway authority are responsible. It is a consent regime that runs alongside planning permission rather than instead of it, so a wall can need both, or need this and not need planning permission at all.

Alongside it sit the permitted development limits that apply to a wall as a means of enclosure: one metre above ground level where it is adjacent to a highway used, or designed to be used, by vehicular traffic, and two metres elsewhere, with no right to increase the height of something that already exceeds those limits. Those rights fall away within the curtilage of a listed building, and in Scotland they are unavailable in conservation areas too. A front garden terraced with a retaining wall beside a pavement can therefore touch three separate controls at once, which is a good reason to ask the council early.

Where the wall is going on the line rather than inside it, a second statute engages. GOV.UK's guidance states that the Party Wall etc. Act 1996 applies to England and Wales and covers a new building on or at the boundary of two properties, work to an existing party wall or party structure, and excavation near to and below the foundation level of neighbouring buildings. A retaining wall can involve all three at once.

Section 1 of the Act deals with building on the line of junction. The building owner must, at least one month before the intended start, serve on any adjoining owner a notice indicating a desire to build. If the adjoining owner consents to a wall astride the line, the expense is defrayed by the two owners in proportions having regard to the use made or to be made of the wall by each of them. If consent is not given, the booklet's summary is that the building owner will be obliged to build the wall wholly on their own land and wholly at their own expense. The booklet also confirms what counts: a party fence wall stands astride the boundary line between lands of different owners and separates them, with a masonry garden wall as the example, and the category does not include wooden fences or hedges.

Excavation is the other trigger, and it matters for retaining work because the foundation for a new wall is often dug close to a neighbouring structure. The Act is separate from planning and from building control, so serving notice satisfies neither of those, and none of it carries across to Scotland or Northern Ireland, which have their own law on relations between neighbouring owners.

A retaining wall is a structure before it is a landscaping feature, and in England Approved Document A covers the loadings on a building and the construction of the structural elements including the foundations and walls. Anything holding back a significant height of ground, carrying a drive or a building above it, or standing where a failure would reach a neighbour or a pavement, deserves a design rather than a rule of thumb, and the specification should say what the wall is assumed to be retaining.

The parts that decide whether it survives are the parts that get covered up. A compacted base of the right depth and material, free draining backfill immediately behind the face rather than the clay that came out of the hole, a filter layer that stops fines migrating into that drainage zone, and a way for collected water to leave through weep holes or a land drain to a suitable outfall. In a British winter the wall is loaded continuously for months, so a drainage path that works only when it is clean and new is a drainage path that will eventually stop working.

Ask where the water goes once it is collected, and get that answer in writing. Discharging behind a neighbour's wall, into a garden that then becomes waterlogged, or into a drain that was never designed for it simply relocates the problem. Ask too about what sits above the wall: a driveway, a parking space or a shed slab adds load that a wall built for a flower bed was never designed to carry.

Water pressure behind the wall is the usual culprit. If the backfill cannot drain, every period of prolonged rain loads the wall with saturated ground, and the effect is cumulative: a wall moves a little, the movement opens paths for more water, and the next wet winter moves it further. Blocked or omitted weep holes, a drainage zone silted up with fines because no filter layer was installed, and a land drain whose outfall has been buried by later landscaping all produce the same symptom.

Surcharge is the second cause. A wall built to retain a garden bed and later asked to hold up a parking space, a shed, a delivery of aggregate or a hot tub is carrying loads outside anything it was designed for. So is a wall whose ground above has been raised by imported topsoil. Movement that begins after a change further up the garden usually has its explanation there.

The third is the base. A footing too shallow, laid on soft or made ground, or undermined by a service trench or a scoured outfall, lets the whole wall rotate rather than push. Trees matter here as well: on shrinkable clay, mature trees close to a wall change the moisture in the ground seasonally, and both the ground beneath the footing and the retained soil can move with them.

A retaining wall that is visibly moving is a structural risk to whatever is above and below it, and that includes people on a pavement or in a neighbour's garden. Keep people and vehicles away from both sides, stop loading the ground above it, and get it looked at rather than watched.

Local authorities have powers here. Under section 77 of the Building Act 1984, where a building or structure, or part of one, appears to be in such a condition, or is used to carry such loads, as to be dangerous, the authority may apply to the court, which may make an order requiring the owner to execute the work necessary to obviate the danger or to demolish the structure and remove any resulting rubbish. Where the danger comes from overloading, the court may make an order restricting its use until it is made safe. If the owner does not comply, the authority may execute the order as it thinks fit and recover its expenses.

That is not a reason to panic about a hairline crack, but it is a reason to treat active movement as something with a deadline attached. It is also a reason to keep any engineer's report, because a purchaser's surveyor will ask about a wall that has obviously been repaired.

Get the specification written down before anyone breaks ground: the height and length, what is being retained and what sits above it, the base depth and material, the wall construction and any reinforcement, the drainage zone and filter layer, the weep holes or land drain and where they discharge, how the excavated material leaves the site, and who is responsible if the ground behind moves during the works. Where the wall is near a street, ask directly whether section 167 approval is needed and who is obtaining it.

Site safety deserves a mention because so much of this work involves wet cement. HSE warns that a serious burn or ulcer can rapidly develop if cement is trapped against the skin, that in extreme cases such burns may need a skin graft or cause a limb to be amputated, that cement can cause chemical burns to the eyes, and that it causes both irritant and allergic contact dermatitis, with some skilled tradesmen forced to change trade because of it. The controls it expects include waterproof gloves suitable for alkaline substances, high top wellington boots when pouring concrete, and hot and cold or warm running water, soap and towels with basins large enough to wash forearms.

To compare contractors, LokalMatch takes the details once. Describe the wall, the height and length, what it is holding back, what you have seen it do and whether it stands near a pavement or a boundary, and retaining wall contractors covering your postcode contact you directly. They pay for the requests they receive; posting one costs a homeowner nothing. LokalMatch does not build walls, does not set prices and does not vet, rank or recommend anyone, so comparing what each contractor proposes to put behind the wall is where your attention is best spent.