Structures In The Garden
Hardscaping Belfast
On a sloping site the garden is really a set of structures with planting between them. CSW builds retaining walls, terraces and steps that hold.
A Sloping Garden Is A Structural Problem
Belfast is built on hillsides. Go up towards the Castlereagh Hills, out to the slopes above Dundonald or into the streets climbing away from the Lagan and you find garden after garden with a real fall from one end to the other. Those gardens do not have a planting problem, they have a structural one, and the moment somebody wants a level lawn or a usable terrace, the job becomes construction rather than gardening.
That distinction matters because retaining structures are the thing in a garden most likely to fail expensively. A wall holding back two metres of saturated ground is carrying loads that most people badly underestimate, and it fails slowly enough that nobody acts until it is leaning visibly. By then the fix is to take it down and start again.
We are builders as well as landscapers, which is exactly the combination this work wants. Retaining walls, terraces, steps, stone features and the drainage behind all of it, designed so the loads and the water are both accounted for rather than hoped about.
Retaining Walls And Terraces
Holding back a change in level in block, brick or stone, with land drain, free draining backfill and weep holes designed in. Drainage is not a detail here, it is the structure.
Steps And Level Changes
Getting between terraces safely, with consistent risers and goings, generous treads and surfaces that stay usable in the wet. Consistency is what stops people falling.
Stone Features And Edging
Raised beds, seating walls, planters and edging that tie the hard elements together, built in materials that sit with the house rather than fighting it.
Why CSW For Hardscaping
Builders Doing Structures
A retaining wall is construction carrying real load. Having tradesmen who build houses on it is not an upgrade, it is the correct trade.
Drainage Behind Everything
Land drain, free draining backfill and weep holes go in as standard, because water pressure is what pushes retaining walls over.
Levels Taken Properly
A survey rather than an eye. On a sloping site the difference between what you think the fall is and what it is decides the whole budget.
We Say When It Needs An Engineer
Above a certain height and load, a retaining wall wants designing rather than detailing. We flag that rather than quietly building it anyway.
Steps That Are Actually Safe
Consistent risers throughout a flight, because an odd one at the top is where people trip. It sounds obvious and it is frequently ignored.
The Whole Garden
Paving, walls, turf, planting and fencing all in house, so the hard structures arrive as part of a finished garden.
Structures, Heights And Drainage
Hardscaping brushes against three separate sets of rules depending on what is being built and where. This is general guidance for Northern Ireland rather than advice about your garden, and your district council and NI Water are the authorities on your own site.
When A Retaining Wall Is Also A Boundary
This is the overlap that catches people. A retaining wall on a boundary is doing two jobs, and the planning limit applies to the enclosure function regardless of the engineering. Under the Planning (General Permitted Development) Order (Northern Ireland) 2015 a wall, fence, gate or other means of enclosure is permitted up to two metres in height, and only one metre where it adjoins a road or a footpath.
So a retaining wall that also forms the boundary, with a fence on top of it for privacy, can add up to considerably more than two metres of combined height. It is worth measuring the total rather than assuming the retaining part does not count.
- Height is measured from ground level, and on a retaining wall that differs on each side.
- Anything added on top, including trellis or a fence, counts towards the enclosure height.
- Open plan estates and Article 4 directions can remove these rights altogether. Belfast City Council has made Article 4 directions, Malone Park being a published example.
Excavation, Levels And The Sewer
Terracing means moving a lot of ground, and on a Belfast garden that frequently means digging in the vicinity of drainage. Building over or near, or realigning, a public sewer, water main or associated works without NI Water's prior consent is an offence under Article 236 of the Water and Sewerage Services (Northern Ireland) Order 2006.
The protected strip is three metres, or one and a half times the depth of the sewer, whichever is greater. On a terracing job it is not only the finished structure that matters but the excavation itself, because reducing the cover over a sewer changes the loading on it.
- Establish where drainage runs before the excavator arrives, not while it is working.
- A structure proposed within the protected strip should first consider relocating.
- NI Water may require a structural engineer's report at the applicant's expense.
Where Building Control Comes Into It
Freestanding garden structures are not usually a building control matter, and building control in Northern Ireland is administered by your district council under the Building Regulations (Northern Ireland) 2012, with no private approved inspector route.
The picture changes where a hardscaping project includes an actual building, a garden room or a substantial store. Schedule 2 exempts a small detached single storey building not exceeding thirty square metres and at least one metre from a dwelling, road or boundary, or one not exceeding fifteen square metres at least one metre from a dwelling.
- Both the area limit and the one metre distance have to be satisfied.
- A substantial retaining structure supporting or adjacent to a building is a different question and deserves proper design.
- Where a retaining wall could affect a neighbouring property, remember there is no party wall regime in Northern Ireland to resolve it afterwards.
Building Structures That Stay Put
Water Is The Load That Matters
Retaining walls do not usually fail because the soil is heavy. They fail because the soil behind them is saturated, and water in the ground exerts pressure that no amount of extra blockwork will resist if there is nowhere for it to go.
So the drainage design is the wall design. Land drain along the base taking water to a proper outfall, free draining backfill behind the wall rather than the clay that came out of the hole, and weep holes through the face. Do that and a modest wall will hold. Skip it and a heavy one will not.
Foundations And Scale
A retaining wall needs a foundation sized for what it is holding, and on a stepped garden that often means a footing considerably wider than the wall itself. Building on the ground that is already there, without digging down to something firm, is the other common cause of failure.
There is also a point at which detailing stops and design begins. Above a certain height and load, a retaining structure genuinely wants calculating rather than building to a rule of thumb, particularly where it supports a driveway, a building or a neighbour's ground. We will say when we think that point has been reached.
Steps People Do Not Trip On
The most important thing about a flight of garden steps is that every riser is the same height. People climb steps without looking after the first two, and an odd riser at the top of a flight is where falls happen.
On a slope that means setting out the whole flight to divide the total fall evenly, rather than building steps until you run out and making the last one whatever is left. Generous treads and a non slip surface matter too, because a Belfast garden step is wet more often than it is dry.
Materials That Sit With The House
Hardscaping is the most permanent thing in a garden and the most visible in winter when the planting has gone. It is worth choosing materials that relate to the building rather than to a catalogue.
On a red brick Belfast terrace, brick retaining and stone copings read naturally. On a rendered 1960s house, rendered blockwork with a good coping is honest and calm. Where a deliberate contrast is wanted, stone works, and it works best when it is clearly a choice rather than a near miss.
How A Hardscaping Job Runs
Survey The Fall
Levels across the site so the total change is a number rather than an impression. Everything about terracing follows from that measurement.
Locate Services
Where drainage and any public sewer runs, before an excavator is anywhere near it. Terracing changes cover over pipes as well as adding structures.
Check Heights And Boundaries
Whether any retaining structure doubles as a boundary, and what the combined height with anything on top of it comes to.
Design Or Detail
Standard detailing where the loads are modest, and an engineer's design where they are not. We say which rather than leave it ambiguous.
Excavate, Found, Build
Dug to firm ground, footings sized for the wall, then the structure built with land drain, free draining backfill and weep holes as it goes up.
Steps, Surfaces And Planting
Flights set out to consistent risers, terraces surfaced, and the soft landscaping put back so the garden reads as one thing.
Frequently Asked Questions
Why do retaining walls fall over?
Water, not soil. Saturated ground behind a wall exerts pressure that no amount of extra blockwork resists if there is nowhere for the water to go. A modest wall with a land drain, free draining backfill and weep holes will hold. A heavy wall backfilled with the clay that came out of the hole will not.
Does a retaining wall count towards the fence height limit?
If it also forms the boundary, yes, and this catches people out. The Planning (General Permitted Development) Order (Northern Ireland) 2015 limits a wall, fence or other means of enclosure to two metres, or one metre where it adjoins a road or footpath. A retaining wall with a fence on top can easily exceed that combined.
How high can a retaining wall be before it needs designing?
There is no single number, because it depends on what it is holding and what is behind it. Above modest heights, and particularly where a wall supports a driveway, a building or a neighbour's ground, it wants calculating rather than detailing. We will tell you when we think that point has been reached rather than quietly building it.
Can I dig out a terrace if there is a sewer in the garden?
Carefully, and only after establishing where it runs. Building over or near, or realigning, a public sewer without NI Water's prior consent is an offence under Article 236 of the 2006 Order, with a protected strip of three metres or one and a half times the depth. Terracing also reduces cover over a pipe, which changes its loading.
What goes behind a retaining wall?
Free draining material, not the clay that came out of the excavation. Backfilling with the same heavy soil you have just dug puts water directly against the wall with nowhere to go. Free draining backfill, a land drain at the base taking water to a real outfall, and weep holes through the face are what make it work.
Why do garden steps feel unsafe?
Usually because the risers are not all the same height. People stop looking at steps after the first two, so an odd riser, particularly at the top of a flight, is exactly where trips happen. The whole flight has to be set out to divide the total fall evenly rather than built until the ground runs out.
Is hardscaping more expensive than planting?
Considerably, and on a sloping site it is where most of the budget goes. Every terrace needs a retaining structure and every retaining structure needs a foundation and drainage. That is the honest picture, and it is why a design either works with the existing slope or commits properly to changing it.
Do I need building control approval for garden structures?
Freestanding garden structures are not usually a building control matter. It changes if the project includes an actual building. Schedule 2 to the Building Regulations (Northern Ireland) 2012 exempts a small detached single storey building not exceeding thirty square metres and at least one metre from a dwelling, road or boundary.
What if my retaining wall affects the neighbour's ground?
Then it needs discussing with them before it is built, because there is no statutory process here to sort it out afterwards. The Party Wall etc. Act 1996 does not extend to Northern Ireland, so there is no notice, no timetable and no award. A conversation and a dated photographic record beforehand is the sensible substitute.
What materials suit a Belfast garden?
Ones that relate to the house, because hardscaping is what you look at in January when the planting has gone. Brick retaining with stone copings sits naturally against a red brick terrace. Rendered blockwork with a good coping is calm and honest against a rendered house. Stone works best as a deliberate contrast rather than a near miss.
More Landscaping & Garden Design From CSW
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If your garden slopes and you want it usable, get us out to take levels and look at the drainage. That measurement is what makes a terracing conversation real rather than theoretical. No charge for the visit.
- Call us: 07703 433214
- Email: Cswbuild@gmail.com
- Location: Belfast, Northern Ireland