Patio and Path Groundwork in North Devon: How to Build a Base That Stays Level
A patio looks like the easy end of garden work in Ilfracombe. Lay some slabs, sweep in some sand, put the chairs out. Yet patios are among the most common things we are asked to lift and redo, because slabs rock, corners sink and water runs towards the back door. Almost every one of those problems starts below the surface.
This guide explains how a patio or garden path is built properly: the excavation, the sub base, the falls, the drainage and the surface. It also covers what changes on North Devon's sloping, damp and often clay heavy gardens. Crabb Contractors Ltd has been preparing ground around Ilfracombe since 1962, and the groundwork is the part we are known for.
Quick Answer: What Does a Patio Base Need?
Short answer: A lasting patio or path needs the topsoil and soft ground removed, a compacted layer of crushed stone, a bedding layer, a gentle fall of about 1 in 80 away from the house, edge restraints, and a plan for where rainwater goes. Skipping the compacted sub base is the main reason paving sinks.
Typical build up, from the ground up
Layer | Purpose | Typical detail |
Subsoil | Firm natural ground | Soft or organic soil removed |
Geotextile (where ground is soft) | Stops layers mixing | Laid before stone |
Compacted sub base | Spreads load, drains | Crushed stone, laid and compacted in layers |
Bedding layer | Holds paving level | Sharp sand or mortar bed, depending on surface |
Paving | The finished surface | Porcelain, sandstone, concrete, block or stone |
Joints | Locks paving together | Jointing compound or kiln dried sand |
The right depths depend on the paving and what will stand on it. A path for walking is lighter than a patio that takes a heavy table, a hot tub or an occasional delivery vehicle.
Planning the Patio: Where, How Big and Which Way
Good groundwork begins with a plan, before any digging.
Position. Think about sun, shelter and views. A south or west facing patio gets evening light, but on an exposed Ilfracombe hillside, wind can matter more than sun. A patio close to the house is the most used, and a level doorway threshold makes it far safer.
Size. Make it larger than you think. Most people regret a patio that is too small for a table, chairs and room to move.
Levels. The finished surface should sit at least 150mm below the damp proof course of the house, so rain splash cannot bridge it and cause damp. It should also fall slightly away from the building.
Access. Think about how machinery, materials and waste will get in and out. A narrow side passage changes how much a mini digger can do, and how much has to be moved by hand.
Services and trees. Check for drains, manholes, cables, pipes and tree roots before you finalise the layout.
Falls: The Small Slope That Matters
A patio must never be dead flat. Water needs to run off, or it will pool, freeze, grow algae and seep towards walls.
A typical fall is about 1 in 80, which is roughly 12mm for every metre. It is too gentle to notice underfoot but enough to move water. The fall should run away from the house and towards a lawn, border, gully or drain.
On a sloping garden, the natural fall may already be steeper than that. In that case the patio is often cut into the bank or built up with a retaining wall, so that it sits flat enough to use.
Our guide to retaining walls in North Devon explains how those walls are designed and drained, and our article on sloped and uneven gardens in North Devon shows how a whole garden can be levelled in stages.
Step by Step: How a Patio Is Built
Step 1: Set Out and Mark
Pegs and string lines mark the corners and edges. Finished levels are worked out from a fixed point, usually the door threshold, and the fall is built into the string lines from the start. Good setting out saves hours later.
Step 2: Dig Out
The area is stripped of turf, topsoil and roots, then excavated to the depth needed for the sub base, bedding and paving together. Soft, organic or wet soil is removed until firm ground is reached. Never build over topsoil, because it compresses and rots.
For a small path, hand digging is fine. For a patio, a mini digger is faster, more accurate and kinder on your back. Our digger hire with driver service is often used for exactly this, because an experienced operator can dig to a precise level in a tight garden. Our guide to excavation for driveways and groundwork explains how depth and ground conditions are judged.
Step 3: Deal with the Spoil
Digging a patio creates more soil than most people expect, since the ground is fluffed up when it is dug. A typical patio can produce several tipper loads. Some can be reused to level borders or lawns, and the rest needs removing. Our article on muckaway services in North Devon explains how this works, and why a licensed waste carrier matters.
Step 4: Compact the Formation
Once at depth, the bare ground is levelled and compacted with a plate compactor. Soft patches are dug out and replaced. If the ground is generally weak, a geotextile membrane goes down before the stone.
Step 5: Lay the Sub Base
Crushed stone is spread in layers, usually no more than 75 to 100mm at a time, and each layer is compacted before the next. This builds a firm, free draining base that will not settle. Edges need as much compaction as the middle, because that is where failure often starts.
Step 6: Edge Restraints
Patios need firm edges, or the paving slowly spreads and loosens. Edge restraints are usually concrete haunching with a kerb or edging, or the line of a wall or building. On paths and block paved areas, they are essential.
Step 7: Bedding Layer
What goes under the paving depends on the type.
Sharp sand bed for many block and some slab surfaces. It is screeded level, and the paving is tapped down into it.
Mortar bed for natural stone and porcelain, often a full bed with a bonding slurry to the back of each slab, for strength and to stop water entering underneath.
Grit sand or fine stone for permeable block paving.
Spot bedding, where mortar is dabbed in five blobs under a slab, is quick but leaves voids that fill with water, rock, and crack. A full bed is better.
Step 8: Lay the Paving
Paving is laid from a fixed line, checked constantly with a straight edge and spirit level, and tapped to its final height. Cuts are made at the edges, around drains and at curves, ideally with a proper saw and dust control.
Step 9: Joint and Finish
Joints are filled with a suitable compound, polymeric sand or kiln dried sand, and the surface is brushed clean. Let it cure as instructed before use.
Choosing a Surface
The surface decides how the patio looks and behaves, but not whether it stays level. That depends on the groundwork. Even so, some surfaces suit some sites better.
Porcelain. Hard wearing, stain resistant and low maintenance, with a crisp modern look. It needs a careful, full mortar bed and the right primer. It can be slippery if the finish is smooth, so check the slip rating.
Natural sandstone. Beautiful and varied, widely used in Devon. It can be uneven in thickness, which means more care when laying, and some types stain or hold moss in shade.
Concrete slabs. Hardy and simple, available in many styles, including ones that imitate stone. Colours can fade over time.
Block paving. Flexible, and easy to repair, with a good choice of patterns. Our guide to block paving repair, cleaning and sealing in North Devon shows how to look after it.
Gravel with a grid. Informal, free draining and quick. A stabilising grid stops it moving underfoot.
Resin bound. A smooth, seamless finish, permeable when laid correctly on the right base. See our comparison of resin bound and resin bonded surfaces.
Decking. A lighter option for sloping or awkward plots, though it is a different build and not paving groundwork.
Garden Paths: Same Rules, Lighter Build
A garden path carries less weight than a patio, but it follows the same principles.
Dig out topsoil and soft ground.
Lay a compacted stone base, usually thinner than for a patio.
Install edge restraints, particularly on slopes.
Lay bedding and surface with a slight cross fall for drainage.
Make it wide enough for a wheelbarrow or wheelchair, which is usually at least 900mm to 1.2m.
Paths on a slope need extra care. Steep paths become slippery in the wet, so choose a textured surface and add steps where the gradient is too much. Steps need solid foundations, and often use a retaining wall as a side support. Steps and landings should be built with consistent risers and treads, because uneven steps are one of the biggest trip hazards in a garden.
Drainage for Patios and Paths
Water management separates a patio that lasts from one that fails.
Fall away from buildings. The simplest drainage is a gentle fall onto a lawn or planted border.
Channel drains. A linear drain at the base of a door or the low edge of a patio catches water and sends it to a soakaway or drain.
Gullies. Used where water gathers in a corner or at a low point.
Soakaways. Where there is no drain to connect to, water can go to a soakaway if the ground allows. Our guide to soakaway and land drainage installation in North Devon explains testing and siting.
Permeable build ups. Some patios use permeable paving over an open sub base, so water soaks through and is stored then released. This helps with planning rules on large hard areas at the front of a house.
For a wider look at how groundwork and water fit together, see our article on groundwork and drainage in North Devon.
Planning Permission for Patios and Paths
Most garden patios do not need planning permission. Some limits apply.
A raised patio or platform over about 300mm above ground level can fall under the rules for outbuildings and raised platforms, and may need permission.
In conservation areas, and for listed buildings, extra rules can apply.
Paving a front garden with an impermeable surface over 5 square metres needs either permeable materials or drainage within the property. Our guide to driveway planning permission and dropped kerbs in Devon explains the rule.
If you are unsure, check with North Devon Council before work starts.
Common Patio Problems and What Causes Them
Problem | Likely cause |
Rocking or loose slabs | Spot bedding, poor base, no compaction |
Sunken areas | Soft ground, topsoil left in, poor compaction |
Water pooling | No fall, wrong levels, blocked drain |
Water running to the house | Fall in the wrong direction, no channel drain |
Cracked slabs | Voids underneath, heavy load, movement |
Moss and algae | Shade, damp, no sun, poor drainage |
Weeds in joints | Poor jointing, sand washed out |
Edges moving | No restraint, poor haunching |
Many of these can be fixed by lifting and relaying the affected area on a proper base. Others point to a drainage fault that must be solved first.
Working with the Weather and Seasons
Wet ground makes digging heavy and compaction hard, and frost damages fresh mortar and jointing. In North Devon, late spring to early autumn is the most reliable window, but good contractors are booked ahead. Our guide to the best time of year to book a driveway or groundwork project in North Devon explains how to plan around it.
Patios Next to Garages, Sheds and Outbuildings
A patio often sits beside another structure. Where that building has a concrete base, the levels of patio, base and door threshold have to work together. Our guide to concrete bases for garages, sheds and extensions explains how bases are built, which helps when you plan a patio that joins one.
DIY or Professional?
A small path or a simple patio is a reasonable project for a capable DIYer with time and help. The groundwork is hard physical work, and getting levels right takes patience.
DIY is realistic when:
The area is small, flat and clear of services
The ground is firm and drains well
You can hire a plate compactor and arrange waste removal
You have helpers for lifting slabs
Call a professional when:
The garden slopes, or the patio needs retaining walls
The ground is clay, soft or wet
There are drains, cables or manholes in the way
The patio is large, or carries heavy loads
You want it done in a few days with a guaranteed finish
Our groundwork contractors can do the excavation and base, and our brick paving and driveways team can lay the surface, so one firm is responsible from the first dig to the last joint.
Checklist Before You Start
Where will the patio sit, and how large should it be?
Is the finish level at least 150mm below the damp proof course?
Which way will water fall, and where does it go?
Have you checked for drains, cables, pipes and roots?
How deep will you dig, and what happens to the spoil?
Is the sub base compacted in layers?
Are edges restrained?
Is the bedding a full bed, not spots?
Is there a drain, channel or soakaway where needed?
Have you checked planning rules for raised or front garden areas?
Related Guides From Crabb Contractors
Keep reading: our guides to driveway planning permission and dropped kerbs in Devon, block paving repair, cleaning and sealing, building a concrete base for a garage, shed or extension, soakaway and land drainage installation, retaining walls for sloped North Devon gardens, tarmac driveway repair and resurfacing, farm and equestrian groundwork. For help on site, see our groundwork contractors, brick paving and driveways and digger hire pages.
Frequently Asked Questions
How deep should I dig for a patio?
Usually enough for around 100mm of compacted sub base, 30 to 50mm of bedding and the thickness of the paving. The exact depth depends on the surface and the ground.
What slope should a patio have?
About 1 in 80, falling away from the house. That is roughly 12mm per metre, enough to shed water without feeling sloped.
Do I need a sub base under patio slabs?
Yes. Laying slabs straight onto soil or sand leads to sinking, rocking and cracking. A compacted stone sub base is the foundation of a lasting patio.
Can I lay a patio on clay soil?
Yes, but clay holds water and moves. It needs a thicker sub base, good drainage and sometimes a geotextile layer, so water does not soften the ground underneath.
Do I need planning permission for a patio?
Normally not, unless it is raised more than about 300mm, is in a conservation area, or is a large impermeable surface at the front of the house.
Can Crabb Contractors prepare the ground for a patio in Ilfracombe?
Yes. We excavate, remove spoil, build the sub base and drainage, and lay patios and paths across Ilfracombe and North Devon.
Build the Base First, Enjoy the Patio for Years
A patio is mostly invisible work. The depth you dig, the stone you compact, the fall you set and the drain you add decide whether the finished surface stays flat and dry or turns into a lumpy puddle. Do the groundwork well, and almost any surface will look good and last.
If you are planning a patio or path in Ilfracombe or anywhere in North Devon, call Crabb Contractors on 01271 500072 or get in touch online. We will visit, read the ground and tell you what the base needs before a single slab is ordered.
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