Decking or Patio: Which Is Better for a Cardiff Garden?
How the two compare on cost, lifespan, grip, slopes and upkeep, and when the Welsh planning rules come into it.
It's one of the first things people ask us on garden visits around Cardiff: decking or a patio? We've built both since 1990, so there's no reason for us to push one over the other. It depends on your garden's shape, how much shade it gets, what you want to spend now, and how much upkeep you'll put up with later.
Customers usually ask us about cost, how long it'll last, whether boards get slippery, what to do with a sloping garden, and the Welsh planning rule that catches out raised decks. If one option is plainly better, we'll say so. If it's just what you like the look of, we'll say that as well.
Is decking or a patio better for a Cardiff garden?
On a flat garden, or one with a gentle slope, we'd usually say a patio is the better bet. It lasts longer, doesn't need much looking after, and copes well with Welsh rain. Decking tends to make more sense on a steep or uneven plot, because it can give you a level area without heavy digging or tall retaining walls. If it could go either way, we'd look at the shade, the budget, and how you'll actually use the space.
Start with the ground. On a level garden, a patio goes on a dug out and compacted base. It'll stay put for decades. Put that same patio on a slope and you've got to cut into the bank, hold the soil back with a retaining wall, then get rid of the spoil. That can double the work. A deck on posts steps over all of that.
Have a look at the light as well. A north facing garden, or one under trees, stays damp for much of the year in South Wales. Both surfaces will grow algae in those conditions. But a textured porcelain patio is easier to keep grippy than timber boards, and it won't rot where the shade keeps it wet.
Think about how you'll use it. If it's taking a heavy table, a barbecue, a hot tub, or people walking back and forth from the back door, a patio is the tougher surface. If you want something warmer and softer for seats halfway down the garden, or a level spot for the evening sun, decking often suits that better.
On plenty of gardens we work on, we put in both: a patio by the house, where the traffic is heaviest, and a deck further down where the ground drops away. Here's how a patio, a composite deck and a timber deck compare.
| What matters | Stone or porcelain patio | Composite deck | Timber deck |
|---|---|---|---|
| Up-front cost | £90 to £140 per m² for natural stone, our guide range | Quoted per job; boards cost more than treated softwood | Quoted per job; often the cheapest way to cover a level area |
| Typical life | Decades on a proper base | Leading brands warrant boards for up to 25 years | Built to last at least 15 years with good timber and care |
| Yearly upkeep | Sweep, wash, top up joints if needed | Wash down a couple of times a year | Clean, then oil or stain every year or two |
| Grip in wet shade | Good with textured outdoor porcelain | Better than smooth timber, still needs cleaning | Can get very slippery once algae takes hold |
| Sloping garden | Needs digging and often a retaining wall | Can be built level on posts | Can be built level on posts |
| Planning in Wales | Ground level patios are usually fine | Over 30 cm high needs permission | Over 30 cm high needs permission |
Is decking cheaper than a patio?
A simple ground level timber deck is often cheaper to build than a natural stone patio of the same size. There's less digging, and no sub-base to bring in. Composite boards and raised decks can close that gap quickly. Our guide range for a natural stone patio is 90 to 140 pounds per square metre, and we price decking per job.
Patio prices are fairly predictable once we know the area. Most of the cost is in the base, digging out, taking the spoil away, laying and compacting the sub-base, then bedding each slab on mortar. That's why we can give a guide range of 90 to 140 pounds per square metre for a natural stone patio.
Decking changes a lot from one garden to the next, so we price it per job, not per square metre.
A low deck on level ground usually needs a simple frame and a weed membrane. A raised deck on a slope is different. It needs posts set in concrete, a stronger frame, steps and usually a balustrade. Each bit adds labour and materials.
Board choice matters as well. Pressure treated softwood boards are the cheapest to buy. Composite boards cost more per board, but you're not buying oil or stain, and you're not spending time putting it on every year or two. Over the life of the deck, the gap narrows.
If you're putting quotes side by side, ask about what's underneath. A composite deck often sits on a pressure treated timber frame, and that frame should be rated for ground contact. The cheap deck usually saves money on the bits you can't see. Those are normally the bits that fail first. Our driveway prices page lists our guide ranges for hard landscaping. A free site visit gets you a fixed written figure for either option.
Which lasts longer, decking or a patio?
A well laid patio lasts longer. Stone or porcelain on a properly compacted base can last for decades, with not much more than cleaning and the odd joint topped up. Good timber decking should last at least 15 years. Some leading composite boards come with warranties of up to 25 years, but it's often the frame underneath that decides when a deck is finished.
Patios usually fail slowly, and there's normally a reason you can trace. A thin base. Slabs laid on dots of mortar instead of a full bed. Water with nowhere to go.
Get the base and the falls right, and the surface itself is close to permanent. Porcelain barely absorbs water, so frost has little to work on. Better sandstones just mellow with age.
Timber decks wear from the bottom up. The Timber Decking and Cladding Association, the industry body, says a deck should be built for a minimum service life of 15 years. That means pressure treated or naturally durable timber, with joists rated for ground contact. Boards left wet in shade, or a frame sat in soil with no air around it, will cut that life short.
Composite boards resist rot because the wood fibres are bound in plastic. Many ranges come with long board warranties too.
But read the small print. A board warranty covers the boards, not the frame they're screwed to. Most also expect the deck to be fitted and cleaned to the maker's instructions.
For lifespan, we look at the whole build. A patio on a proper base will give you many years of use. So will a composite deck on a well ventilated frame rated for ground contact. Our workmanship on either carries the same 25 year guarantee.
Is decking or a patio more slippery in the wet?
In a damp, shaded Cardiff garden, timber decking is usually the most slippery of the three once algae gets hold. Textured outdoor porcelain is usually the grippiest. Good composite boards sit in between. Most slips come from that green film you get in the shade, not the surface on its own. So it needs regular cleaning.
Rain on its own is rarely the problem. It's the thin layer of algae and grime that builds up where the surface stays wet, under trees, along a north facing wall, beside a hedge. In our climate, that can happen within a single wet season.
Smooth timber boards are the worst offenders. People often think the grooves in standard deck boards are there for grip, but once algae gets in them, they don't do much. If you want timber in a shady spot, anti slip inserts help. So does a regular scrub with a stiff brush and deck cleaner.
Composite boards have a textured finish and don't soak up water like timber, so they usually give better grip than smooth timber. They're not magic though. Pollen, leaves and algae still build up, so give them a wash a couple of times a year to keep them safe underfoot.
For a shaded patio, outdoor porcelain with a textured finish is the safe choice. Riven natural stone is a decent second. Our patio materials guide shows which finishes grip best. Whatever you choose, the cheapest anti slip measure is a proper fall so water can run off.
Which is better on a sloping garden, decking or a patio?
On a steep or uneven slope, decking is usually better value. A deck on posts gives you a level area without digging into the bank or building tall retaining walls. On a gentle slope, a patio with a step or a low wall is often neater and lasts longer. Once a deck is more than 30 cm off the ground, Welsh planning rules come into play.
Levelling a slope for a patio means moving earth. We either dig into the bank and hold it back with a retaining wall, or build up the low side and retain that. On a steep garden, it can be both. Every tonne of soil has to be dug out, moved and usually taken away by skip or grab lorry, so the groundwork can cost more than the paving.
A deck works differently. Posts set in concrete footings hold a level frame over the slope, so the ground underneath barely changes. That's why you see raised decks so often on the hillier streets of Penarth, Caerphilly and the Valleys.
The height is the bit to watch. If a deck rises more than 30 cm above the ground, it's no longer permitted development in Wales. A high deck needs guarding as well. As a rule, we fit a balustrade wherever the drop is more than 600 mm. That's the drop where building regulations ask for guarding on stairs, landings and balconies in homes.
On a gentle slope, the sums often point back to a patio. A single step can do it. Or a low retaining wall in brick or block can turn the slope into two level areas that'll outlast any deck. Our guide to retaining walls explains when a wall needs approval, and on a free site visit we can price both options side by side.
Composite or timber decking: which should I choose?
For most Cardiff gardens, we'd go for composite. It doesn't rot, splinter or need staining every year in our wet climate. Timber is cheaper to build and easy to repair. It suits you if you want a natural material and you don't mind looking after it. Whichever boards you choose, the frame underneath needs doing properly too.
Wet weather tends to decide it for you. Timber decking needs cleaning and a coat of oil or stain every year or two to keep water out. Leave it for a few seasons and it'll start to grey, split and grow algae. Composite boards are wood fibres bound in plastic, so they don't take on water. Just wash them down a couple of times a year.
Timber still has its uses. It's cheaper to buy, it doesn't get as hot in direct sun as dark composite can, and if a board gets damaged, you can sand it, plane it or swap it for a standard length from any merchant. It also weathers to a silver grey. Some people like that.
Composite isn't perfect. There are a few catches worth knowing before you choose it. Dark boards can get hot underfoot on a sunny day. Some ranges lighten slightly in their first months outdoors, then settle. Drag furniture across it and scratches can't be sanded out like they can on timber. Felt pads under chair legs are a sensible habit.
Whatever boards you choose, ask how the frame's going to be built. You want pressure treated joists rated for ground contact, air moving underneath, and a weed membrane below. A rotten joist will finish a deck long before the boards wear out.
| What matters | Composite boards | Treated softwood boards |
|---|---|---|
| Up-front cost | Higher per board | Lower per board |
| Yearly upkeep | Wash down a couple of times a year | Clean, then oil or stain every year or two |
| Rot and splinters | Does not rot or splinter | Can rot and splinter if upkeep slips |
| Grip when wet | Textured surface, still needs cleaning | Gets slippery in shade once algae builds up |
| Hot sun | Dark boards can get hot underfoot | Stays cooler |
| Damage | Scratches cannot be sanded out | Sand, plane or swap a board |
| Expected life | Leading brands warrant boards for up to 25 years | Built for at least 15 years with good timber and care |
Do I need planning permission for decking or a patio in Wales?
Usually not. If the deck is no more than 30 cm above the ground, doesn't go beyond the front wall of the house and, with any extensions and outbuildings, covers no more than half the garden, you're normally fine. A ground level patio in a back garden usually needs no permission at all. Listed buildings, flats and some conservation areas are different, so check with your local council.
The Welsh Government's householder guidance treats decking and other raised platforms as permitted development, so you don't need an application, if the conditions are met. The deck can't be more than 30 cm above the ground. It can't go beyond a wall forming the principal elevation of the original house. Count it with any extensions and outbuildings, and it must cover no more than 50 per cent of the garden. If it would sit closer to a highway than the house does, it has to stay at least 5 metres from that highway.
The 30 cm limit is the bit that catches people out, especially on a slope. Your deck might be level with the back door, but it can easily be a metre off the ground at the far end. How height is measured on sloping ground has been argued over at planning appeals. So if any part of the deck gets close to the limit, ask the council before you build.
These allowances are for houses only. Flats and maisonettes don't get them. Permitted development rights can also be taken away by a condition on the original planning permission, or by an Article 4 direction. You see those most often in conservation areas. Listed buildings are different too, as many jobs need listed building consent even when they wouldn't need planning permission elsewhere.
A patio laid at ground level in a back garden is normally permitted development. At the front, the five square metre rule for hard surfaces applies. If an impermeable patio or path is over that size and drains onto the road, it needs permission. If it's permeable, or drains into a border, it does not. Our guide on planning permission covers that rule in detail. Building regulations don't usually apply to a ground level garden deck, but a raised deck or balcony attached to the house can need approval. If yours is high, check with building control.
How much upkeep does each need, and do decks attract rats?
A patio doesn't need much. Sweep it, wash it a couple of times a year, and top up the odd joint when it needs it. Composite decking wants a similar wash. Timber needs that too, plus oil or stain every year or two. Rats do like the dry, sheltered space under a deck, so don't leave food about. Clear debris from underneath and block the easy ways in.
Patio upkeep is mainly keeping algae and weeds out of the joints. For porcelain, a stiff brush and patio cleaner in spring and autumn is enough. Sandstone wants the same treatment, and some people seal it to cut down on staining. A pressure washer is fine on most patios, as long as you keep the nozzle moving and don't blast the jointing out.
Composite decking wants a sweep now and then, so leaves don't sit on the boards. Give it a wash with warm soapy water and a soft brush a couple of times a year.
Timber takes more looking after. You'll need a deck cleaner, a stiff brush, a dry spell, then a fresh coat of oil or stain. Usually every year or two, depending on how much sun and rain it gets.
The rat question comes up on almost every decking visit, and it's fair enough. The space under a deck is dry, dark and sheltered. That's just what they look for, especially if there's a bird feeder, compost bin or barbecue nearby. Food dropped between the boards won't help either.
Keep the space underneath clear of leaves and stored clutter. Don't feed birds over the deck. Close off the sides with skirting boards or fine galvanised mesh, so there's no easy way in. A patio doesn't have this problem, which is another reason some people go for stone or porcelain near the house.
Not sure if yours needs a repair or a full replacement?
Book a free site visit and we will give you a straight answer, backed by our 25-year guarantee and 35 years working with Cardiff and South Wales ground conditions.
Book a free site visit Call 07494 065997Frequently asked questions
Can you lay decking over an existing patio?
Often, yes, if the patio's sound and drains well. A low frame on bearers or adjustable pads can sit straight on the slabs, so you don't have to break them out. The issue is height. The finished deck has to stay well below your damp proof course and the door threshold. If the old patio already sits high, there may be no room for it. We'll check the levels on the site visit before we recommend it.
Should a patio or deck sit below the damp proof course?
Yes. As a rule, the finished surface should sit at least 150 mm below the damp proof course. That's the line of slate, plastic or engineering brick a few courses above the ground. If you build a patio or deck up to it, rain can splash above it and bridge into the wall. That's a common cause of damp inside. If you want a level threshold, you'll need a drainage channel against the house to carry the water away.
Does decking or a patio add more value to a house?
There's no reliable figure for either, so we'd be wary of anyone who gives you one. Buyers usually notice the state it's in. A tidy patio, or a solid clean deck, makes the garden usable and can help the house sell. A rotten, sagging deck can put people off. If you're doing the garden up to sell, a patio is the lower maintenance option to hand over.
Can I have both decking and a patio?
Yes, and in a lot of Cardiff gardens it's the best layout. A patio by the house takes the foot traffic, the table and the barbecue. A deck further down can deal with the slope, or catch the evening sun. Build them together and the levels, steps and drainage can be planned as one job. That usually costs less than doing them years apart.
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