People spend weeks comparing colours, styles and finishes. They order samples, browse online and carefully consider how the finished patio will look in their garden. It's exactly what I'd do. What they don't always think about is what's happening underneath.

Yet in my experience, that's often the difference between a patio that still looks great in 20 years and one that starts showing problems after just a few months.

The 80/20 rule

There's a principle we regularly discuss with homeowners and installers alike at Marshalls – what we call the 80/20 rule.

The paving itself typically accounts for only around 20% of the total project cost. The other 80% is everything needed to install it properly.

That includes:

  • Excavation
  • Ground preparation
  • Drainage
  • Sub-base materials
  • Labour
  • Installation expertise
  • Waste removal
  • Finishing details

That's why I often say that a successful project is approximately 80% installer and 20% product.

Don't get me wrong – product quality absolutely matters. A good paving product will perform better and maintain its appearance for longer. But even the best paving on the market can fail if the installation isn't right.

I've seen premium paving products lifted, replaced and re-laid because the groundwork wasn't properly prepared in the first place.

Most failures start below the surface

In my experience, a failed landscaping project is rarely down to the paving itself.

The root cause is almost always hidden underneath. Common issues include:

  • Insufficient excavation
  • Inadequate sub-base depth
  • Poor compaction
  • Incorrect falls
  • Drainage that hasn't been properly considered

The challenge is that none of this is visible once the project is finished.

Everything can look perfect on the day the installer leaves. It's often months or years later that the consequences begin to appear.

What poor groundwork looks like

There are a few common signs associated with failed installations.

  • Sinking paving – often caused by inadequate excavation, poor compaction or missing edge restraints. The result is paving that settles unevenly over time.
  • Standing water – poor drainage design or incorrect levels can leave water collecting on the surface after rainfall, encouraging algae growth and creating maintenance and safety issues.
  • Movement and rocking slabs – unstable foundations beneath the paving can lead to movement, particularly in areas that experience regular foot traffic.
  • Cracking – ground movement beneath the surface places additional stress on the paving, leading to premature cracking and deterioration.
  • Paving installed too close to the damp proof course – incorrect levels can create long-term problems around the property and should always be carefully considered during installation.

In many cases, the only solution is to lift the affected area and start again – an expensive lesson that could often have been avoided.

Every garden is different

One of the biggest misconceptions I encounter is the belief that every patio installation should be carried out in exactly the same way. That's not true.

Every project presents its own challenges. Soil conditions, drainage, slopes, access restrictions, the age of your property, garden orientation, elevation and existing features all influence how a project should be constructed.

My years of hands-on installing experience taught me how to spot and solve potential issues before work even begins. Since joining Marshalls as an assessor, I've seen just how much those early decisions influence the finished result.

That's not something you'll necessarily see in the finished patio, but it's often what determines whether the installation succeeds or fails in the long term.

Why the cheapest quote can become the most expensive

It's smart to compare quotes. Most people do.

But when there's a significant difference in price between contractors, it's worth understanding why.

Ground preparation is often where corners can be cut. Reducing excavation depths, using less sub-base material or rushing preparation work can lower costs initially. That’s usually where corners are cut on the critical 80% of the project.

The problem is that these shortcuts often don't reveal themselves until much later.

I've seen plenty of homeowners secure what looked like a bargain, only to face substantial repair costs a few years down the line. A properly constructed patio isn't cheap, but rebuilding one is usually much more expensive.

The questions every homeowner should ask

Before agreeing to any installation, I recommend asking:

  • How deep will the excavation be?
  • What sub-base material will be used and how will it be compacted?
  • How will drainage be managed?
  • What potential issues do you foresee with my site?
  • What guarantees are provided?

A professional installer should be happy to answer these questions clearly and explain why those decisions matter. It's also why independent accreditation matters. It gives homeowners confidence that the installer has been assessed against recognised standards, rather than relying on promises alone.

Great patios are built from the ground up

The paving you choose defines how your patio looks. But it's the installation that determines how long it lasts. That's exactly why choosing the right installer matters just as much as choosing the right paving. When both come together, homeowners can invest with confidence knowing the project has been built to last.

It’s also why I always come back to the same principle.

A successful project is approximately 80% installer and 20% product.

When you understand that, you make much better decisions about where to invest your budget. Because while everyone notices the beautiful surface, it's the work beneath that ensures your patio stands the test of time.

Written By

Marc King

Marc is a Regional Assessor and his story is rooted in hard work, craftsmanship, and a relentless determination to build something of his own.

Read Marc's full profile here.