Why Do Interlock Driveways Sink?

Why do Interlock Driveways Sink ? What are the Common Causes of Settlement?

One of the most common concerns homeowners have about interlocking is settlement.

You may have seen an older driveway where some of the pavers are lower than others, or perhaps you already have an interlocking driveways with an area that has started to sink.

This often leads to the question:

“Does interlock always sink?”

The answer is no.

However, interlocking can settle or move when the conditions underneath the pavers change or when the installation was not properly suited to the site.

Understanding what is underneath the pavers is important.

An Interlock Driveway Is More Than Pavers

When you look at a finished interlocking driveway, you mainly see the pavers.

But underneath the surface is a prepared system that includes the existing ground, excavation, base material, compaction and bedding material.

The pavers are only one part of the installation.

If the underlying area is not properly prepared for the site, settlement can occur later.

Poor or Soft Soil Can Cause Problems

Every property has different ground conditions.

During excavation, a contractor may discover areas of soft or unsuitable soil.

If that material remains underneath the driveway, it may not provide the stable foundation required for the project.

At SRT Landscaping, when we encounter poor or soft soil, we try to remove the unsuitable material and replace it with suitable clear gravel.

The exact solution depends on the site.

Insufficient Base Preparation

A driveway carries vehicle traffic, so it requires more preparation than a surface that only experiences foot traffic.

For a new driveway or an extension where the existing base is not suitable, SRT Landscaping typically excavates a minimum of 16 inches, with the actual depth depending on the ground conditions.

The base may include 3/4-inch clear gravel or crushed gravel, depending on the site, followed by HPB as the bedding layer.

The goal is to create a suitable foundation for the finished interlocking surface.

Compaction Matters

Base material needs to be properly compacted.

At SRT Landscaping, according to the site conditions we may use a heavy-duty plate compactor , super duty diesel plate compactor, a jumping jack , and compact the material before moving on to the next material layer.

For example, when clear gravel is used followed by crushed gravel, we compact before adding the next layer. We then compact again before installing the HPB bedding layer.

Proper compaction is an important part of preparing the base.

Drainage and Grading Matter Too

Water can affect the ground underneath an outdoor surface.

That is why drainage and grading need to be considered when planning an interlocking project.

There is no single drainage solution that works for every property.

The existing slope, surrounding landscape, downspouts, soil conditions and other site characteristics can all affect what needs to be done.

At SRT Landscaping, we evaluate these factors as part of the project rather than treating every property exactly the same.

Can an Existing Sinking Driveway Be Repaired?

Often, yes.

One of the advantages of interlocking is that the pavers can be removed from an affected area.

The underlying problem can then be assessed.

Depending on the situation, the area may need to be excavated further, unsuitable material may need to be removed, the base may need to be corrected and the pavers can then be reinstalled.

The appropriate repair depends on why the area moved in the first place.

Simply adding more sand or placing the pavers back on top of an unresolved problem may not address the underlying cause.

Why Some People Blame Interlock

When homeowners experience settlement, it is understandable that they may blame the interlocking material.

But the pavers themselves are not necessarily the problem.

Two driveways can use the same pavers and have very different results if the site preparation and installation are different.

This is why choosing a contractor based only on the lowest price can sometimes lead to disappointment.

The preparation underneath the surface is not something you see once the driveway is finished, but it can make a significant difference to how the installation performs.

What Can Homeowners Ask Their Contractor?

Before installing an interlocking driveway, ask:

• How deep will you excavate?

• What will you do if the soil is soft?

• What materials will you use for the base?

• How will the base be compacted?

• How will grading and drainage be addressed?

• How will the edges be secured?

• What workmanship warranty is provided?

A contractor should be able to explain the installation process clearly.

The Bottom Line

Interlocking does not automatically sink.

When settlement occurs, there is usually a reason that needs to be investigated.

Site conditions, soil, drainage, excavation, base preparation, compaction and installation all need to be considered.

At SRT Landscaping, we approach each project based on the actual property rather than assuming every driveway requires exactly the same preparation.

If you are dealing with a sinking or uneven interlocking driveway in Brampton, Caledon / Bolton, Mississauga or surrounding areas, we can assess the existing installation and discuss the appropriate next steps.