Groundworks Contractor – What are they and why are they important?

What are groundworks?

Groundworks is a collective name for any part of your building project that breaks the ground. Normally, unless your site needs demolition clearance this involves the first and last stages of site works. In summary the phases of groundworks are:

• Ground investigation.
• Site clearance.
• Substructure and ground stabilisation works.
• Site services.
• Landscaping and reinstatement.

Make sure you invest in a groundworks contractor that has proven experience for your type of build.

Ground investigation

Prior to any building work starting it is normal for local authorities to specify that a ground investigation has to take place. Even if this is not required it is good practice. It is easier to plan actions at the start of a project, rather than have to deal with them later at a greater cost. This can be done by your groundworks contractor.

Typically ground investigations save you money by examining:

• Past land use. This identifies issues like:
  • Ground contamination which can include chemicals and other toxic waste.
  • Old mine workings which can cause ground movement and gas leaks.
  • Buried structures such as cellars, shelters and oil tanks.
  • An archaeology survey may be needed in some cases when there is a known ancient site.
• Ground conditions. This looks at:
  • Geology which is the structure of the ground below the site.
  • Hydrology which is the water above the surface.
  • Hydrogeology which is the water below the surface.
  • Soil condition which examines the soil layers at the surface.
  • Endangered animal protection which is where the habitats of rare species have to be protected.

At the end of the ground investigation phase you will be able to assess the cost of your project. This is because you know the types of foundation that will be required. And any special measures that will be required to treat the identified risks.

Site clearance

Site clearance is the next phase where the site is stripped of topsoil and leveled by your groundworks contractor. This includes forming any retaining walls that are needed to hold the ground in position.

The site clearance will also look to:

• Minimise erosion and contamination.
• Work around any notices that are required by planning. This can include Tree Preservation Orders.
• Secure the site against public and animal access.
• Provide safe vehicle access for the building phase.

Substructure and ground stabilisation works

Substructure is essentially all the elements below the damp proof membrane that supports your building. This includes any:

• Methods of ground stabilisation such as:
  • Soil nails which are metal rods inserted through a plate and fixed in place.
  • Ground and rock anchors which are metal plates attached using steel cables.
  • Geosynthetic materials which are fabrics and membranes that provide reinforcement and sealing properties.
  • Retaining walls which were not part of the site clearance works.
• The foundations that hold your building in place and provide a firm and stable base. These generally can be:
  • Shallow foundations are required where the weight of the building has a low load on the stable soil layer.
  • Deep foundations are required where the load of the building needs to be supported by more stable soil conditions that are found deeper in the ground.
  • Piled foundations are required when extra support is needed due to unstable ground or a very heavy building load.
• Loose gravel infill between the foundations.
• Basement structures built into the foundation layer.
• Concrete screed subfloor below the damp proof layer.
• Trenching to provide access for services to the building.

Services

Groundworks contractors can lay services for the project including:

• Temporary and final drainage. This provides separate systems for sewage and flood.
• Access for the following utilities:
  • Fiber optic and copper phone lines.
  • Mains water.
  • Electricity.
  • Gas.

In some cases a tunnelled system may have to be used to meet planning approval.

Landscaping and reinstatement

It is very common for planning to be granted with a post construction landscaping treatment. This treatment can include:

• The levels and slopes of earthworks.
• Boundary walls, fences or hedging treatment.
• Companion planting for any trees listed in a Tree Preservation Order.
• Final surfaces for access roads, paths and car parking.
• Fulfilling planning reinstatement conditions.

What is typical groundwork equipment?

Although equipment used for groundworks will vary between contractors these will normally include:

• 360 degree excavators.
• 180 degree backhoe loaders.
• Loading shovels.
• Compactor plates.
• Forward tipping dump trucks.
• Ride on and hand driven rollers.

Why is groundworks Important?

As we can see from the different stages of groundworks these are critical to the success of your building project.

Groundworks give you the sound footing and baseline for success. Without ground investigation you are not in a situation where you know your costs. If your site is not correctly cleared and stabilised then any following works will be affected. When the substructure is not accurately set then anything above will not have the proper strength and stability. Poor service provision can lead to expensive rework that can affect the end project result. And finally if the correct landscaping is not achieved the building may never look right in its setting.

Your groundworks contractor must have experience in:

• Drainage systems.
• Foundations.
• Excavation.
• Landscaping.

Select a single contractor to oversee the groundworks phase of the project. This will give you the advantage of:

• Better oversight of the work.
• One key communication point to discuss the project.
• Single responsible contact to be accountable for errors.
• More predictable costs.

It is also key that you make sure your groundworks contractor is familiar with the type of project you are working with. And it is important that they know the site conditions and local planning authority methods. The last thing you want to be paying for is your contractor’s learning curve.

And finally

Never forget that groundworks are the key stage of any construction project. Get the groundworks right and you will control rework and knock-on costs in the rest of the project.

It is also the phase that ensures that your building will perform as designed – not only initially but through its lifespan.