Why floor levels need to be precise

Automated warehouses rely on precision. Technologies such as ASRS autonomous mobile robots (AMRs) are engineered to work within tight level tolerances, far tighter than those most warehouse floors were originally built to.

That means even the smallest misalignment can disrupt the system: wheels and guidance sensors may struggle to track where the AMR should go, the accuracy of picking up or placement may suffer too.

If these issues are left unaddressed, they can become more serious and lead to increased maintenance, unplanned downtime and profit loss. It can also increase the risk of safety incidents for any employees working on the floor. In short, an uneven floor can easily undermine the efficiency of a live warehouse.

How ground movement undermines that precision

Subsidence, differential settlement or changes in soil moisture (particularly beneath clay-rich sites) can all cause warehouse floor slabs to move or settle unevenly. Most facilities currently being retrofitted were not originally designed to accommodate the precise mechanics of the different automation technologies. Older sites or units built on poorly compacted ground are more susceptible to experience gradual slab movement.

The risk of differential settlement or subsidence can be compounded further by several factors:

Racking and mezzanine loads. The point loads from both racking and mezzanine floors puts extra weight on already weakened areas, causing settlement to accelerate further. Uneven flooring can also lead to the misalignment of racking and potential structural issues for the mezzanine.

Drainage issues or changing groundwater levels. Changes in moisture levels can erode or wash away subsoils, causing the above soils to shift or settle unevenly.

Vibration from automated equipment. Continuous vibration or thermal cycling caused by the automated equipment can add further stress to warehouse floors over time.

These processes tend to be gradual, which means they often go unnoticed until the symptoms start to show. This can be in the form of:

• Wide cracks in the floor slabs

• Dips or depressions in the floor

• Misaligned racks

• Standing water in the same area

Why getting a diagnosis first is essential

It may seem quicker and easier to treat an uneven floor as a re-levelling job and fix it straightaway, but this may not fix the underlying cause. Remedying an issue without understanding what caused it in the first place increases the risk of the problem happening again, sometimes within months of costly remedial work. The shrink-swell behaviour of clay soils, poorly compacted ground and drainage issues can all show similar symptoms of ground movement or subsidence but may require different remediation work.

To ensure the right method of repair is used, a thorough ground investigation is needed to understand what’s causing the movement. Using the right method will help ensure the warehouse floor’s longevity and durability. Just investigating the slab itself is not enough to fix the issue.

What are the challenges of remediating a fully operational warehouse?

Warehouses are live, dynamic sites with some facilities operating 24/7. Additionally, unless it’s a new build, warehouses will already have racking installed and conveyor belts in full operation. That means undertaking repairs can be challenging.

Shutting down a facility to complete traditional remedial work such as full slab replacement or extensive underpinning is rarely the best option. Depending on the severity of the ground movement, the cost of disruption to warehouse operations can often outweigh the cost of the remedial work itself. Therefore, any works should be scheduled in phases, ideally during operational hours.

How Mainmark approaches it

Mainmark starts with a thorough investigation of the ground to identify the actual cause of floor movement before any treatment is recommended. That way, warehouse operators can be sure that the solution addresses the underlying problem rather than just treating the surface issue.

Traditionally, warehouse floors are repaired by breaking the concrete slabs out and re-pouring them. That typically requires closing off a large section of the warehouse, often for days or weeks at a time so that the new concrete can cure. This can result in significant downtime.

However, modern engineered solutions such as resin injection take a different approach. Instead of removing the slab, small holes are drilled at calculated points, and an engineered material is injected underneath, filling any voids beneath the slabs and if necessary, re-level the floor.

This and other non-invasive techniques are engineered, targeted alternatives to full underpinning or slab replacement. That means the affected area can be closed off for works while the rest of the warehouse can continue with its day-to-day operations and racking can be left in its place.

In some cases, resin injection can be used in conjunction with JOG computer-controlled grouting. Mainmark combined these two technologies at a 7,706m² business park in Rainham, Essex, where a consolidation of made ground from over 30 years lead to subsidence, seeing up to 208mm of movement in one building. Using these methods, Mainmark managed to re-level three buildings across 3,280m² within two months, keeping all tenants fully operational throughout and without disrupting their trading.

Planning ahead

As more businesses look to increase warehouse productivity through automation, floor integrity should no longer be considered an afterthought. A precisely level floor is essential for safe and efficient operations and it’s vital any ground-related issues are addressed before they become a serious issue.

If you notice any signs of movement or are planning on retrofitting an existing warehouse, arranging a professional ground assessment is an ideal place to start. Contact Mainmark today to see how we can help identify what’s happening beneath your floor and recommend the best next steps.