The Slot Block Barrier is a patent pending, site safety barrier exclusively designed and manufactured in the UK. The Slot Block Barrier is the only water filled barrier designed to hold standard 3.5 m ‘Hera's Style’ fencing panels to increase site safety, virtually eliminate trip hazards, and give added stability.

Independently tested by MIRA, the Slot Block Barrier enables standard fence panels to withstand winds up to a maximum speed of 57 mph (ca. 92 km/h). This prevents standard fence panels from blowing over and saves valuable time and money with constant re-erection and damage to site fencing.

heras style fence panels blown over

The Slot Block Barrier is manufactured in standard red and white colours, providing clear demarcation of site entrances and roadways as well as adding additional corporate identity.

When using the Slot block Barrier, contractors dramatically reduce the working footprint on site by an average of 500 mm against a standard fence block.

The Slot Block Barrier can also be used in conjunction with our other Safety Barrier system to provide a comparable half size hoarding system

heras style fencing at balfour beatty

Slot block Plastic Heras Style Fence Bases

Key Features and Technical Details

  • Each block 1.75 m – 2 blocks per 3.5 m set
  • Each block is 380 mm wide
  • Each block is 14 kg when empty
  • Each block is 160 kg when filled – 320 kg per 3.5 m set
  • The ONLY Patent pending water filled barrier made to fit a standard 3.5 m x 2 m ‘Heras Style’ fence panel
  • Standard red/white colours – corporate colours available subject to minimum order quantity
  • Reflective strips can be added for extra visibility
  • Lights can be added for additional visibility
  • Small footprint ideal for inner city projects
  • Tested to a wind speed of 57 mph (ca. 92 km/h) – standard fence panels and block only achieve 17 mph (ca. 27 km/h)
  • Ability to rotate 45 degrees
  • 50 mm drainage point for easy emptying
  • 75 mm water fill point

Heras fencing plastic water filled base

Slot block Plastic Heras Style Fence Bases Advantages:

  • Withstand very high winds.
  • Stable on gradients and uneven ground.
  • Lightweight to transport, but provides a sold base once filled with grey water or sand.
  • Anti-slip as sections lock together and feet do not stick out.
  • Anti-Climb base – a 45 degree slant gives no foothold.
  • Panels can change direction up to an angle of 90 degrees.
  • Different colour’s can be used to clearly demarcate different areas on the construction site, such as deep excavations, pedestrian routes and emergency access routes.
  • Portable – Can be transported around site if required
  • Sustainable as made from recycled materials and can be filled with grey water.
  • Saves time and money re-erecting fence panels and prevents damage.

slotblock fencing around construction site

slotblock with fencing panels by roadside


Vat GB591551821 Company Number 02906480 – 1994
Dun and Bradstreet, Number (581590544)
NATO Code Number (NCAGE KD520)
EORI Number GB591551821000


Merlin Industrial Products @ 2024 Errors and Omissions Excepted


Call 01752 690622 / 0800 0418 650 (UK)