Warning Signs

Construction Warning Signs alert workers, contractors, visitors and members of the public to potential hazards commonly found on building sites and temporary work areas. Also known as site warning signs, hazard warning signs or construction hazard signs, they play a vital role in reducing risk and improving site safety.

Widely used by contractors, developers, principal contractors, local authorities and facilities managers, these signs help identify dangers such as moving vehicles, excavations, overhead work, hazardous substances and restricted access areas.

Typical installation locations include site entrances, perimeter fencing, hoardings, access routes, excavation zones, loading areas, scaffolding locations and high-risk work areas.

Manufactured in the UK and available in durable materials suitable for indoor and outdoor use, construction warning signs provide clear visual communication to help maintain safe and compliant construction environments.

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There are 75 products.

Warning Construction Site Keep Out Sign

Clearly warns people of a construction site and instructs them to keep out, helping prevent unauthorised access to hazardous work areas.
• Warns people of a construction site and instructs them to keep out
• Suitable for construction sites, renovation projects, perimeter fencing and work areas
• High-contrast colours, bold text and clear symbols provide quick recognition
• Available in Aluminium Composite (3mm), Rigid Plastic (1mm), Rigid Plastic (2mm), Self Adhesive Vinyl and Recyclable Correx ® (4mm)
• Helps reinforce restricted access controls and reduce entry into hazardous work areas

£6.86

Warning Construction Site Keep Out Signs - Pack of 10

Clearly warn unauthorised persons to keep out of active construction areas with this Warning Construction Site Keep Out Signs - Pack of 10.
• Warns of construction site hazards and restricts unauthorised access
• Ideal for construction sites, building projects, roadworks and work zones
• High-visibility warning and mandatory symbols provide excellent recognition
• Available in Rigid Plastic (1mm) and Recyclable Correx ® (4mm)
• Supplied as a pack of 10 for consistent site safety and perimeter control

£193.42

Warning Construction Site Keep Out safety sign with warning and mandatory symbols

Warning Construction Site Keep Out Sign

Warn of construction site hazards and prevent unauthorised access with this Warning Construction Site Keep Out Sign.
• Clearly communicates restricted access and instructs unauthorised persons to keep out
• Ideal for building sites, development zones and hazardous work areas
• High-visibility yellow, black and blue design ensures clear recognition and readability
• Available in Rigid Plastic (1mm) and Rigid Plastic (2mm)
• Helps prevent unauthorised entry and improves overall site safety

£9.83

Warning deep excavations safety sign with hazard symbol

Warning Deep Excavations Sign

Warns of deep excavation hazards to prevent accidents and ensure site safety
• Alerts workers and visitors to the presence of deep excavation risks
• Ideal for construction sites, civil engineering projects, and groundwork areas
• Bold black text on yellow background ensures high visibility
• Available in Rigid Plastic (1mm) and Self Adhesive Vinyl
• Helps reduce risk of falls and supports safer working environments

£4.88

Danger High Voltage Electrical warning safety sign with electrical hazard symbol

Danger High Voltage Electrical Sign

Warn individuals of dangerous high voltage electrical hazards with this Danger High Voltage Electrical Sign.
• Alerts people to the presence of high voltage electrical hazards
• Suitable for electrical rooms, substations, switch rooms and industrial environments
• High-contrast yellow and black design ensures clear visibility and instant recognition
• Available in Rigid Plastic (1mm), Rigid Plastic 1mm (Self Adhesive Back), Rigid Plastic (2mm), Rigid Plastic 2mm (Self Adhesive Back), and Self Adhesive Vinyl
• Helps reduce the risk of electric shock and improve workplace safety compliance

£2.71

Tree Protection Area Keep Out Sign

Clearly identifies a protected tree area and instructs people to keep out, helping prevent damage and reinforce site protection requirements.
• Clearly marks protected tree zones and restricts access to the area
• Suitable for construction sites, development projects and protected land areas
• High-visibility yellow background with clear black text provides easy recognition
• Available in Rigid Plastic (1mm), Rigid Plastic (2mm), Self Adhesive Vinyl and Recyclable Correx ® (4mm)
• Helps protect trees by reinforcing restrictions within designated protection areas

£10.20

Warning Beware Of Moving Vehicles safety sign for industrial and warehouse traffic areas

Warning Beware Of Moving Vehicles Sign

Warning Beware Of Moving Vehicles Sign alerts pedestrians and workers to the presence of moving vehicles in busy industrial and workplace environments.
• Warns individuals about moving vehicles and traffic hazards
• Ideal for warehouses, loading bays, construction sites, and industrial areas
• High-visibility yellow and black warning design ensures clear recognition
• Available in durable Rigid Plastic (1mm) and Self Adhesive Vinyl
• Helps improve site safety and reduce the risk of vehicle-related accidents

£6.86

Warning Men Working Overhead safety warning sign

Warning Men Working Overhead Sign

Warn individuals of overhead work hazards with this highly visible warning safety sign designed to improve workplace safety awareness.
• Alerts people to overhead work hazards
• Suitable for construction sites, warehouses, and industrial areas
• High-visibility yellow background with bold black text and symbol
• Available in Rigid Plastic (1mm), Rigid Plastic (2mm), and Self Adhesive Vinyl
• Helps maintain safety awareness in active work zones

£8.10

Danger Drop Below warning safety sign with fall hazard symbol

Danger Drop Below Warning Sign

Warn individuals of dangerous drop hazards with this Danger Drop Below Warning Sign.
• Alerts individuals to the risk of a drop below and potential fall hazards
• Suitable for construction sites, warehouses, elevated walkways, platforms and hazardous edges
• High-visibility yellow and black design provides excellent recognition and readability
• Available in Rigid Plastic (1mm), Rigid Plastic 1mm (Self Adhesive Back), Rigid Plastic (2mm), Rigid Plastic 2mm (Self Adhesive Back), and Self Adhesive Vinyl
• Helps improve awareness around exposed edges and reduce the risk of falls

£2.71

Danger High Voltage No Admittance Authorised Personnel Only safety sign with electrical hazard and prohibition symbols

Danger High Voltage - No Admittance Authorised Personnel Only Sign

Warn of high voltage hazards and restrict access to authorised personnel only with this highly visible combined danger and prohibition safety sign.
• Clearly warns of electrical danger and restricted access
• Ideal for plant rooms, electrical areas and restricted zones
• High-visibility yellow, black and red design for clear recognition
• Available in Aluminium Composite (3mm), Rigid Plastic (1mm), Rigid Plastic 1mm (Self Adhesive Back), Rigid Plastic (2mm), Rigid Plastic 2mm (Self Adhesive Back) and Self Adhesive Vinyl
• Helps prevent unauthorised entry and reduce the risk of electrical injury

£4.88

Danger Fragile Roof warning safety sign with fragile roof hazard symbol

Danger Fragile Roof Sign

Warn personnel of roofing hazards with this Danger Fragile Roof Sign.
• Warns of fragile roof hazards to help prevent falls and serious injury
• Ideal for construction sites, industrial buildings, maintenance areas and roof access points
• High-visibility yellow and black design ensures clear recognition and readability
• Available in Rigid Plastic (1mm), Rigid Plastic 1mm (Self Adhesive Back), Rigid Plastic (2mm), Rigid Plastic 2mm (Self Adhesive Back), and Self Adhesive Vinyl
• Helps improve safety awareness and restrict access to hazardous roof areas

£4.88

Caution Change In Floor Level warning safety sign with yellow hazard symbol

Caution Change In Floor Level Warning Sign

Warn people of uneven or changing floor levels with this Caution Change In Floor Level Warning Sign.
• Alerts individuals to uneven or changing floor levels to help prevent trips and falls
• Suitable for workplaces, warehouses, offices, entrances and public buildings
• High-visibility yellow and black design ensures clear recognition and readability
• Available in Rigid Plastic (1mm), Rigid Plastic 1mm (Self Adhesive Back), Rigid Plastic (2mm), Rigid Plastic 2mm (Self Adhesive Back), and Self Adhesive Vinyl
• Helps reduce trip hazards and improve overall workplace safety

£2.71

Showing 1-12 of 75 item(s)

Construction Warning Signs Guide

Construction Warning Signs are designed to highlight hazards and dangers that may be present on building sites and construction projects. Using recognised yellow and black warning symbols, these signs help workers and visitors identify risks before entering hazardous areas.

From moving plant and machinery to excavation works and overhead hazards, warning signs form an important part of site safety communication and help support effective risk management throughout a project.

Where Are Construction Warning Signs Used?

Construction site entrances
Excavation and groundwork areas
Scaffolding and elevated work zones
Vehicle routes and loading areas
Plant and machinery operating zones
Temporary work sites
Demolition projects
Restricted access locations

Types Of Construction Warning Signs

Available Materials

Self-Adhesive Vinyl

Ideal for smooth indoor surfaces including cabins, doors and equipment.

Rigid Plastic

Durable and suitable for most construction site environments.

Aluminium Composite (3mm)

Provides long-lasting performance and excellent weather resistance outdoors.

Recyclable Correx ® (4mm)

Correx is lightweight and ideal for temporary signage. Can be recycled via many kerbside programs.

Related Core Safety Signs Categories

Safety Advice & Guides

Frequently Asked Questions

What are construction warning signs?

Construction warning signs identify hazards and potential dangers on building sites to help reduce risks and improve safety awareness.

What colour are construction warning signs?

Warning signs typically use a yellow background with black symbols and borders to indicate potential hazards.

Where should construction warning signs be installed?

They should be placed wherever hazards exist, including site entrances, excavation areas, machinery zones and restricted access locations.

What hazards do construction warning signs identify?

Common hazards include moving vehicles, excavations, overhead work, hazardous materials, electrical risks and uneven ground.

Are warning signs mandatory on construction sites?

Warning signs should be used wherever significant hazards cannot be eliminated and workers or visitors need to be alerted to risks.

Can construction warning signs be used outdoors?

Yes. Rigid plastic, aluminium and correx signs are suitable for outdoor construction site environments.

Can I order custom construction warning signs?

Yes. Rainbow Safety can manufacture bespoke warning signs featuring custom wording, symbols and site-specific hazards.

Are Rainbow Safety warning signs manufactured in the UK?

Yes. Rainbow Safety manufactures a wide range of construction warning signs in the UK for quality, consistency and fast delivery.

Why Buy From Rainbow Safety?

Manufactured in the UK
Over 30 years of construction safety signage expertise
Fast dispatch on standard products
Trade discounts available
Custom warning signs manufactured to order
Large range of construction and workplace safety signs
Trusted by UK contractors, developers and local authorities
Expert support from an experienced safety signage team