Construction site organisation is a critical phase in architectural project management, influencing safety, efficiency, and overall project success. In Kenya, where urban construction sites often face space constraints and complex regulatory requirements, meticulous site planning ensures smooth workflow and compliance with local standards. This chapter explores the essential elements of organising a construction site, focusing on site hoarding and the designation of site activities. Understanding these aspects equips architecture professionals to manage site logistics effectively, reducing delays and enhancing collaboration among stakeholders.

1.1 Site hoarding erection

Site hoarding is a fundamental element in managing construction sites, serving multiple purposes including security, safety, and public communication. In Kenya, erecting appropriate hoarding is often mandated by county government regulations to protect both the site and the public. Proper hoarding also helps delineate the construction boundary clearly, preventing unauthorized access and minimizing hazards to passersby and neighbouring properties.

1.1.1 Types of hoarding

Site hoarding comes in various forms, each suited for different site conditions and project requirements. The choice of hoarding type impacts not only security but also project image and community relations.

1.1.1.1 Timber hoarding

Timber hoarding is widely used in Nairobi and other urban centres due to its availability and ease of installation. It involves erecting wooden panels, usually plywood or boards, supported by timber or steel posts set in the ground and braced on the site side. Timber hoarding provides a solid physical barrier that can be painted with project information, but it requires maintenance to prevent deterioration from weather. It is normally about 2.4 m high, with lockable gates for vehicles and workers. Example: a contractor building a four-storey SACCO office block in Nyeri enclosed the site with painted plywood hoarding displaying the project signboard and safety notices.

Steps for erecting timber hoarding

1. Set out the line: Mark the hoarding line on the site boundary with pegs and a string line, including gate positions.
2. Dig post holes: Excavate holes about 600 mm deep at the planned post spacing.
3. Erect the posts: Stand the treated posts in the holes, plumb them and fix them with concrete or rammed soil.
4. Fix the rails: Nail or screw horizontal rails to the posts at the bottom, middle and top.
5. Fix the panels: Nail the plywood sheets to the rails, keeping joints tight and the top line level.
6. Brace the hoarding: Fix raking struts on the site side to resist wind loads.
7. Hang the gates: Install lockable vehicle and pedestrian gates with strong hinges.
8. Paint and sign: Paint the hoarding and fix the project signboard and safety signs.

Worked example: posts and plywood sheets

Number of posts = perimeter ÷ post spacing (closed loop)

A site measures 40 m × 30 m, and posts are spaced at 2.4 m.

Perimeter = 2 × (40 + 30) = 140 m

Number of posts = 140 ÷ 2.4

Number of posts = 58.3, rounded up to 59 posts

Number of sheets = perimeter ÷ sheet width (sheets fixed upright)

Number of sheets = 140 ÷ 1.22

Number of sheets = 114.8, rounded up to 115 sheets

1.1.1.2 Steel hoarding

Steel hoarding, often made from corrugated iron sheets or profiled steel panels fixed to steel posts and rails, offers enhanced durability and security compared to timber. It is favoured for large commercial projects such as shopping malls or office complexes, for example, in Nairobi’s Westlands area, where vandalism risks are higher. Steel hoarding is fire-resistant and can be reused across projects, though it is heavier and requires more robust support. Modular steel hoarding systems with bolted panels can be erected and dismantled quickly. Example: a contractor extending a referral hospital erected galvanised steel panel hoarding around the works so the busy hospital compound stayed safe and the panels could be reused on the next project.

Steps for erecting steel hoarding

1. Set out the line: Mark the hoarding line and gate positions with pegs and string.
2. Excavate post holes: Dig holes about 600 mm deep at the planned post spacing.
3. Set the posts: Stand the steel posts, plumb and align them, and concrete the bases.
4. Fix the rails: Weld or bolt the horizontal rails to the posts once the concrete has set.
5. Fix the sheets: Screw or bolt the sheets to the rails, overlapping by one corrugation.
6. Install gates: Hang steel gates with heavy-duty hinges, locks and stops.
7. Protect against corrosion: Paint welds and cut edges with anti-rust primer and finishing paint.
8. Add signage: Fix project boards, safety signs and lighting where required.

Worked example: corrugated sheets and cost

Number of sheets = perimeter ÷ effective cover width

The same 140 m perimeter is clad with sheets giving 0.8 m effective cover each.

Number of sheets = 140 ÷ 0.8

Number of sheets = 175 sheets

Cost of sheets = number of sheets × price per sheet

Each sheet costs Ksh 1,100.

Cost = 175 × 1,100

Cost = Ksh 192,500

1.1.1.3 Mesh hoarding

Mesh hoarding consists of welded wire mesh or chain link fencing, typically used where visibility into the site is necessary for monitoring or aesthetic reasons. It is common in public infrastructure projects like county government offices where transparency and surveillance are priorities. Mesh hoarding is less secure than solid panels and usually supplemented with security patrols. Temporary mesh panels standing in heavy concrete or plastic feet and clamped together can be erected very quickly without digging. Example: a contractor adding classrooms to an occupied primary school used clamped mesh panels with shade netting to keep pupils away from the works while teachers could still see in.

Steps for erecting mesh hoarding

1. Set out the line: Mark the fence line, gates and pedestrian walkways.
2. Place the feet: Lay panel feet at the panel spacing along the line.
3. Stand the panels: Insert panel legs into the feet and stand them upright.
4. Clamp the panels: Join adjacent panels with couplers at top and bottom.
5. Fit stabilisers: Add bracing struts and weights at regular intervals and at corners.
6. Attach netting and signs: Fix shade netting and warning signs to the mesh.
7. Install gates: Fit gate panels with locks for site access.
8. Inspect regularly: Check daily for displaced panels, loose clamps and gaps.

Worked example: number of mesh panels

Number of panels = perimeter ÷ panel width (closed loop)

The 140 m perimeter is enclosed with panels 3.5 m wide.

Number of panels = 140 ÷ 3.5

Number of panels = 40 panels, with 40 feet

Composite hoarding

Composite hoarding combines materials such as timber frames with metal or mesh panels to balance security, cost, and aesthetics. It can be customised with safety signage and project branding, enhancing public perception. For example, a private university expansion project in Kisumu employed composite hoarding to maintain a professional site appearance while ensuring safety.

Temporary hoarding

Temporary hoarding is designed for short-term projects or phases, using lightweight materials like plywood or plastic panels. It is quick to assemble and dismantle, suitable for small-scale residential developments or minor renovations in town centres. Despite being temporary, it must still comply with safety standards to protect workers and the public.

Chapter Summary

This chapter focused on the organisation of a construction site, beginning with the erection of site hoarding, where timber, steel, and mesh hoardings were examined as common types used to secure and demarcate the site. The designation of site activities was discussed in detail, covering preconstruction tasks such as excavation, backfilling, site clearing, installations, landscaping, site surveys, permit acquisition, procurement, and resource mobilization. Further attention was given to site preparation, including clearing, grading, layout, levelling, and excavation for foundations and utilities. The process of foundation construction was explored, highlighting excavation, formwork, reinforcement placement, and concrete pouring and curing. Structural construction phases were outlined with emphasis on masonry work, roof construction, and steel erection. Finally, the installation of site utilities was addressed, emphasizing critical considerations such as safety, quality of workmanship, regulatory compliance, cost management, and the coordination of activities to ensure efficient and effective utility provision throughout the construction process.