• Screen Covers

• Requirements

Two layers of protective screen shall be placed over the scaffolds to completely enclose the building structure for retaining dust and small debris. Tarpaulin and heavy duty nets shall be used to cover the exterior face of the scaffold. Tarpaulin shall be placed over the net. The screen system shall satisfy the requirements under the Air Pollution Control (Construction Dust) Regulation administered by the Environmental Protection Department, where applicable.

• Ties

The protective screens shall be secured to the scaffoldings at not more than 2 m intervals at both horizontal and vertical directions or the width of the net, whichever is less. The screens shall have a minimum overlapping width of 300 mm.

• Nets

• Materials and Installation

Heavy duty nets shall be relatively light weight and have good retaining capability for small debris. The material shall resist ultra-violet light deterioration. The nets shall be secured to the scaffold and at the catchfan so that debris can be retained and not deflected onto the ground.

The net shall meet the minimum requirements as listed in Table 3.3 or approved equivalent.

Table 3.3 Minimum Specification for Polyethylene Net

Criteria	Minimum Requirement
material	polyethylene
string diameter	1 mm
plys	16
mesh grid opening	20 mm
weight	130 g/m2

• Tarpaulin

Tarpaulin shall be light weight and constructed of fire retardant materials.

The fire retardant characteristic of the tarpaulin shall meet either one of the following requirements:

• Class B material as specified in British Standard 5867;
  • Flame retardant test for certain items, light weight cloths methods, provided by the Fire Retardant Regulations for Protective Canvas for Construction, Japan Ministerial Ordinance of the Ministry of Home Affair; or
    • Any equivalent standard criteria or testing.