Built/Maintained by ArchSD

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Briefing for Green Roof in Schools Built/Maintained by ArchSD

17 June 2016

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Program

Introduction

Landscape Design and Plant Selection for Green Roof in School Maintenance of Green Roof in School

Recent Preliminary Inspection to the Schools completed with Green

Roof before handover to SSB but currently not maintained by ArchSD

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Introduction

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Green Roof – ArchSD Role

Construct Green Roof on New School Buildings under Head 703

- 48 Schools completed since 2003

- 1 government school currently maintained by ArchSD;

Retrofit Green Roof on Existing Government School Buildings

- 28 Schools completed since 2003 - all under ArchSD maintenance;

Maintenance of the building structure for Government School Buildings

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Tree root punching through planter box – seek maintenance agent advise

Green Roof Maintenance – General Tips

General Maintenance issues - Structural aspect to be covered later

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Debris/ weeds blocking drain outlets - routine cleaning needed

Green Roof Maintenance – General Tips

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Green Roof Maintenance – General Tips

In case there are trees in doubtful health conditions – conditions to be monitored

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L andscape Design and Plant Selection for Green Roof in School

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Benefits of Green Roof

Environmental Ecological

Economical Aesthetic

Psychological Educational

Image Source: Greening, Landscape and Tree Management Section, DEVB http://www.greening.gov.hk

Landscape Design and Plant Selection for Green Roof in School

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Design Intention

Types of Green Roof

Typical Sections

Plant Species

Softscape Maintenance

Content

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Design Intention

Diamond Hill Crematorium

EXTENSIVE INTENSIVE

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Types of Green Roof

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Retrofit Projects on Existing

Structures

Source

DEVB Skyrise Greenery Application in School

http://www.greening.gov.hk/en/

green_technologies/skyrise_

application.html

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Typical Section

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Green Roofs on New Buildings

Source

DEVB Skyrise Greenery Application in School

http://www.greening.gov.hk/en/green_technologies /skyrise_application.html

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Typical Section

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Source: DSD Project

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Typical Section

Typical soil depth for extensive green roof:

- 150mm for ground cover/turf planting for new roof;

Typical soil depth for raised up planters on structures/roofs:

- 300mm for ground cover / grass - 600mm for ground shrubs

- 1200mm for tree planting

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Plant Species

Right Plant at the Right Place !!!

http://www.greening.gov.hk/en/green_technologies/skyrise_guide.html

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Example – Zephyranthes candida

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Softscape Maintenance

Plant

Conditions Drainage Irrigation

Pest &

Diseases Weeding Fertilizing

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Maintenance Requirements

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Plant Condition

Weeding

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Irrigation Point

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Edge Condition

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Drainage

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More Information: https://www.greening.gov.hk

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Maintenance of Green Roof in School

校舍綠化天台的保養

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General

Observation

•no observable maintenance deficiency related to the green roof projects

completed by ArchSD

•as long as the green roof is properly designed and

constructed, there should be no specific building

maintenance issue

compared with similar

structures without green

roof.

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Water Tightness

•Green roof should be properly attended to prevent any potential damage to the existing water proofing layer.

•No evidence that the greening facilities will

adversely affect the water-

tightness of roof structure

so far.

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Structure

•Before installation of green roof, conduct

structural assessment by Registered Structural Engineer

•Maintenance check for any structural defect where necessary, e.g.

cracks, spalling concrete,

water leakage, etc.

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Routine

Management Attendance &

Inspection

•Attendance to clear surface channels

•Check Subsoil drainage and any movement joints under greening facilities

•Regular watering &

fertilizing.

•Regular weeding , plant

cutting & monitoring plant

growth

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Recent Preliminary Inspection to the Schools completed with Green Roof before handover to SSB but currently not maintained by ArchSD

(Observations in respect of Structural Safety)

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• Government Schools : maintained by ArchSD

• Non – government Schools : maintained by school/EDB

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• Preliminary Inspection in early June 2016 to 48 new Schools built by ArchSD

• Loading of original greening – already taken account in building design

• During this inspection, subsequent alteration & addition of greening was found in some schools.

• Sign of immediate danger at the time of inspection was not found, however follow up action is required

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Addition of large area of greening :

Large additional planters -> Increase in loading

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Extensive addition of pot planters - -> Increase in loading

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Addition of large planters concentrated at

small area -> Increase in loading

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Change of use of the roof -> Change of loading

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Minor cracks found at some RC beams under green roof – require further inspection and

investigation to determine whether the cracks are structural cracks caused by overloading

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Leakage problems found at some schools -

may lead to deterioration of the structure in

the long term – remedial works asap

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Suggested Follow Up Action

 Schools not maintained by ArchSD is subject to Buildings Ordinance under which BD submission and statutory compliance checking is needed

 Seek professional advice from AP/RSE

 Proper maintenance and repairs to the green roof, including drainage system, and the

supporting structure roof

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