Green Roofs and Walls...

[The Cell]

Welcome to the thread to promote green roofs [roofs that are intentionally vegetated] and provide advice for their installation.

In the US, the increased pressures on urban land and increased density levels are likely to have adverse impacts on drainage, water abstraction, biodiversity, accessible green space, and local climate conditions. A green roof system can play a positive role in mitigating these impacts and contributing towards an increase in quality of the urban environment.

Green roofs can provide a wide range of benefits to buildings, their owners and users, and the immediate environment. Green roofs date from the 1930s, but a conservative building and planning culture has traditionally served to constrain their installation.

However, over the past 5 years there has been a renewed interest in green roofs, and growing confluence of growers, suppliers, ecologists, architects, designers and others with an interest in green roofs to bring about change in order that green roofs can contribute fully to the living environment of our towns, cities and villages.

This thread has been established to assist in our green roof renaissance; to provide a comprehensive resource and forum for ours and other planners, developers, architects, and those wishing to design, install or promote green roofs. It aims to identify pit-falls and problems, as well as highlight the many benefits of green roofs and case studies of good practice.

Established in 2008, we are only at the start of this process, and the Cell Habitat will seek to develop these resources substantially over the forthcoming years. If you are interested in joining us in this work, or have green roof information and / or examples of specific projects, which you think others will find useful, please post, it is not necessary to join to post.

Note: Special thanks to the guys at Living Roofs for info and pix.
livingroofs.org/

and here is a link to the European Guidelines - Comparison Between The German (FLL), Austrian And Swiss Green Roof
livingroofs.org/NewFiles/COMPARISON-GUIDELINES1.pdf


the mgmt.

[The Cell]

Introduction

Green Roofs are, in short, vegetated roofs, or roofs with vegetated spaces. They are also referred to as eco-roofs and roof gardens. Green roofs have been with us for centuries ranging from the hanging gardens of Babylon to the turf roofed dwellings of Ireland and Scandinavia. However, modern green roofs have largely developed in the last 50 years, with increasing sophistication to meet a growing range of needs.

Most of this technological advance has been made in Germany; their growth in the 1970s and 1980s has lead to £39million industry. The modern green roof systems are highly durable and provide a number of key sustainable and environmental benefits. The German Green Roof Standards, known as the FLL, are very high and all systems are required to be tested for to ensure that they perform to the highest building standards, whether that be waterproofing or fire resistance. No such standards are in force within the UK, although the larger manufacturers accord to them.

Around the world, the growth of self-build and ecological construction processes from the late 1960s saw an increasing interest in green roofs over the following decades. However, this was never fully exploited by either the industry or policy-makers, and consequently the world remains without incentives, standards, or policies to encourage the installation of green roofs.


Myths still abound. There are concerns within the professions and public that green roofs are more liable to leak than traditional roofing systems. This is partly down to a preference for pitched, rather than flat roofs. However, vegetated roofs provide an extra protection to waterproofing systems from Ultra-Violet light, frost, erosion and other forms of weathering. If in the rare case that they do leak, this is largely down to poor roof construction, and not the green roof system itself.

Nevertheless, within the past 5 years we have witnessed a significant renewed interest in green roofs, and a marked increase in green roofs being designed and installed. Many of these are part of urban regeneration schemes, but be it the garden shed or a large commercial block in the heart of our cities, the opportunities are almost endless. We are, we believe, on the crest of a third wave of green roofs globally. Mechanisms are now being put in place to help ensure that this interest is sufficiently captured and developed in a way that the necessary policies, incentives and regulatory frameworks in put in place.

We aim to promote green roofs, green walls and other similar features, at all levels, working with industry, contractors, local authorities regeneration teams, researchers, and the wider public to ensure that they become a mainstream component of building design and function.


the mgmt.

[The Cell]

Intensive Green Roofs

Intensive green roofs have a deep growing medium, which allows the use of trees and shrubs. Some city parks are in fact intensive green roofs, such as the parks within the Canary Wharf Estate, Canada Square and West Ferry Circus and the roof of Cannon Street Station in London.


The depth of the growing medium requires extra loading requirements within the holding structure and requires a complex irrigation system for maintenance.

They are generally quite costly and require extra structural design to the building.



the mgmt

[The Cell]

Extensive Green Roofs

Extensive green roofs have a thin growing medium and require minimal maintenance, and in general due not require irrigation [some require irrigation initially]. They are generally less costly to install than intensive green roofs.

There are 3 types currently used:
1. Sedum mats

Sedum Mats - a sedum mat is a base layer of Polyester, Hessian, or porous polythene depending on the supplier, on which is laid the 2cm growing medium, on to which is sprinkled sedum cuttings. These grow into the substrate to maturity. When harvested the Sedum blanket is rolled up from the carrier upwards and delivered to site. When installed the Sedum blanket (including the 2cm of growing medium) is rolled out onto either 5 - 7cm of growing medium (standard method) or direct onto a moisture retention blanket (ultra light weight method).

Sedums are used because they are wind, frost and drought resistant not because they absorb water. Its ability to absorb water makes it drought resistant.

section through sedum mat green roof

2. Substrate based roof

7cm of crushed recycled brick is placed on the green roof system and plug planted with sedums or with sedum mats applied. There is a misconception that green roofs are made of turf. Although some green roofs are made of turf this is not generally the case.

Extensive hydro seeded extensive green roof cutaway

3. Green / Brown roofs for biodiversity

Similar to substrate based but can, in some cases, use recycled aggregate from site and generally left to colonise naturally or seeded with an annual wildflower mix or local seed source.

brown roof designed for biodiversity




the mgmt.

[The Cell]

Green Roofs in the Domestic Environment

The DIY Guide to Green & Living Roofs

This is a guidance note on Living Roofs in the garden, a leaflet published by Natural England in May 2006. It covers not just the why and the how but also what wildlife you can hope to attract to a living roof on a domestic or garden building.

This section provides more detailed information to accompany the leaflet. This is to help provide design guides and case studies of small scale green roofs.

English Nature became part of a new Government body called Natural England on 2 October 2006. The purpose of Natural England is to conserve and enhance the natural environment for its intrinsic value, the well-being and enjoyment of people and for the economic prosperity that it brings.

Livingroofs.org and Natural England are keen to publicise examples of green roofs in the garden. If you take the advice on this page and build a green roof we would really welcome pictures, examples of any innovative technique you may have used and any other information you think might be of interest to others. The number of domestic green roofs is still very small and your experience may be of real value to, and inspire, other people.

We are keen to publicise examples of green roofs in the garden. If you take the advice on this page and build a green roof we would really welcome pictures, examples of any innovative technique you may have used and any other information you think might be of interest to others. The number of domestic green roofs is still very small and your experience may be of real value to, and inspire, other people.

The information here is as comprehensive as we can make it. However, we do ask you to remember that we cannot possibly cover every situation and every contingency. What follows is therefore guidance rather than prescription. Most importantly, we strongly recommend that you get relevant professional advice regarding loadings and waterproofing.

We hope that this leaflet will encourage home owners to consider retrofitting green roofs on their sheds and on any flat roof space on other buildings in house or garden. Although the focus here is on sheds and other outbuildings, the same principles apply to flat roofs on extensions, balconies etc.

BEFORE YOU START:-

The first questions to ask are:

Is the waterproofing in good condition?

Can the roof taken the given load?
Then consider local wildlife:

1. What are the local and regional habitats that could be recreated on the roof and what species might benefit?

2. What soils and aggregates would be most appropriate and easily available locally? For example, limestone chippings from DIY shops would be good for limestone grassland.

3. Which plant species would be most likely to flourish in the conditions?

4. Although sedum species are recommended, do include appropriate flower-rich seed mixes or plug plants [www.wildflowers.co.uk is a good source].

5. AVOID seeding grasses! They will make their own way anyway, along with rosebay willowherb and other such aerial colonisers.

6. Add some moss from walls or normal roofs.

7. Include other elements such as dead wood, larger stones and nesting boxes to encourage invertebrates.

8. What butterfly food plants could be planted?

9. Be creative! Don’t worry if some of the plants don’t take or seem not to like the circumstances. Try others and add them instead.

PRINCIPLES:-

The essential components of a green roof are:

TIMBER FRAME – to hold the green roof elements onto the roof. In some cases, extra timber supports may be needed to ensure that the building can take the load.

ROOT MEMBRANE – this could be a pond liner or 300micron damp-proof membrane.

FILTER SHEET – this stops fine material from leaving the roof. It is generally a sheet like the type placed under patios to keep weeds out. It holds the fine soils but allows water to pass through. It can be bought at DIY stores.

MOISTURE BLANKET – essentially a woolly fleece that holds water. These can be bought commercial and are referred to as geotextile membranes. Cheap alternatives are cardboard or even old blankets/towels will do.

SUBSTRATE – this is the medium in which the plants will grow and should consist of aggregate such as crushed concrete/brick, limestone chippings, gravels or clay pellets. This should be at the base to free drainage. Above it, you need another layer, consisting of sand or soil [preferably subsoil] or both.

PLANTS – the species selected will depend on the substrate and the substrate depth. They could be seeded or plug planted.

A Manifesto For Gardens, People And Nature

This manifesto was launched by the Minister for Biodiversity, Joan Ruddock MP, on 18th July 2007, at Roots and Shoots in the London Borough of Lambeth.

The manifesto has several aims. It will:

* draw public attention to the importance of gardens for wildlife, for people and for the urban environment generally and to the threats that gardens currently face, from paving and development especially
* set out an agreed agenda for future action
* act as a rallying flag under which many different and disparate organisations can gather

The full text of the manifesto is at

www.naturalengland.org.uk/campaigns/breathingplaces/Docs/garden-manifesto.pdf


* Purpose, objectives and Terms of Reference of the Forum for Gardening with Wildlife in Mind
Purpose

“To inspire people to manage gardens for their own enjoyment in ways which also benefit wildlife”
Objectives

1. To cultivate a responsible attitude to the natural environment on the part of gardeners and the garden industry
2. To gather evidence supporting the benefits, to people and biodiversity, of gardening with wildlife in mind
3. By relaying this evidence, to assist people to make well-informed choices about their gardening activities
4. To help link people and nature, through their gardens, thereby encouraging a wider and deeper appreciation of biodiversity and sustainability



SHED DESIGN

This diagram shows the basic principles for two types of garden shed

Diagram of green roof installation on a garden shed

Photograph of garden shed with green roof fitted

Please note that the pitch shed will need a timber grid to hold material in



OUTHOUSE BRIGHTON

A simple green roof on an outside toilet in Brighton

Diagram of green roof fitted to an outhouse

Photograph of green roof installed on domestic outhouse

The growing medium was chalk and sub soil and the idea was
to create chalk grassland habitat for the Brighton and Hove Biodiversity Action Plan.
Seed mix was a calcareous flower mix.


BICYCLE SHED, PETERBOROUGH

Eventually seeded with Sedum acre (Biting stonecrop) and Thymus serpyllum (Breckland or creeping thyme)

The bike shed in its unadorned state

A frame was constructed on top of the bicycle store.
It was not attached to the roof but merely placed on it

A root membrane was made using plastic compost sacks split open and laid
across the roof in between the timber borders

root membrane made of empty compost bags opened out
A moisture blanket made of six old bathroom towels laid between the timbers

Six battens were screwed between the timber up stands
to hold the root green roof frame & brackets, and moisture layers in place to support the substrate, moisture layer for green roof
made from towels cross battens to support substrate



Expanded clay granules were placed in the compartments to a depth of 4 cm,
clay granules / pellets used as substrate




with 3cm of soil [this was a blend of a 35kg top soil
and 25kg sand in bags
bought from local garden center.

soil and sand mix as top substrate layer

the mgmt.

[The Cell]

Green Walls

Green walls are essentially a living, and therefore self-regenerating, cladding system using climbing plants. Whilst climbers have been used traditionally on buildings for centuries, modern methods using high-tensile steel cables have enabled the concept to be used far more adventurously. Contemporary architecture is also more suitable in many ways for facade greening than traditional buildings. With suitable species selection, heights of up to 25m can be attained – additionally if plants can be grown in large irrigated containers at height, then even greater heights can be reached.

The most commonly used species for wall-greening are ivy (Hedera sp.), Russian-vine (Fallopia sp.) and Virginia-creeper (Parthenocissus sp.). Both will climb directly onto wall faces, especially those of brick and stone where the porous surface allows them to attach more easily but the installation of trellises and wires can aid their growth, and to some extent serve to liit the direct contact between wall and plant. All can relatively quickly form a dense evergreen foliage many metres in height, and on many older buildings this is actively managed to ensure that it does not obscure windows and other openings. Such dense foliage provides an effective nesting habitat for a variety of birds, including robin, wren and blackbird, as well as serving to baffle noise. A number of varieties have colourful foliage, that will change with the seasons, often turning red or golden during autumn.

Other climbers, such as clematis (Clematis sp.), honeysuckle (Lonicera sp.), wisteria (Wisteria sp.), passion-flower (Passiflora sp.), bougainvillea (Bougainvillea sp.) morning-glory (Ipomoea sp.) and jasmine (Jasminum sp.) can be highly decorative, although will be usually slower-growing and not as bulky. Many will have highly colourful flowers that can serve as nectar sources for insects, as well as providing a pleasant scent.

Although it is often thought that these climbing plants can damage wall surfaces through their tendrils and feathered adventitious rootlets (in the case of ivy), in most cases if the wall is solid and well-built there is no reason why damage should occur. Care should be taken, however, in respect of walls with cavities or with crumbling mortar in which roots could take hold and expand.

Large-scale use of green walls is still a very new concept, however there is a solid research base, which has developed in Germany over the last 20 years. Active research is a major concern for several German academic institutions.

Visual Advantages

Public perception of contemporary architecture is often poor, with it being seen as barren and sterile. However, just as street trees do much to improve public perception of urban environments, so climbing plants can do the same for buildings. Large climbers, up to 25m high, can be extremely dramatic visually, as well as softening what may be seen as hard surfaces.

Climbing plants have traditionally been seen as ‘add-ons’ to buildings. The new approach, being pioneered in Switzerland and Germany, is to see them as integral to the design concept. Clearly this makes sense in both visual terms and in designing in practical features.

In addition to being used on buildings, climbers can be used on freestanding structures such as giant ‘pergolas’ or on poles. see MFO park illustration.

Advantages for Environment and Sustainability

Private benefits

Climbers can dramatically reduce the maximum temperatures of a building by shading walls from the sun, the daily temperature fluctuation being reduced by as much as 50%. The effectiveness of this cooling effect is related primarily to the total area shaded rather than the thickness of the climber (Köhler 1993). Together with the insulation effect, temperature fluctuations at the wall surface can be reduced from between –10º/14ºF to 60ºC/140ºF to between 5ºC/41ºF and 30º/86ºF (Peck et al 1999). The use of climbers to reduce solar heating is most effective if they are used on the wall that faces the sun, together with the west wall, which experiences afternoon heating.

Evergreen climbers provide winter insulation, by not only by maintaining a pillow of air between the plant and the wall, but by reducing wind chill on the wall surface. Reducing wind chill by 75% can reduce heating demand by 25% (Peck et al 1999). Reduction of wind chill is also reduced to some extent by the interwoven stems of deciduous climbers during winter. The effectiveness of winter insulation is related to the thickness of growth, which is generally related to the age of the plant. In some cases however growth patterns change as the plant ages, e.g. there may be a reduction in the dense twiggy growth that forms the most effective insulation.

Climbers on buildings can help protect the surface of the building from damage from very heavy rainfall and hail, and possibly can play some role in intercepting and temporarily holding water during rainstorms, in the way that green roofs do. They also help to shield the surface from ultra-violet light, which might be an important consideration for certain modern cladding materials.
Public benefits

Climbers have been shown to be highly effective at trapping dust and at concentrating certain dust-derived pollutants in their tissues, particularly in those tissues that are then discarded. In a study of climbers lead and cadmium concentrations were shown to be highest in dead leaves and dead wood. These heavy metals are thus taken out of the atmosphere and rain and concentrated in a form that then falls to the ground (Köhler 1993). The removal of dead leaves and branches and their disposal in sites where the concentrated heavy metals can do minimal environmental damage is thus a key factor in reducing the dangers presented by these elements.

There is strong anecdotal evidence that climbers on buildings help to reduce noise levels.

Reduction of solar heating of the sides of buildings helps to reduce the ‘heat island effect’, i.e. the effect whereby urban areas accentuate high temperatures in summer.

All green plants absorb CO2 emissions, thus climbers in urban areas help to reduce the contribution made to human-induced global warming.

All plants also absorb and breakdown a variety of pollutants, notably volatile organic compounds, and unburnt hydrocarbons from vehicle exhaust. It is a reasonable assumption that urban climbers could play a role in reducing these in city areas.

The use of climbing plants offers a very elegant solution to the problem of how to contribute to the local and regional biodiversity targets. Because they take up little horizontal space, but make use of vertical space that would otherwise be lifeless, they can add considerably to the area, which is potential habitat without taking up room on the ground.

The green walls also provide an opportunity for wildlife. Any climbing plant will offer habitat to invertebrates, such as insects and spiders, which in turn will be food for insect-eating birds and bats. Any climber will also act as a transit route for wildlife between habitat at ground level and those established on roofs in the form of green roofs.


the mgmt.

[The Cell]

(1) Introduction:

How does one set about planning, specifying, installing and maintaining a green roof, which is going to flourish rather than subsist?

To date there are no British Standards to guide Specifiers, Contractors, and their clients as to the best method to achieve this.

At present the most widely accepted standard amongst the leading green roof suppliers in the UK, is the German FLL standards (Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau). Translated – The landscaping and landscape Development Research Society. This charitable foundation has set out guidelines, which cover:

Distinguishing between types of landscape – Intensive; Semi Intensive; & Extensive and the factors which are going to affect the flourishing of each type of landscape i.e. site conditions for the vegetation; weather dependant factors; structure dependant factors; and plant dependant factors etc.

Root barriers – types and tests etc

Drainage layers – flow rates, water storage capacity etc

Growing Mediums – their porosity, weight, structure, water permeability, Carbonate and salt content. Nutrient capacity & pH value.

Plant and vegetation requirements

Planting, cultivation & maintenance – dry seeding, wet seeding, hydro seeding, Sedum mats & Turf laying; Readiness for handover, post installation maintenance

Wind Loads – preventing wind erosion

Independent testing of products to ensure standards are maintained

Experience shows that if a green roof is specified, installed and maintained to the FLL guidelines the landscape will flourish. If the system becomes a "mix & match" for economic reasons en route from the specification – tender – installation stage in it will almost certainly not flourish, and will be a disappointment.

(2) Specifying a Green Roof:

Before seeking advice on specifying a green roof it pays to arm oneself with some basic knowledge on the subject:

(a) Planning a green roof:

There a number of fundamental principles which apply to any type of green roof system and its successful installation whatever the proposed landscape and its locality or climate.

Waterproofing:

The waterproofing system beneath any green roof MUST be root resistant in the long term preferably to the German FLL standards. If the waterproofing is not root resistant then the green roof system must include a root barrier. The installation of the waterproofing and its detailing to perimeters, outlets, protrusions through the roof etc., MUST take into account the depth of the green roof build up. The waterproofing should always be 150mm above soil level at internal upstands and protrusions, and at least 50mm at external perimeters. The waterproofing system must be leak tested and certified as such IMMEDIATELY before the installation of the green roof.

Green Roof System:

No matter what species of plants are specified, for them to flourish the green roof system MUST provide them with:

* Moisture

* Drainage

* Aeration to the plants root systems

* Nutrients

To achieve this, a successful system must basically replicate nature but within a very compressed build up. The build up should always consist of:

* Moisture retention/protection layer

* Drainage layer

* Filter layer

* Manufactured/Recyled Growing medium

* Appropriate components i.e. outlet inspection chambers etc. The type, size, and design of each layer will depend on the proposed vegetation; as will the need or otherwise for irrigation.

Loading Weight:

It is fundamental that the saturated weight of the proposed green roof system is obtained and the information given to the client’s representative for issuing to the structural engineer. A reputable manufacturer/supplier of green roof systems will be able to supply product data sheets on each of the components comprising any particular green roof build up.

Installation:

Contractors who have been fully trained in their installation should only install green roof systems. It is COMPLETELY different to the installation of landscapes over natural ground.

Maintenance:

Client’s representatives are strongly advised to include the cost of post installation maintenance within the tender documents for an agreed period of time. This would ensure that the green roof is handed over in a healthy condition.

Warranties/Guarantees:

Warranties/guarantees, which are insurance backed and cover the products, the contractors workmanship, and consequential loss due to the defects of either, provides reassurance to the client. Additionally any design liability offered by the manufacturer/supplier of the green roof system underlines that providers commitment to the suitability of the system installed.

Before seeking advice:-

1. Decide exactly what landscape you & your client want – is it a low maintenance Extensive landscape? Intensive for recreational use? Ecological landscape to encourage wild life? Or some other?

2. What maintenance cost is the client prepared to pay for? Remember low maintenance does NOT mean NO maintenance! Even an Ecological landscape will require a twice-yearly inspection.

3. Be able to provide answers to structural questions from the Green Roof manufacturer/supplier such as, height, size and exposure of the roof, which direction is the roof facing, any loading restrictions, and in the case of large roofs, construction programme constraints, site access etc.

4. Have some idea, however vague, of the client’s budget for the roofing package.

5. Is the client prepared to get the main contractor to offset any cost savings from the "drainage package" against the costs of the "Roof & Green roof package" due to the significant reduction in water run off from the green roof?

6. Does the client REALLY want a guarantee/warranty, which is insurance backed? And does he want it to cover the WHOLE package of waterproofing, insulation, and green roof system? And from a single source? Or will he back down under “value engineering” alternatives that inevitably come from the main contractor?

These points seem obvious but it is amazing how often they are glossed over – often resulting in tenders coming in over budget with the resultant "value engineering exercise" which can compromise the quality of the green roof products and their installation.

Choosing a Manufacturer / Supplier:

Ideally a manufacturer/supplier should be able offer the clients representative ALL of the following:

* The complete system build up of Waterproofing; insulation; green roof system including the growing medium and in the case of Extensive roofs the plants. – This will enable them to credibly offer a single source warranty/guarantee.

* The green roof components including the growing medium should conform to at least the FLL standards

* Provide detailed specifications including detail drawings if required

* Provide an accurate budget price to the clients quantity surveyor for the cost of supplying & installing the complete system

* Provide loading weights of all components within the proposed system to the clients structural engineers.

* Product data on their components and their performance, such as flow rates on drainage layers etc.

* Provide growing medium that conforms to the FLL standards suitable to support the plants specified.

* Provide advice on plant options.

* Provide a list of approved contractors trained to install the system specified.

* On site assistance by trained members of staff to ensure standards of workmanship are maintained.

* A single source warranty/guarantee, insurance backed to cover the products, workmanship and consequential loss. Ideally backed by design liability.

* Provide evidence of a successful track record within the UK of projects completed, which can be inspected by the prospective clients representative.

(3) Post Installation Maintenance:

Every type of Green Roof system will require maintenance in some form or another, (a) initially for a period following the installation of the plants, and (b) ongoing maintenance to keep the green roof flourishing.

The specifier should seriously consider including in the tender documents the following paragraph or similar:

"Provision must be made by the contractor to include in his tender price, the cost of post installation maintenance for a period of two years, in order that a healthy green roof is handed over to the client"

Following hand over, the client is strongly advised to make arrangements for continuing the maintenance regime.

A suggested post installation regime could be:

(a) Extensive Green Roof – This should consist of a minimum of two visits per year by the appropriate labour force, which will be dictated by the roof area. No irrigation will be required once the plant layer is established. Procedures carried out in the first twelve months could include the following:-

(1) Removal of unwanted plant material

(2) Correction of any localised plant system problems

(3) Replacement of any failed plants exceeding 5% of total plants installed

(4) Application of nutrients

(5) Removal of dead flower heads (if required)

(6) Checks on outlets and drainage

(7) Replenishment of any areas of settled substrate.

Points (2), (3) and (7) are generally confined to year one. Subsequent years will see maintenance requirements reduce as the plant system establishes. At the end of year two we would recommend that the client consider negotiating a continuing programme of maintenance with the contractor on the basis that they will be familiar with what is required to maintain a healthy plant regime.

(b) Intensive Green Roof – The visits required to carry out maintenance will be dictated by the species of vegetation planted, and their irrigation and nutrient requirements. Procedures carried out in the first twelve months could include the following:-

(1) Removal of unwanted plant material

(2) Correction of any localised plant system problems

(3) Replacement of any failed plants exceeding 5% of total plants installed

(4) Application of nutrients

(5) Pruning, mowing & removal of dead vegetation

(6) Apply required irrigation in accordance with each plants requirements

(7) Replenishment of any areas of settled substrate.

Points (2), (3), and (7) are generally confined to year one. Ongoing maintenance will be dictated by the requirements of the species of vegetation planted. At the end of the post installation period we would recommend that the clients considers negotiating a continuing programme of maintenance with the contractor on the basis that they will be familiar with what is required to maintain a healthy plant regime.

Finally having taken the plunge and specified a Green Roof after taking everything into consideration there is one rule that should be remembered by all concerned and is especially relevant to the client getting a flourishing green roof!



the mgmt.