One industry – zero carbon

In January 2008, UK mastic asphalt became the first industry in the world to achieve the CarbonZero standard.

Our 100 independent contractors, hauliers, installers and manufacturers are now 100% committed to reducing climate change by cutting the carbon footprint of any building, anywhere.

This means anyone choosing advanced mastic asphalt systems to waterproof their project will get a totally CO₂ neutral solution – ideal for eco friendly developments.

The Mastic Asphalt Council’s Carbon 100 initiative also means thousands of associated sub-contractors will have to meet the strict CarbonZero standard.

Where has all the carbon gone

So, we hear you ask, how can an industry the size and scale of MAC – along with thousands of associated subcontractors – go completely CarbonZero?

With help from experts at co2balance, members first evaluated all their processes – from production to delivery and installation – cutting as many unnecessary carbon emissions as possible.

This left MAC with a 165kg surplus of carbon dioxide per tonne of mastic asphalt laid.

Through co2balance, council members are offsetting these harmful emissions by investing funds in energy efficient projects that absorb or prevent the exact tonnage of their Carbon Footprint.

These include:

• Providing energy efficient bulbs in Kenya
• Replacing kerosene lamps in East Africa with solar powered lanterns
• Supporting sustainable forestation projects in the UK

What are green roofs?

A green or ‘living’ roof is essentially the growing of plants on our rooftops.   The insulative properties of soil and plants have been utilised by humans for thousands of years, cooling buildings in Africa and helping to retain heat in traditional buildings of Northern Europe and Scandinavia.   Modern green roof systems combine a series of functioning layers which recreate growing conditions across the roof.   Green roofs can be anything from a thin growing layer of sedums and mosses to plants, shrubs and water features.   They are installed on top of conventional roofs.    Properly designed, they are stable, living ecosystems that replicate many of the processes found in nature.

What are the major advantages of green roofs?

Green roofs provide many ecological and aesthetic benefits, including:

• Controlling water runoff, erosion and pollution,
• Improving water quality,
• Mitigating urban heat-island effects, cooling and cleaning the air,
• More than doubling the service life of the roof,
• Conserving energy,
• Reducing sound reflection and transmission,
• Creating wildlife habitat, and
• Improving the aesthetic environment in both work and home settings.

What are the most important factors in designing a green roof?

•  Climate, especially temperature and rainfall patterns
•  Strength of the supporting structure
•  Size, slope, height, and direction of the roof
•  Type of underlying waterproofing
•  Drainage elements, such as drains, scuppers, and drainage conduits
•  Accessibility and intended use
•  Visibility, fit with architecture, and owner’s aesthetic preferences
•  Fit with other ‘green’ systems, such as solar panels
•  Costs of materials and labour
 
What is the difference between an ‘extensive’, ‘intensive’ green or ‘brown’ roof?

Extensive    lightweight, low cost and maintenance.   Normally less than 6 inches deep, and, depending on depth, may support a range of plants, such as Sedums (low-growing succulents), herbs, meadow grasses, and perennials.

Intensive deeper substrate on load bearing applications.   Multifunctional systems can sustain complex landscapes, including small trees and even small ornamental ponds and fountains.

Bio-diverse or Brown       are like substrate based roofs, but roughly translated they recreates the surrounding wildlife habitats, can use recycled materials and are generally left to colonise naturally or seeded with an animal wildflower mix.
 
How much does a green roof weigh?

Green roofs vary greatly in weight, depending on their depth and the materials used. The important measurement is ‘wet’ weight — fully-saturated fabrics and plants.   Weights are about 60-150kg square metre.   Any calculations must take into account the weight of water held in the soil and any snow loading.

How does a green roof affect the conventional roof below it?

One of most important benefits of green roofs is protection for the underlying waterproofing membrane and can be expected to double or triple the life of the underlying conventional roof by protecting from human activity and wind-blown debris; shielding from UV radiation; and buffering temperature extremes, thereby minimizing damage from daily expansion and contraction.

The ‘conventional’ approach to green roof design focuses on covering 100% of the waterproofing materials. In particular, conventional green roof detailing focuses on covering and protecting the most vulnerable parts of the roofing system: its flashings, penetrations, terminations and drains. One example is the use of enclosed drain access chambers to protect drains and scuppers and to eliminate the potential for clogging by blowing trash or vegetation.   Green roofs, provide 100% protection by incorporating vegetated or stone margins, drain access chambers, etc.
 
What kind of waterproofing do I need?

Many types of waterproofing are compatible with green roofs. Bituminous membranes, single ply and liquid coatings are the most common. Many of these installations have now been in place for over 30 years and continue to perform as designed. PVC, EPDM and thermal polyolefin (TPO) are, in most cases, inherently root-resistant; other common waterproofing materials require a root barrier between the waterproofing materials and the vegetated cover.

How do Green Roofs affect the building they are on?

Green Roofs reduce the temperature inside the building they are on during increasingly hot summer months.   The UK currently spend more money (uses more energy) cooling buildings than heating them in winter.   Green Roofs reduce the need for air conditioning in the summer and as a result reduce CO2 emissions and keep the building cool.
How do Green Roofs affect the quality of life for people?

Green Roofs contribute to a greener urban environment and quality of life for communities in high density areas.
How do Green Roofs affect wildlife?

New developments lead to a loss of habitats.  Green Roofs can contribute to biodiversity and address local biodiversity action plans.  In particular they have been to favour many rare invertebrates found on brown field sites, as well as ground nesting birds such as skylarks.

Are leaks under a conventional green roof a problem?

Leaks in the waterproofing layer are less likely when it is protected from the elements by a green roof.   If a leak does occur, it can readily be located through new electronic technology which can rapidly and accurately pinpoint even minute holes.   These systems are more reliable than the older testing method and can even be used on steeply-sloped surfaces. Repairs to the waterproofing are quick, and disturbance of the green roof is minimal.

Is attaching all elements of the green roof to the underlying structure important?

Plant roots bind the layers of media and fabrics to create a unified cover, and the plants themselves create enough surface wind turbulence to foil potential uplift.   If your green roof will be located in an unusually high wind area, such as a high rise building or coastal area you may need to use appropriate ballasts which should withstand winds of up to 94 mph using concealed ballasts.
 
How steeply pitched can the roof be?

The maximum slope recommended for conventional green roofs is 30 degrees, pitch. A variety of methods utilizing meshes, slope stabilization panels, cribbing, or battens can be used to secure the green roof and prevent media shifting and erosion. 
 
Roofs with pitches greater than 30 degrees can be greened; however, special techniques are required.    

Do I need to consult a Structural Engineer?

It is always advisable to contact a Structural Engineer, however if you have discussed the design with Building Control and they are satisfied that the nature of the work does not require additional strengthening it is your choice whether to ask structural engineer.

 
In what climates do green roofs work?

Green roofs have been built most widely in temperate climates, but special techniques allow them to thrive in semi-arid, tropical, and even windy coastal areas and have been installed from hot, moist to the cold, windy locations.
 
Is irrigation required? If so, what kind?

With thoughtful planning irrigation is rarely necessary.   When irrigation is required, the water should be delivered deep under the surface—where the roots will seek it and it will not be lost to evaporation. Surface irrigation systems are wasteful and require more maintenance than subsurface irrigation methods.

How do Green Roofs affect water drainage from the roof?

Research from around the world indicates that Green Roofs reduce annual run-off roofs by at least 50% and more usually by 60-70%, contributing to urban drainage and flood alleviation schemes.   Moreover, the rate of release following heavy rainfall is slowed, reducing the problems associated with storm surges.   With an increasing need for developments to have limited water run off the Environment Agency now highlights the use of Green Roofs in their May 2003 publication ‘Sustainable Drainage Systems’ and introduction.

What kinds of plants should be used on a green roof?

In areas where frost occurs at least half of the plants installed on an extensive green roof should be varieties of Sedum.   In colder climates grass-dominated covers are recommended.   Reliable tropical plant lists are not recommended.    
Many other plants can be incorporated to provide habitat value or visual interest.   Appropriate auxiliary plants will vary by region, but generally, the deeper the green roof, the more complex the plant community that can be sustained.   They range from Sedum and herbs on the thinnest systems, to meadow grasses and perennials on mid-weight roofs, to turf and small trees on the deep, ‘intensive’ roofs.   The selections will depend on many factors: depth of growing media, seasonal temperature ranges, average rainfall, and the aesthetic preferences of the owner.

Where do I buy seeds or plants to build my green roof?

We can either supply plants or seed or advise you where to buy them.

Are any green roof plants invasive non-natives that could be spread by wind?

The only Sedum that might be considered invasive is Sedum sarmentosum also known as Star Sedum, Gold Moss, Stringy Stonecrop, or Graveyard Moss.   It has green spearhead-shaped leaves, lemon yellow flowers, and long tendrils and is not recommended.

How are green roof plants started?

There are several methods for starting green roof plantings. From April through October, Sedums may be established from fresh cuttings. Broadcast on the growing media, these cuttings will quickly form roots and affix themselves. Alternatively, Sedums may be started in May-June or September-October from 72-cell plugs, planted a foot apart.   Perennials can be seeded, except during the summer months.   A bio-or photo-degradable wind barrier fabric or hydro mulch is required while the plants are being established.
 
How long until the roof will be fully covered?

Generally, a green roof that is planted correctly will reach maturity in two growing seasons, or less.   Occasionally, reduced sun or rain may slow the process.   If more rapid maturity is desired, pre-grown Sedum mats, can be used.
 
Is there a danger of dry plants catching and spreading fire?

Not if the green roof is designed correctly.    Green roofs actually have a better fire rating than conventional roofs because the mineral media layers cannot burn.   The extensive use of Sedums and gravel borders and breaks also protect against fire

What effect will the winter freeze and thaw cycles have on the roof?

Not all green roofs are resistant to freeze and thaw cycles.    

Is there erosion in the winter when the vegetation dies back?

The design of a green roof system should include a significant percentage of non-deciduous plants, so that the mature cover is never 0bare of foliage and the potential for erosion is minimized.   The risk for erosion is greatest just after the initial planting.  

Can I plant a flower or vegetable garden on my roof?

Generally, green roof systems are not deep enough for growing vegetables and the tools of traditional gardening would damage the green roof and the underlying waterproofing.   However, incorporating container gardens or modular elements can accommodate an owner’s horticultural or agricultural desires.
 
Will I be able to walk on my green roof? Can it be used for recreation?

If the roof is accessible from the building and the roof will support the weight, decks, patios, and walkway pavers can be integrated into the design of the green roof.   Among the available plant covers, only turf grass will stand up to regular foot traffic.  Turf green roofs will require a minimum of 6 – 9 inches of media depth and irrigation is mandatory (i.e., an intensive green roof). As an alternative, stepping stones or walkways can be used to provide access through more fragile extensive green roofs.
 
What kind of maintenance is required?

Generally, after the plants have become established, most extensive green roofs only need weeding and occasional infill transplanting.   Maintenance visits should be timed to intercept any weeds before they go to seed and should be sufficient to maintain the health of the plants and protect the underlying roofing materials.

Can green roofs be combined with other green features?

Green roofs can be designed in conjunction with solar panels and in combination with other ‘low-impact’ development measures, such as infiltration beds, rain gardens, bio-retention systems, cisterns and rain barrels.

Can recycled materials be used in constructing green roofs?

Reducing the use of virgin materials is an important goal if the green roof industry is to be sustainable in the long run.   

How much does a green roof cost?

Cost per square foot depends on many factors: the size and slope of the roof, depth and complexity of the system, height and accessibility from the ground, cost of labour, and need for specialised elements, such as drains, railings, pavers, slope stabilization measures, etc.    

What financial benefits do green roofs provide?

Years of experience throughout the world have shown that a green roof can be expected to outlast a comparable roof without a green roof by a factor of at least two, and often three, many experts expect that these installations will last 50 years and longer before they require significant repair or replacement.    For a building owner with a long-term investment in the roofing system, this benefit factor goes a long-way toward paying back the initial investment in a green roof.

Will a green roof save energy?

Yes, although not due to insulation or “r-factors.”   A green roof acts as a heat sink, slowly absorbing and holding energy from sunlight and releasing it when the ambient air cools.   In this way, it acts as a heat “storage battery” and reduces the heating and cooling demands within the building.    Energy savings will be greatest in low buildings, due to the high ratio of roof area to the total of exposed building skin.    

Does a Green Roof require planning permission?

It is always advisable to contact your local planning department and explain what you are aiming to do, especially if it is on a permanent structure such as an office, dwelling or garage.  They will advise you on what your next steps should be, they will also ask you to speak to Building Control who will be interested in the technical nature of the installation i.e. building loading etc.

 
IS THERE ANYTHING I SHOULD AVOID IN BUILDING A GREEN ROOF?
 
To build and maintain a successful green roof, there are several design and installation problems to avoid:
 
Avoid any design that is not properly drained.

Inadequate drainage can result in:
      (1) Dead weight that the roof may not be able to sustain;
      (2) Plant mortality; and
      (3) Degeneration of the planting media
Avoid using herbicides to prevent root penetration of the waterproofing.

Herbicides will eventually leach out of materials, escaping into the environment and diminishing the root-inhibiting function of the root-barrier. When supplemental root-barriers are required, we recommend using thermoplastic membrane.   

Avoid using surface irrigation, if at all possible.

Surface drip and spray systems are expensive to maintain, do not deliver water efficiently to the roots, where it is most needed — and waste enormous amounts of water through evaporation. Also, on surface-irrigated green roofs plant roots tend to develop nearer the surface. This makes the covers increasingly dependent on irrigation and vulnerable to lapses in the watering schedule.
 
Avoid providers who know only one tune.

No one system is suited to all roofs—there are too many variations in pitch, drainage, climate, and exposure, to name but a few engineering considerations. ‘One-size-fits-all’ serves the aims of the manufacturer, not the needs of the consumer.
 
Finally, avoid false economies.

Your green roof is a long-range investment. The highest return will come from thoughtful, responsive design engineering and stringent standards of installation and maintenance, giving you a trouble-free green roof for years to come. 
 

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BBA Certificates

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The Cancellation of Contracts made in a Consumer’s Home or Place of Work etc. Regulations 2008.   These regulations came into force on 1 October 2008. They apply only to domestic roofing work by way of repair, refurbishment or improvement which is ordered on an unsolicited visit.

This note is a general guide provided to members for guidance. Readers must take legal advice in relation to their individual situations.

1.         The regulations give a client the right to cancel work and materials ordered during a roofer’s unsolicited visit at the client’s home, at the client’s place of work or at another’s home.

The client must be given notice that he/she has the right to cancel during a cooling off period.

2.         Agreements made by word of mouth for work are just as binding as contracts made in writing or by email.

The regulations also apply to work agreed during a visit requested by the client following the roofer’s unsolicited phone call or following an earlier unsolicited visit.

The regulations apply to work agreed during a visit to the client requested by the client after an unsolicited telephone recommendation made on behalf of the roofer.

The regulations do not apply to work for business clients or to new building.

The regulations apply to repair refurbishment or improvement of a property and to extensions, patios, conservatories or driveways.

The regulations do not apply to emergency work.

The regulations do not apply to agreements concluded after a visit to the client’s home. An example would be when a written quotation is posted by the roofer and the client’s acceptance is signed and posted by the client to the roofer.

DO’S and DO NOT’S

DO’S

Preferably post or leave a written quotation after a visit to the client’s home. The client then reads, signs for acceptance and posts the quotation back.

If the client signs and hands over a signed quotation at his/her home, hand to the client the written notice of cancellation rights.

If the client wants work to start before the cooling off period ends, get a written request from the client to start work.

Reimburse any deposit or advance payment paid if the client cancels during the cancellation period.

Preferably post or leave a written quotation after a visit to the client’s home. The client then reads, signs for acceptance and posts the quotation back.

If the client signs and hands over a signed quotation at his/her home, hand to the client the written notice of cancellation rights.

If the client wants work to start before the cooling off period ends, get a written request from the client to start work.

Reimburse any deposit or advance payment paid if the client cancels during the cancellation period

Do Not’s

Do not ignore these regulations; they will be enforced against “cowboys”. There are penalties against companies and individuals in the event of breaches.

Do not refuse emergency work. Emergency work is not affected.

Never begin work before the end of the seven day cooling off period without a written request by the client to do so. The client can always cancel during the cooling off period, even if he/she has asked for the work to start and the work has started.

The Cancellation of Contracts made in a Consumer’s Home or Place of Work etc. Regulations 2008.   These regulations came into force on 1 October 2008. They apply only to domestic roofing work by way of repair, refurbishment or improvement which is ordered on an unsolicited visit.

This note is a general guide provided to members for guidance. Readers must take legal advice in relation to their individual situations.

1.         The regulations give a client the right to cancel work and materials ordered during a roofer’s unsolicited visit at the client’s home, at the client’s place of work or at another’s home.

The client must be given notice that he/she has the right to cancel during a cooling off period.

2.         Agreements made by word of mouth for work are just as binding as contracts made in writing or by email.

The regulations also apply to work agreed during a visit requested by the client following the roofer’s unsolicited phone call or following an earlier unsolicited visit.

The regulations apply to work agreed during a visit to the client requested by the client after an unsolicited telephone recommendation made on behalf of the roofer.

The regulations do not apply to work for business clients or to new building.

The regulations apply to repair refurbishment or improvement of a property and to extensions, patios, conservatories or driveways.

The regulations do not apply to emergency work.

The regulations do not apply to agreements concluded after a visit to the client’s home. An example would be when a written quotation is posted by the roofer and the client’s acceptance is signed and posted by the client to the roofer.

DO’S and DO NOT’S

DO’S

Preferably post or leave a written quotation after a visit to the client’s home. The client then reads, signs for acceptance and posts the quotation back.

If the client signs and hands over a signed quotation at his/her home, hand to the client the written notice of cancellation rights.

If the client wants work to start before the cooling off period ends, get a written request from the client to start work.

Reimburse any deposit or advance payment paid if the client cancels during the cancellation period.

Preferably post or leave a written quotation after a visit to the client’s home. The client then reads, signs for acceptance and posts the quotation back.

If the client signs and hands over a signed quotation at his/her home, hand to the client the written notice of cancellation rights.

If the client wants work to start before the cooling off period ends, get a written request from the client to start work.

Reimburse any deposit or advance payment paid if the client cancels during the cancellation period

Do Not’s

Do not ignore these regulations; they will be enforced against “cowboys”. There are penalties against companies and individuals in the event of breaches.

Do not refuse emergency work. Emergency work is not affected.

Never begin work before the end of the seven day cooling off period without a written request by the client to do so. The client can always cancel during the cooling off period, even if he/she has asked for the work to start and the work has started.

It provides a substrate of good laminar and compressive strength suitable for asphalt roofing and with its low coefficient of thermal expansion will accept a full bonded built-up roofing specification. Although cork is somewhat friable during handling it is firm under foot traffic and is a suitable insulation to use below membranes which are subject to continual foot traffic, but an underlay may be required to provide support over the troughs of metal decking.   For general handling strength, a minimum 25mm thickness is recommended.

Why choose tapered (cut to falls) roof insulation? 

A Flat roof should never be truly flat!   The objective of tapered roof insulation systems is to reduce or eliminate the amount of standing water on the membrane where the roof deck does not provide adequate slope.   Ponding water can have an adverse effect on the waterproofing membrane and add excess weight to the structural deck, make routine maintenance more difficult and possibly more dangerous.   A correctly designed tapered roof insulation system not only provides the positive drainage needed, but also helps extend the life of the roof membrane.   The provision of a fall within a warm deck flat roof is normally achieved in one of three ways; tapered insulation, utilising timber firings under a plywood base or by laying a screed to falls.  

Independent studies have assessed both the cost and speed of each type of installation and found that tapered insulation proves to be:

Less costly to install

Quicker to install – estimated drying times for sand and cement screed to falls systems are in the region of 100 days plus after which the insulation and waterproofing need to be installed.  

Estimated installation times for a tapered insulation systems and the waterproofing membrane are between 50 – 150m² per day (dependant upon deck type and fixing method).

Reduced Weight – standard sand: cement screed weighs approximately 2000kg/m³.   Tapered insulation systems varying dependant upon insulant type; e.g. Rigid PIR – 32kg/m³, Rock Mineral Fibre – up to 180kg/m³.   Tapered insulation therefore offers a huge benefit in the reduced additional weight added to the structure.

Is more suitable for complex fall configurations – timber Firings can be complex to install when cross falls are required with the potential of condensation risk within voids formed by the firrings.   Additionally with tapered insulation the required fall can be achieved and the necessary thermal insulation is provided in ‘one-go’.