Wednesday, April 16, 2014

Designing a Florida Green Roof to Withstand Daily Desiccating Winds

Understanding wind impacts on a green roof is so very important.  The below video depicts wind impacts across a new green roof we are working on at Disney in Orlando.  The green roof will be subject to strong winds.

We've measured daily wind speeds of 15 to 20 miles per hour or 7-9 meters per second.  Add to the direct impact of wind a rooftop temperature of 120 F + (50 C) and the rooftop growing environment is more like a high powered convection oven.  Remember 1 mile per hour equates to approximately 0.447 meters per second, or 0.466 feet per second.  An average rooftop wind speed of 2 M/Sec is normal in many locations.
A new Disney Green Roof is being constructed on the above sloped roof
Green roof plant selection is always modeled upon several factors, including two design variables - light and wind.  I always say that wind can be the silent killer of green roof plants.  Wind possible has more impact on the plant’s ability to grow second only to light and possibly water.   Wind directly controls and limits the hydrocycle within a living ecosystem, through water dessication.

A 2 M/Sec wind for example can cause a C3 or C4 type green roof plant to transpire at up to three times or more the normal level the plant is accustomed to, pulling water very quickly out of the leaves.  If the vascular biomechanics of the plant cannot supply water fast enough to the leaves then the plant may wilt or expire, even if adequate irrigation water exists in the root zone.

The 7-9 M/sec wind we are dealing with on this project is much higher than the wind speeds a normal rooftop encounters and to compound the issue, there is only a very tiny parapet (couple of inches).

The best way to determine wind exposure across the green roof is to use a hand held anemometer and record wind characteristics on the roof.   

Although a hand-held anemometer or portable weather station are relatively inexpensive and invaluable to understanding the potential wind impacts to the green roof plants, they may not always be available.  An effectively simple tool to use in place of an anemometer is a $1 pinwheel.  Hold the pinwheel above the roof at regular intervals to obtain a strong visual interpretation of wind strength.  If, on the average, the pinwheel does not spin then you can classify the area as having a wind variable of 'low'.  If the pinwheel on average spins moderately fast then use the variable 'moderate'.  If the pinwheel spins wildly all the time then the corresponding roof area should be classified as 'high'.

Testing the pinwheel side by side with an anemometer will allow a better understanding of how to interpret pinwheel spinning speeds.

Understanding average wind speed impact on green roof plants also requires some knowledge of the three main photosynthesis pathways termed "C3", "C4", and "CAM" pathways.  The majority of the world's plants are "C3" plants.

C3 plants conduct photosynthesis directly at and beneath the leaf surface in cells called mesophyll cells.  They are highly efficient at producing those substances necessary for plants to grow rapidly because the chemistry occurs on the surface of the leaf where the most sunlight is available.  Yet because C3 plants rely on leaf surface chemistry, they can also be subject to rapid desiccation.

In C4 and CAM plants photosynthesis occurs in a different manner with different cells.  C4 and CAM plants may use a combination of different cells, some deeper in the plant and plant leaf, or in combination with varying times of the day and sunlight amounts, for photosynthesis.

To summarize, C3 plants grow the fastest usually but are also typically more prone to desiccation and wind damage.  C4 plants have a spatially separated protection mechanism embedded in their leaf so they are more wind and drought tolerant yet also grow slower.  CAM plants have stomata that may close under intense sunlight, thereby slowing water loss.  CAM plants too are generally slower growers than the C3 plants.

On a green roof we try and place CAM and C4 plants where the wind is the strongest, using them for wind breaks to protect C3 plants.  Many roofs strictly use CAM plants because of their all around hardiness against light and wind.

Generally speaking, C3 plants are made up of most broadleaf plants.  C4 plants are usually represented by more drought tolerant species such as the grass family and some asters.  CAM plants are generally recognized to be comprised of mainly succulents.

Knowing what kind of wind speed impacts the roof will encounter and what type of plants do best under those circumstances will help with the successful design of a green roof.

Copyright 2014 Kevin Songer

Tuesday, April 15, 2014

Plant Size Considerations for Green Roofs - Size and Weight Are Important!

Sometimes we may be inclined to add small succulents to a green roof planting scheme because we know they may be tolerant to just about every environmental factor encountered on a roof.
Agave are drought, salt, wind, heat and hurricane tolerant, but they will add weight to a green roof!
Succulents can be deceiving with respect to size and weight, especially to those who have not worked long term with these plants and seen their size at maturity.  What may be a tiny, perfectly sized immature succulent may turn into a very large and heavy specimen with age.
Potential Florida Green Roof plant or potential roof problem?
Root architecture too is another important consideration for the green roof designer to take into account.

Some succulent plants develop swollen root tubers for water and nutrient storage.  Additional water means heavier weight.  Moreover, some of these roots grow in a very aggressive fashion and can damage an underlying single ply membrane or asphalt shingle roof.
Potential green roof plants have also have aggressive root systems that can damage single ply or shingles
While some small succulents, like sedum may never grow six feet tall, others can.  Though the succulents and cacti you plant may do wonderfully for the first several years,  over time they may outgrow the roof's planting bed.

Problems arise when these overgrown plants present weight issues with respect to the loading capabilities of a supporting roof structure.  An extensive green roof with smaller plants may weight twenty to thirty pounds per square foot or 100 - 150 kg/sm.  The same extensive green roof with 5' to 6' agaves may weigh three or four times the original weight.

Wind resistant can be another important factor with large plants on a rooftop, especially in hurricane impacted areas.

When you increase a roof's live load fourfold you may cause structural failure issues.

Treat some succulents as potential large shrubs or small trees.  Remember, just because a small succulent looks just right for your green roof doesn't mean it will stay that way.

Monday, April 14, 2014

Green Roofs Can Cool Cities, Learning From an Endurocap

Green roofs really do cool buildings through plant transpiration and I proved this yesterday to myself by example with an inexpensive but highly effective cap called the Mission Enduracool cap.
My Mission Enduracool cap teaches me about green roof cooling effects.
Green roofs and Mission Endurocool cool based upon the same principal as air conditioners  - that of heat being absorbed into a liquid and the liquid transitioning from a liquid state to a gaseous state.

On green roofs and across my cooling cap the liquid is water.  Plants transpire water out of their stomata during the photosynthesis processes and I sweat water and salts.  Air conditioners usually evaporate a refrigerant like freon, but all there cooling processes are based around heat being absorbed into a liquid and the resulting gaseous phase that takes place with heat adsorption.

According to the US Geological Service (USGS) about ten percent of the humidity in the air is due to plant's transpiration.  That is a lot of water!

So because I cycle most everywhere I go, my head (just like a building's rooftop) gets hot from both metabolism and from solar gain.  I always wear a helmet but that piece of safety equipment does not do much to cool except provide a bit of filtered shade.

We have talked of green roofs and their insulation value before, several times in this blog, but cooling offers additional benefits over insulation.  Cooling actually removes heat whereas insulation just blocks heat.

My first bicycle trip out with the cooling cap was to Publix, our local grocery store.  Per the cap's instruction sheet, I soaked it  in water and proceeded to wring most of the water out, leaving the cloth slightly damp.  Snapping it over my bald head I took off down the road after turning my bike's safety lights on.  The cooling effect was immediately noticeable and amazing!

Green roof plants and their transpiration right away popped into my mind.  "Hey!  This is what is happening to a building with a green roof as plants loose water to the atmosphere through evaporation", I told myself.

There are many web resources pointing out the benefits of green roofs, and their cooling potential for the urban core.

For me the maxim, 'seeing is believing' rings so true.  I learn mostly from experience.  The cooling cap taught me yesterday about the power of plants on a roof and cooling the cities.

Riding my bike I felt as if I had an air conditioner in my cycle helmet.

Sometimes short, simple life experiences can teach us more than an entire college course.  Green roofs can cool cities, I knew this before but I am so much more convinced now.

Friday, April 11, 2014

Green Roof Soil Media Questions for an Ocean Front Green Roof

I have been asking myself a question over and over again lately.  How do I keep green roof soil media from blowing off a three story, ocean front residential green roof?

The Atlantic Ocean shore - great place to learn of #Greenroof plants and to build a green roof too!
I think I have the answer but I still am asking myself the question over and over.  Not because I have doubts necessarily, but because I want to examine the issue on a regular basis, over an extended period of time.

In the past I've had new insights arise when I regularly revisit a challenge.  Challenges, be they green roof related or otherwise, are usually solved if one puts enough thought into resolving the issue at hand.

This particular green roof project will be a challenge.  Weight will be a factor as it always is.  Light will be intense and strong, all day long with no shade available.  Salt spray will be constantly coating the plants.  Hurricanes are very likely as the house sits right in the middle of hurricane alley.

But I am as confident as any experienced green roof designer can be that all these variables will  be addressed in a manner that will minimize risk to the structure, plants and surrounding area.

The daily wind factor keeps coming back into my mind though.

Any green roof will have the potential to experience much higher wind loadings.  A green roof on the ocean front usually has much higher velocity daily winds whipping across the soil and plants.  Keeping the plants alive and free from desiccation is one issue and keeping the soil media from sand-blasting a neighbor's house is another design goal (as well as simply keeping the soil media on the roof).

Ocean lots are a challenge to the #GreenRoof designer for many reasons
Sand has it's advantages and disadvantages.  Coastal dune plants, those species that will survive on a roof such as this love beach sand.  But sand has a tendency to be blown around easily and is quite heavy.  The sand here is primarily a lovely brown hue and composed mainly of crushed coquina shell, full of calcium and other trace minerals.  It drains well and holds an adequate amount of moisture.

But I am not thinking sharp beach sand would be good on the roof.  With average daily wind velocities from 5-6 meters per second up to 10 MPS and higher, I am concerned beach sand would be blown away in a matter of days, if not hours.

Walking the beach not only relaxes but teaches much.  I see things on my frequent seashore strolls that remind me of how Mother Nature behaves.  She behaves as she wants too, with little to no regard for us humans and our designs.

Mother Nature and wind has a mind of their own with regards to sand deposition #greenroofs
I view seawalls constructed with many thousands of dollars intended to hold sand in one place or keep sand out of another place and despite our best efforts these structures ultimately always loose the battle. Mother Nature puts sand where her wind blows and in other places too.

Perhaps a larger diameter, lightweight inorganic substance like expanded clay may be better.  We will analyze this in future posts.  A mature, developed green roof plant root system will go a long ways towards holding soil media in place, but can take a couple years or more to for the roots to develop and I don't want the clay to come off the roof and act like shotgun pellets in a tropical storm, damaging adjacent fenestration as ICC notes warn against.

Ultimately, root architecture may be the answer.  Comprehensive root coverage can hold soil media, plants and the green roof system in place even under storm conditions.

Agar-based tackifiers and netting have been used to prevent wind scouring of green roof soil media.  On the ocean front site I am concerned the tackifier would quickly degrade under the intense solar heat and constant salty mist.  Last thing I want to see too, is wind netting loosely flopping about after becoming slightly dislodged, perhaps beating the plants down in the breezes.

Sustainability too and green building programs call for use of local materials and are other considerations to take into account.  Sometimes local material compounding is practical or even the only way to acquire soil media.  Other times local materials may not be suitable for green roof soil applications.

Ocean front #Greenroofs face salt, wind, sun, storms and other harsh impacts
We don't want the soil media to be too dark because of high solar gain.  I spoke with someone yesterday who told me about a free roof that would not grow plants because the expanded shale was so hot he could feel the intense heat through his shoes.

We want the soil media to have a proper, plant friendly pH to encourage good plant growth too, and it needs to be primarily an inorganic mix also.

There are also many standards and reference materials to consult.

European FLL have been the most looked to standards for specification and design.

There is a simple but good short description of the green roof soil media question published by Design Cost Data here.

One of the most comprehensive and helpful discussions of green roof soil media is located on the industry website, .  The article discusses green roof soil media ASTM standards and provides links to other valuable soil media references, especially to an article by Chuck Friedrich entitled 'Don't Call it Dirt!'.

I've got a lot to consider concerning this ocean front structure's windy green roof.

Wednesday, April 9, 2014

Green Roof and Living Wall Soil Media - Vertical Green Begins Below Ground

Vines provide great vertical screening and greening capabilities, especially here in Florida where strong desiccating winds can quickly overwhelm and dessicate a planted exterior living wall,
Coral honeysuckle, Lonicera sempervirens offers interesting color and texture as a living wall
 (unless one uses a non-native invasive species like Boston Fern, Nephrolepis cordifolia, which is never recommended).

One of the most important aspects of creating a beautiful, thick and lush living wall is sometimes never even considered, that being the quality and characteristics of the soil in which the vines are planted.

Unfortunately, many designers only consider the flowers or foliage, forgetting the roots though not seen, are so critical to leaf and flower development.
Native Carolina jessamine, Gelsemium sempervirens should be nice and thick but is planted in bad soil
In urban development projects the soil can be concrete rubble with a high pH.  In situations like these a beautiful stainless and expensive trellis and nice, hot house grown plants can end up looking terrible in a matter or weeks.
Coral honeysuckle planted in poor soils looks terrible
I've written about the Jacksonville Whole Foods living wall trellis system before - an expensive living wall system that looks pitiful, all due to high pH and other soil problems.  Soil pH is a measure of acidity or alkalinity in the dirt.
Living wall vines can become woody without proper soil, loosing their leaves
The health food grocer has a high-quality stainless trellis system installed near the front entrance and on the south side of the store building.  Yet the plants have not successfully established themselves and grown well.  The store has been open now for several years, allowing plenty of time for the plants to send down roots and add  upper biomass.

The present store facility was originally constructed where another building had been demolished.  It appears some of the original slab was reused, and significant amounts of concrete, crushed block and other previous building material was integrated into the soil during site preparation.

Most plants prefer a soil pH of between 5.6 up to 7.0.  Many native and adapted Florida Friendly plants vines require an even lower pH to thrive.

Soils with a high pH, such as the urban soils in the Whole Foods living wall planters, restrict nutrient availability (specifically iron, zinc and manganese), stunting planted vine growth and causing yellowing of leaves.

Although some soil amendments appear to have been added during final landscaping, the type and quantity were not adequate to encourage strong plant growth.

There are several simple remedies available to the Whole Foods site.  The living wall was installed in 2010-2011 and could have easily be supporting massive amounts of flowering, fruiting and beautiful vines by mid summer 2012.  Today it is 2014 and the vines still struggle to maintain a tiny about of leaf cover.

But a remedy is possible.  First there needs to be a minor excavation of existing planter soil, both around the front columns and then within the southern wall planter box.  This soil does not need to be discarded.

Second, an appropriate amount of ammonium based fertilizer should be mixed into the soil.  Ammonium based fertilizers typically contain ammonium sulfate or sulfur coated urea.  Ammonium and oxygen react to form nitrite/nitrate, water and hydrogen ions.  The hydrogen ions then work to acidify the soil.

One advantage urban soils usually have is the variety of soil particle sizes and if not over-compacted, can provide for adequate oxygenation of the soil.  Oxygen and ammonium provide nutrients for the plants and help counteract the higher pH of the urban soils.

A quick field test of the Whole Foods planter soils reveals significantly higher than normal  pH.

Amending with organic matter is another possible approach.  Composted pine bark, pine needles, oak leaves, properly composted food scraps can also release both needed nutrients and hydrogen ions into the soil.  Another benefit of the organic mulch route is that earth worms and other soil life will quickly create extensive micro-communities, contributing additional nutrients and providing for nature based soil aeration.

Once the Whole Foods planter soils are amended with the proper amount of ammonium based fertilizers, the soil can be replaced and plants installed.

Of course, care should be taken not to over-fertilize.  Excess amounts of ammonium based fertilizers can burn the roots of installed plants, creating a whole new set of problems.

Native and landscape vines alike can add vertical interest, privacy, screening, color and texture to a landscape project under almost any atmospheric conditions if they are growing in adequate soils.

Remembering that vertical green begins far below the ground is the first step to living wall design and construction success.

Saturday, April 5, 2014

Antique Louis Philippe Rose on the Green Roof

Check out the antique Louis Philippe rose blooming atop the Breaking Ground Contracting green roof in Jacksonville! @greengcjax


Florida Green Roof antique roses
Florida Green Roof antique roses


Top Ten Florida Green Roof Plants, Salvia lyrata, Lyreleaf Sage

You can not find a better green roof plant than Lyreleaf Sage, Salvia lyrata.  I love to see this very special native wildflower growing across rooftops.

Top Ten Green Roof Plants, Lyreleaf Sage, Salvia lyrata, evergreen beauty
Her evergreen foliage offers an exquisite blend of deep greens, purples and burgundy with leaves laying flat against the ground and flower stems extending vertically to about 18 inches (45 cm).  Note the lyre shaped leaf form.
Foilage - Top Ten Green Roof Plants, Lyreleaf Sage, Salvia lyrata, evergreen beauty
Flowers generally are a deep ocean blue but I have seen the occasional white colored flower populations.
Top Ten Green Roof Plants, Lyreleaf Sage, Salvia lyrata, evergreen beauty
Lyreleaf sage's ability to thoroughly cover open soil media keeps weeds at bay throughout the year.  A mature population of Salvia lyrata can provide a dense, luxurious appearance.
Florida Green Roof Plants, Lyreleaf Sage, Salvia lyrata, thick plantings
Lyreleaf sage transplants easily.  If you can not find the plant in a nursery then it is usually readily found in backyards and alongside the roadside in front of most vacant lots here in the southeast.  Just make sure that when transplanting you are not transferring root-knot nematodes from the ground up to your roof project (though the pests usually can not survive the temperatures on a roof).
Top Ten Green Roof Florida  Plants, Lyreleaf Sage, Salvia lyrata, burgundy and green
This special plant will provide you with many surprises.  She will be green most of the winter when other plants have that sleepy brown appearance and provides masses of bee and other pollinator attracting blooms when most other flowers are still just thinking about blossoming.
Top Ten Green Roof Plants, Lyreleaf Sage, Salvia lyrata, evergreen ground cover
Check out our previous posts about this special plant.  Read the Seeds for Green Roof Post about her also!  Planting this extremely hardy and drought tolerant species will pay off in big green roof successes.

Thursday, April 3, 2014

Green Roofs, Rooftop Permaculture and Marketing

Check out this cool website using #GreenRoofs and Rooftop Permaculture as a backdrop to marketing their clothing line.  I like it!

Green Roof Plants, Rain-Root Zone and Root Architecture

One of our favorite Florida #Greenroof plant Genus is the Allium genus.  We've also been working with Resurrection fern also - and I love this plant.  Resurrection fern,  Polypodium polypodioides, was the first fern in space - going up on a 1997 Space Shuttle Mission to see if the roots would absorb water in a space capsule.

Green Roof Plant Root Architecture - Florida Extensive Green Roofs - MetroVerde
Both of these plants, the Allium and R. fern can have unique root characteristics, depending on how they are raised by the grower.

We call plant root structure by the name - 'Root Architecture'.

Green roof design has unique root structure and root architecture requirements.

Unless you have an unlimited potable water or well water source and are going to pump all that water up on a roof to keep plants up there watered, then your green roof plants need to be somewhat drought tolerant.

Certain root architecture patterns support plant acclimation to drought conditions better than others.

Remember, Florida's rainfalls usually are short, afternoon events of 1/2" or less and because rain generally occurs between the hotter months of the year - June - September, there is a tendency for it to evaporate quickly.

Except for hurricanes and tropical storms, rain events in Florida are usually over relatively quickly.

Meaning green roof plants have to scramble to grab the rain water.

Also recall, most green roof plants do not like wet roots (wet feet) so the soil must be well drained.

Proper green roof plant root architecture is crucial for providing a Florida extensive green roof plant with the advantages needed to survive a Florida vegetated roof.

Examine the diagram below showing the root architecture of a green roof plant raised in a one gallon standard nursery container and then a green roof plant raised in a built-in-place green root extensive planting bed.

The plant raised on the built-in-place green root extensive planting bed possesses 8 times the amount of Root-Rain surface contact area as the same size plant grown in a nursery container.

So when the afternoon 1/2" rainfall (13mm) event occurs and every drop is important - the green roof plant with the appropriate root architecture will sequester the most water.

More stormwater is captured, runoff is reduced, plants acquire necessary water volumes, plants have less of a tendency to uproot in high winds, and more.

Green Roof Plant Root Architecture is important to the success of a green roof.

Evergreen Florida Living Wall Vine, Trachelospermum jasminoides

Here is an nice example of how vines can be used in tropical climates to create expansive living walls.

Florida living wall vine, confederate jasmine, Trachelospermum jasminoides

Growing in sunny Orlando, Florida, the confederate jasmine vine, Trachelospermum jasminoides looks to be about 50 feet tall (15 meters).  The vine has grown very woody and thick over the years at the base but still is relatively full and green from just above the vase up to the top most portion.

Florida living wall vine, confederate jasmine, Trachelospermum jasminoides
Confederate jasmine is a reliable landscape vine though it is not a native plant to the Florida area, however the University of Florida classifies the plant as a Florida Friendly landscape plant.  Importantly, unless the plant is installed in properly amended growing media, it may struggle.  Many times I have seen confederate jasmine installed in non-amended urban soils with concrete debris and high pH soils and in these instances it has struggled to establish itself, sometimes looking ragged in leaf appearance.

But once the plant begins to grow, it provides significant, evergreen foliage cover and fills the air with perfume-like scents when the flowers bloom during springtime.  This specimen was growing up and across a very heavy-duty appearing metal pipe and channel trellis.  A smaller, less sturdy system may have a hard time holding the weight of this mature vine.

I did take note of the building owner removing a grouping of old established confederate jasmine vines from another section of the building.  It is possible that because of the educational efforts of local, state and regional native plant groups that the vines may be replaced with native evergreen flowering varieties such as coral honey suckle, Carolina jessamine of others.  I personally prefer using native vine species for Florida living walls, both decisions and evergreen depending upon the application and whether solar gain issues come into play.

Living walls seem to do much better here in Florida if they are vine based, rather than vertically planted ornamentals.  The 5 H's of hurricanes, heat, humidity, hard frosts and high winds act brutally upon vertically planted ornamentals here.  Vines, on the other hand seem to adapt nicely to creating Urban Core Vertical Green if, as mentioned, the soil is amended appropriately.

For an interesting look at a very expensive living wall trellis system with struggling plants, read our series of posts here, pointing to the importance of properly amending urban soils before planting living wall vines.

Tuesday, April 1, 2014

Biodiversity, Habitat and Florida Urban Green

Vertical green in the urban core is so important for biodiversity and habitat.  Unappreciated weeds have significant ecological value.  Here is a short clip about 'weeds' growing in concrete and wildlife.

Imagine if the sides of bridges were intentionally landscaped as part of construction!

Saturday, March 29, 2014

Florida Green Roofs and Hurricanes, Storm Season is Fast Approaching

The Eastern Pacific Hurricane season begins soon and the Atlantic Hurricane season follows shortly thereafter.
Routine green roof maintenance and hurricane inspections are important for Florida Green Roofs
Hurricane design is an important consideration for green roofs.  If a green roof is to be built in areas subject to hurricane or cyclone impacts then a few simple guidelines will help make the design more resilient against wind and storm damage.

At a minimum, we recommend;
  1. No large trees on a roof.
    1. Small shrubs and small trees may be used successfully depending upon the final design.  This may seem like a common-sense guideline but people try to put all types of tall, large trees on patio or garden roofs.  During a 130 mph cyclone, the tree may be blown over and may cause damage from the fall against the structure or to the street below.  It may also become airborne if the winds are strong enough.  Growing up in Hialeah I saw plenty of hurricanes come through our area and witnessed first hand the power of these storm events.
  2. Anything and everything on a roof should be permanently attached.  
    1. Walkways should be constructed from a permanently attached TPO, EDPM or other mat and permanently affixed to the roof.
    2. No loose chairs, tables or other items should be present.  If you wish to have a chair and table stay on a roof during a cyclone, they must be permanently attached.
    3. All green roof components must be permanently attached to the structure.
    4. Any trays, plastics, pots, containers or other green roof components must be permanently attached to the building structure.  Florida Building Code does not allow for loose items to be installed on a roof - they must be attached.
    5. Green Roof Irrigation components must be permanently attached to the roof.
  3. Make sure all tools and gardening utensils are picked up and put away.
    1. It is very easy to forget the pair of shears, scissors or pliers on a roof.  Remember what you were using and where you liad them.
  4. Plant selection should be focused on those species that have historically survived cyclone and hurricane incidents.  There are several good books available at most bookstores here in Florida on proper cyclone resistent landscaping and many resources on the web, such as the Brevard County Landscaping Guide for Hurricane Areas.
  5. Check on the NOAA National Hurricane Center website daily.  The NHC webpage is a wonderful resource, full of links to climatic data.
Always use a green roof design or green roof system already proven in actual field trials with hurricane simulation testing.  Watching a green roof blow off during a storm is an avoidable event.  Due diligence upfront and preparedness is important for green roofs in hurricane prone and cyclone impacted areas.

Thursday, March 27, 2014

Safety First on Florida Green Roofs

Most of the time when we talk about Green Roofs we discuss plants, irrigation, soil media or other technical aspects of creating a living, thriving ecosystem on a rooftop.  Life on top  of a building is so important for the survival of cities.  Life is also important to each of us, our friends and families.
Green Roof safety gear, Metroverde hardhat, vest and safety glasses.  Safety first on a green roof!
Roofs present fall hazards and green roofs do also.  A fall from the roof can seriously or even fatally injure a worker or invitee.  Green Roof safety is of paramount importance.

Thanks to Tad and Jimmy of Sterling Roofing for the recent and ongoing educational opportunities about safety first on a roof and for the hardhat, vest and personal safety glasses.

When I visit a site I am basically prepared to walk through construction (including my safety toe boots) with my hardhat, safety glasses and bright orange vest.  A construction site poses many risks.  Adequate safety rated personal protection gear is essential.

Up on the roof I will always make sure I am protected by guardrails, personal fall protection gear or safety nets.

Importantly, the construction job must have a safety plan in place and entering a job site without the proper protective gear can result in OSHA citations, fines or removal from the job site.  This is all for one good purpose - to prevent unnecessary injuries.

I've created a safety first page here on the Florida & tropical Green Roof web blog.  Check out some of the interesting videos about working on a roof and personal fall protection systems.  There are also links to suppliers, such as Grainger's, Personal Fall Protection Systems and anchors or Gempler's Fall Protection and Rooftop Safety PDF Tip Sheet!

Know your local, state and OSHA safety rules.  Discuss your safety plan with your insurance agent.

Never work unprotected on a green roof.  Never.

Always follow safety rules when working on a green roof.  Beautiful rooftop blooms are so much better than terrible statistics.  Safety First on the Green Roof!

I'd love to hear your thoughts about safety first on the rooftop!

Wednesday, March 26, 2014

New Green Roof Project, Florida - Sneak Preview, Roof and Plants

A new green roof project here in Florida!

Roof: 5% slope with a 6" parapet in a highly windy area. Approx: 1800 SF
Florida #GreenRoofs: Dry in awaiting single ply membrane and hurricane green roof system


  • Cymbopogon citratus, lemongrass
  • Yucca filamentosa, Adam's needle, and
  • Tripsacum floridana, dwarf Fakahatchee grass
Cymbopogon citratus, Lemon grass at the grower awaiting planting
Lighting: TBD

Sneak preview :)

Tuesday, March 25, 2014

Green Roof Scaled Design Mock-up Sample for Upcoming Florida Green Roof Project

For Florida green roofs, coastal green roofs or any type of #GreenRoof projects, many times it is a good to build a scaled version 'mock-up'.  A scaled version looks so much different that the design does on paper.
Florida Green Roof design sample, mock-up (see pdf) rated for hurricanes, heat & humidity
And small green roof scaled, mock-ups can help the designer anticipate successes and also challenges and show the client what they can expect.

A client requested this particular mock-up going to be built on a cafe in Orlando.
Sterling Roofing of Jacksonville staff assisting in the construction of Florida Green Roof scaled mock-up
The slope is approximately 5% and the soil media comes from a local source.

Plants are a mixture of native grasses, lemongrass and native succulents.  The native succulents will be planted closest to the back vertical wall to comply with ANSI Green Roof fire standards.  Check out posting of the ANSI Fire Standard for Green Roofs by scrolling down to the Resource link on the MetroVerde website green roof design link.
Green Roof Florida, scaled design sample build
Next time you anticipate doing a green roof project you may want to consider building a similar mock-up of your proposed design.  We find this effort well worth the time and cost.

Sunday, March 23, 2014

Florida Green Roofs and Biomimicry, Agavaceae and Dew

Nature offers the finest examples for us to look to when resolving green roof, or any other for that matter, issues.  Today I want to mention plants that catch air moisture, such as dew, and help 'irrigate' a green roof.  Let's look at some of my favorite green roof plants, Yucca and Agaves.
Floria extensive, sloped green roof
Green Roof Plants, Yucca and Agaves - note the hairs and clover, a nitrogen fixer
Yuccas and Agaves, with hairs across the surface edges of her leaves is a highly efficient fog and dew catching plant.

Likewise, with waxy, tough leaves and CAM (Crassulacean Acid Mechanism) photosynthesis, they can serve as the perfect green roof edge wind-break perimeter plant.

Yucca and Agave biomimicry tells us high dew catcher surface area to air mass contact is most efficient for air water vapor to occur. 

Many yuccas and agaves thrive in hot, dry, windy areas and make excellent choices for green roof plants.

Yucca filamentosa, Adam's needle is a favorite green roof plant of mine, reliably hardy in the freezing cold temperatures, evergreen, very drought tolerant, a dew catcher and the perfect CAM perimeter plant.

Yucca filamentosa makes an excellent green roof plant for Florida
Planted in mass, Yucca filamentosa acts as a green roof parapet, allowing interior plants a more welcoming ecosystem for growing.  This green roof plant has not only survived, but thrived on some of our older green roofs!

Yucca filamentosa also has long hairs growing from the leaf edges, allowing for water vaopr in the air to collect as the humid breezes flow across the plant.

Turbulence is another factor necessary to help drop the condensed air water vapor from the catcher to the green roof soil below.

Florida Green Roof  Plants Yucca and Agaves, Note the hairs along the plant edges that facilitate dew sequestration

Success of a nature irrigated green roof depends heavily on sourcing a steady supply of water through rainfall, fog, dew and even frost. Understanding biomimicry based green roof planting layout allows for important air water vapor collection.

Additionally, understanding the principles behind Agave's and Yucca's' water capture successes lie also in an understanding of air humidity.  Humidity is the amount of water vapor in the air. 

Humidity is an important source of irrigation for nature irrigated green roofs and is often present when rain is lacking.  Humidity is often described in terms of ‘relative humidity’ and ‘dew point’.

Relative humidity is the phrase commonly used by weather reporters to communicate the percentage as the amount of actual water vapor in the air divided by the amount of water vapor the air could hold. 

A relative humidity of 75% means air contains 75% of the amount of water vapor possibly held.
Yucca acts as a dew catcher to provide moisture to other Florida green roof plants

Dew point refers to lowest air temperature where water vapor remains in vapor form.  Once the ambient air temperature reaches the dew point temperature the water vapor condenses into dew or liquid.

Dew and fog reference and collection resources available on the web include;
  • is a great informational resource on capturing dew and fog 

Air humidity can be a significant component in the irrigation of any green roof system.  Consider those months with lower than average precipitation and check to see if dew occurs frequently.  Validate the average relatively humidity percentages.  

Think of the times you have walked across a lawn in the morning to find your shoes soaking wet.

Research dew and fog collection websites.  Look to the green roof plants you work with to see what species appear to accumulate dew. 

Mimic nature.  Mimic the Yuccas and Agavaceae.

Saturday, March 22, 2014

Green Roof Benefits for Florida; Cleaning Air Pollution, Battling Cancer and Other Respiratory Diseases

Green roofs and living walls can help clean the air and allow us to breath easier.  They can also keep us from becoming sick or ill, even contracting cancer.
Florida Green Roof Plants are the Ultimate Fresh Air Source & CPR System
Today, many geographic locations across the globe have air contaminated with Volatile Organice Compounds also known as VOCs.

Florida Green Roof Plants Clean Air & Remove Pollutants
Volatile Organic Compounds (VOCs) are chemicals created by industrial pollution and automobile engines among other processes.  VOCs are the primary cause of Urban Smog. 
They are also responsible for the formation of cancers, respiratory problems and other serious health issues.  Just think of the times you have seen city smog envelope an urban area, filling the area with obnoxious and dangerous particulate matter.

According to the US EPA, the Health Effects of VOCs include:

Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, dizziness.

Even our children understand the importance that plants play in cleaning air, see: .

The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic, to those with no known health effect. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes. Many organic compounds are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans.
Green Roofs in Florida not only provide clean air to humans but to wildlife also
For more health information on VOCs from the EPA click here. 

According to a new study - one confirming what we already know - plants -  - clean these harmful VOCs out of the air.   Read about the study in a National Science Foundation Article here.

This study makes it clear that it is especially important to have as many plants inside your building or home as the levels of VOCs inside a structure can be up to ten times the ambient levels outside.

Green roof plants can save our respiratory systems!

Plants act as filters for air and rainfall, actually removing and utilizing harmful nitrogen.  They also remove carbon from the atmosphere by using CO2 to produce much needed energy compounds and then plants pump oxygen back into the atmosphere.

Some have said that for every twenty thousand leaves in a city (a small tree - for an interesting note on how many leaves are in a tree see: )enough oxygen is produced each day for one person to breathe clean air.

As we are bombarded with pollutants each day, in our water and in the air - installing interior living walls, exterior vertical green - green roofs and living walls, Urban Permaculture - City Gardens, wildflowers and trees - can pay off with significant benefits.

Ultimately, we may live longer.  Ultimately, we may beat the odds with cancer or respiratory diseases.
Green Roofs in Florida clean air and can grow food
Restoring Volumetric Green to the Urban Core is critical.  Today, go out and plant a seed or a grown plant.  Bring another inside.  Hang plants from your patio walls and your kitchen window.  Keep plants in your home.  Install a green roof.

Green roofs and living walls - cleaning stormwater, creating habitat, providing a sense of place and beauty and - importantly - fighting disease by removing pollutants!

Surround yourself with plants today.  You may breath better and live longer. 

Remember, the benefits of adding volumetric green to the Urban Core include;

  • Cleaning Rainfall runoff and stormwater
  • Providing wildlife habitat
  • Supporting biodiversity
  • Creating habitat for endangered plants
  • Integrated pest management - supporting pest consuming invertebrates and amphibians
  • Noise insulation
  • Reducing Heat Island effect
  • Creating a Sense of Place and Landscape Beauty
  • and more