Sunday, November 30, 2008

Choosing Plants for Green Roofs - The Season for Sedums to Die in Florida

Tis the season for some sedums to go dormant in Florida....

We have had a month of drought. The days are becoming shorter and shorter. The winds are brisk and desiccating. Temperatures have ranged from 60 to 80 degrees F during the day and 30 to 60 degrees F at night.

We have had three light to medium frosts.

Too much for some of the sedums...

The alliums are turning brown on top too - the brown curly cues typical of drought.

The Florida climate is the biggest drawback to using sedums on Green Roofs - at least don't count on the succulents being your prime plant...

They usually come back out in the spring.

Happy green roofing!

Monday, November 24, 2008

Green Roofs use of Expanded Clay and Lightweight Expanded Clay Aggregate

The State of Florida has recently requested studies analyzing the use of gravel and aggregate on roofs and the potential of gravel ballast to break windows and other fenestration components of a building during hurricanes.

Preliminary research by the University of Florida shows that gravel ballast may be the cause of unnecessary glass failure and subsequent water damage.

Hurricane Alicia in 1983 devastated the Houston area, and much of the urban fenestration damage was attributed to gravel ballast ripped off the roofs by the hurricane force winds and shot across the city like pellets.

As Florida's green roofing industry develops, designers should be aware of the potential for tort damage liability once their specified product damages anothers property.

We should be careful about placing any gravel or pellet like material in a green roof until all the appropriate studies have been conducted to determine the level of safety for such product use.

Wednesday, November 19, 2008

Frost & The Florida Green Roof

Tonight is the second night of the November 2008 winter where the outside temperature is expected to drop below freezing. Last night there were low in the mid to low 20's all across North Florida and the same is expected tonight.

Expected seasonal weather like this creates a huge challenge for the vegetated roof designer in Florida. Not just cold weather alone - because many northern green roofs survive much colder temperatures.

No - it is the combination of two weeks ago we were experiencing heat and humidity at high levels and now the frost - little if any hardening off of the roof plants.

I pose a question here. What happens when many of the native plants here that are deciduous or produce leaf litter - what happens when leaf matter dies from frost or drought? One of the answers is that we see a marked increase in leaf litter buildup.

Leaf litter turns into fuel once ignited. Dead plant matter, dried by desiccating cold winds can easily and rapidly burn when exposed to a spark or heat source.

Fire occurs in nature to cleanse dead plant matter from the environment and return nutrients to the soil. The chance of a roof fire increase once flammable, dried leaf litter accumulates on a green roof.

ASTM has recognized this potential problem and is developing standards for green roof plants.

The good designer will also strive to incorporate plants that prevent or greatly reduce the chances of leaf litter build up.

As we enter the season where many plants are dropping their leaves and becoming dormant, we should ask ourselves as we design green roofs, about potential fire issues with the plants we are selecting.

Better safe than sorry.

Monday, November 17, 2008

Green Roofs in Florida and the Southeastern US. Insulation values for real?

We can all assume that thick intensive green (vegetated roofs) provide a measure of insulation - but what about thinner, extensive green roofs? Do extensive green roofs, say 2 to 4 inches thick provide insulation benefits?

Jincy, Ruairi and I have tracked the insulating factors of several extensive roofs, comprised of the MetroVerde mat roof system during the 2008 summer season.

What we found was very interesting.

Using a Extech Infrared IRC40 thermal imaging unit we measured the temperature of the roof decking undersides for roofs with (A) extensive 3" thick mat based vegetated roofs planted with allium and iceplant, and (B) asphalt shingle covered decking.

Not surprisingly, the underneath of the roof decking on asphalt shingle roofs averaged 125 - 130 degrees F during July, August and September 2008.

Temperatures of the undersides of the roof decking below asphalt shingles covered with the MetroVerde extensive mat systems averaged 84 - 86 degrees F at the same time of day.

Moreover, it is expected that the green roof mat system will protect the asphalt shingles from solar degradation.

So do extensive green roofs insulate a roof from solar gain? The answer is an undeniable Yes!

Green Roofs in Florida and Cooler Weather

It is becoming cooler and night now and well should be - it is almost Thanksgiving & most green roof plants on our projects are very happy that the long and tortuous ordeal with Florida's heat and humidity is almost over for a season...

Many of the plants bear battle scars from Tropical Storm Fay (way, way too much water) and the ever present afternoon humidity bath.

The Sempervivums are starting to can see new growth expanding out from the middle of the plant, the brown, wilted areas falling away from the perimeters.

This is the time of year for dormancy for some of the sedums - - they are turning brown and melting away while others are just melting after a long stressful battle with the Florida humidity.

Iceplant is doing well. Iceplant planted on the ground melted out during T.S. Fay but those clumps on the roofs actually thrived.

Interestingly, the allium likes the cold weather too - its leaf blades perk right up.

So now is a major time for seasonal change in North Florida for green roofs. Stay tuned for more updates!

Friday, November 14, 2008

Green Roofs in Florida -

Palms and/or other trees on roofs present many challenges to the designer. In Florida these issues can include: (1) weight, (2) wind speed uplift during tropical storms or hurricanes, (3) irrigation and maintenance requirements, (4) fire safety and more.

Though I focus on thin, lightweight Green Roof mats (much less expensive) there will be clients who would like to have a roof with trees. Certain challenges are presented to us in designing a roof capable of supporting trees. First and foremost your structural engineer has to provide a deck capable of handling the loading.

We will be collecting photos of Florida green roofs that include trees and large shrubs. Send your photo in to Kevin for posting - along with a description of the roof, location, how long the roof has been in existence and other data.

Holidays are coming up - what better way to celebrate than with a blooming green roof!


Monday, November 3, 2008

Green Roofs can be vertical green vines also - Choosing the right plant and planting system lays the foundation for success.

Try a MetroVerde Shade Trellis! Based on the concept that a deciduous vine will block solar gain during the summer when the leaves are growing and allowing needed heat during the winter months when the leaves are off - MetroVerde's shade trellis combines plant requirements with awning frame design to produce a product that 1. cleans stormwater, 2. provides habitat and 3. creates a beautiful sense of place!

Green Roofs - Another Volunteer Vegetated Florida Roof

Walking the streets of almost all cities and towns you can see plants growing in the toughest of places.

They grow in the cracks between the concrete in the middle of the busiest streets and interstates. They grow up walls, peaking from the tiniest of crevasses. The grow in gutters and in roof seams. Give a plant a chance and many species will grow just about anywhere there is a little sunlight and occasional water or moisture.

The philosophy we carried with us over the years of experimenting with how to successfully grow plants on roofs was simple. It was based on watching plants grow in the most inopportune places.

Our goal was to design a vegetated or green roof that inherently had the following characteristics: 1. Low weight, 2. Reasonable cost, 3. Leaves and color all year, 4. fire resistant, 6. heat, humidity and hurricane resistant, 7. Florida Department of Community Affairs approved, 8. treats stormwater, 9. provides habitat for wildlife, 10. was low maintenance, 11. could be used on slopes (we can go vertical), and finally - a roof that would last - season after season.

We believe we have developed what we set out to do!

Call Judy at MetroVerde - 904-294-2656 to find out more about your new green roof!

Sunday, November 2, 2008

Check out this Website - Living Houses! Living Group Designs and Plans Review by Karl Wilson

Wow! Karl Wilson revealed a set of Green Parking Garage plans and I met two green architects - Alain Dezii and John Szerdi this week. Their Architectural firm in Fort Worth is a living building - all the gray water is treated in modular interior wetlands and the only potable water is used in the faucets.

The open air plenum system keeps the 4 story building amazingly cool!

They even have roof gardens - with native grasses, palms and more!

Think of Alain and John when you need a green, living building design! Check out their website!

Think of Karl's solar panel shaded parking garage roof with living walls when you think institutional, medical or parking garages! Check out Karl's website!