Frequently Asked Questions
What is the cost of a vegetated roof?
The cost of any green roof is the sum of four costs: acquisition, maturation, maintenance, and life cycle. If one fixates on low acquisition cost, they are likely to get stuck paying for high maturation expenses, high ongoing maintenance costs (ongoing headaches), and a high life cycle cost (with a system that is short lived). With LiveRoof, that is not the case—we deliver quality, beauty, and long term value.
What is the biggest financial advantage of LiveRoof?
Extension of the lifetime of the roof; typical estimates are that a green roof potentially extends the lifetime of a roof between 200 and 300 percent, by protecting the rooftop from ultraviolet radiation, large temperature fluctuations, drying winds, and punctures. Not only does the roof last longer, but there is reduced membrane maintenance. All this brings about significant cost savings over time. In some communities, storm water incentives may also bring substantial monetary benefits.
Energy savings - What Can I Expect?
Green roofs have been proven to bring about significant energy savings, particularly during the summer cooling season in which single story buildings can experience a reduction of greater than 25% energy use for air-conditioning. Green roof soils insulate the roof from heat, and green roof plants transform heat and soil moisture into humidity, to create natural evaporative cooling. Each gallon of water transpired by the plants or evaporated from the soil surface liberates 8000 BTU of thermal energy.
Why doesn’t the LiveRoof system use filter cloth?
Filter cloth, like any filter, is designed to filter. Filters in time can plug up (think of your car’s air and oil filters, your furnace filter, coffee filter, etc.). If a green roof filter plugs up, then what? Because of the aggregate nature of LiveRoof soil, very little soil escapes the LiveRoof module. It’s like trying to push marbles through a funnel or a square peg through a round hole. In addition to this simple act of geometry, the roots of the LiveRoof plants bind the soil together and hold it in place.
What’s so special about LiveRoof soil?
Unlike cheap soils that are marketed as light weight, and packed with peat moss and perlite, LiveRoof® soil is composed of approximately 94% high quality inorganic aggregates (by dry weight), contains a special clay particle to bind nutrients (incorporated in most regions), contains an acid rain buffering component, and is formulated with disease suppressive organic material at a level that is consistent with ecologically sustainable soil/plant communities. LiveRoof soil is designed to last indefinitely and to not substantially shrink over time. Cheap mixes with high levels of peat and compost will decompose and wash away as humic acid. Perlite after several freeze thaw cycles may shatter repeatedly and turn to dust. It may also float to the soil surface after heavy rains, then blow away when conditions are dry and windy.
Why are frequent, brief maintenance activities critical to success?
The life cycle of most weeds is about four weeks. Therefore, by weeding every 2 weeks, for just a few minutes, the few weeds that come from birds and the wind, are not allowed to reproduce (and become many). This is the "smart" way to manage a LiveRoof, and it is what allows one to have a pristine LiveRoof with almost negligible maintenance costs.
Can I retrofit an existing building?
It depends on the load capacity of the existing building. Also,some older buildings can be redesigned for the additional weight of the LiveRoof modules. The LiveRoof Lite system at 15lbs. to 17lbs./sq. ft. often times may be the best choice for retrofit applications. A qualified engineer should always conduct a thorough structural analysis.
What is the urban heat island effect?
Simply put, it is the temperature difference that exists between urban areas and their surroundings. Urban areas tend to be from 7 to 10 degrees hotter due to the concentration of heat-absorbing buildings, pavement, auto exhaust, and hot air from cooling systems. The bubble of hot air that encloses cities is in large part due to lack of vegetation and is a great contributor to smog, ozone and dust (from artificially created air currents from the rising hot air). The urban heat island effect has also been shown to create unique weather patterns, with inordinate drought, high winds and electrical storms. How does the LiveRoof® system help mitigate the urban heat island effect? Traditional rooftops are usually covered with tar, black membrane, shingles or stone. As a result, they absorb sunlight. On sunny days with an air temperature of 95°F, city roofs can easily reach temperatures of 175°F or more. The LiveRoof system acts like a protective umbrella above the roof to shade and insulate buildings, avoiding the heat island effect associated with traditional rooftops. Plants, of course, release oxygen and evaporate water, and the soil they live in evaporates water. Collectively these processes are known as evapotranspiration and act like evaporative cooling systems to make the surrounding air considerably cooler. By implementing a LiveRoof system, the combined benefit of eliminating the heat generated by a non-vegetated rooftop, along with the evaporative cooling effect, is significant.
How does the LiveRoof® system reduce storm water runoff?
In urban areas, impermeable surfaces (streets, sidewalks, rooftops etc.) dominate the landscape, preventing rainwater from following a natural cycle of absorption. Instead, as much as 75% of the rainwater runs into sewer systems carrying contaminates from the air and roadways (salt, oil, mercury, etc.). This water flows untreated into lakes and streams. In some cases, it may cause overflows of sanitary sewer systems, causing the dumping of untreated sewage (combined sewer overflow). In contrast, LiveRoof® green roof surfaces can absorb a substantial amount of rainfall, reduce runoff, lessen the risk of combined sewer overflows and flooding, and to some degree filter the water as it percolates through the LiveRoof® soil. Even when a rainfall is such that it can not all be absorbed by your LiveRoof®, the excess rain that runs through the growing medium is filtered and delayed until after peak flows, which allows additional time for sanitary sewer systems to handle uncontrolled runoff.
How does the LiveRoof® system reduce noise?
Plants, soil, and trapped air and moisture in the soil are great acoustic insulators. Studies have shown that green roofs can reduce indoor sound by as much as 40 decibels, a benefit not lost on those that work close to overhead highways and airports.
Where can the LiveRoof® system be used?
LiveRoof® is most commonly used on well drained, low- and mid-sloped roofs, on industrial, commercial, institutional, governmental and residential buildings which can support the weight of the green roof system. Green roofs should only be applied to appropriately engineered buildings.
Can I lift up a LiveRoof® module if I want to access my roof?
Yes, it’s relatively easy. First, using a flat bladed shovel, probe the planting to locate the container edge. Then peel away plant material around the edges of the module. This is easy to do as the root systems of succulent LiveRoof® plants are fibrous and easy to separate (not at all like sod). Using a sturdy pair of pliers, lift up and remove the exposed module. Any additional modules may be removed by trimming around them with the handle of a spoon and lifting them up. Once you are finished, replace the modules. Note: Never use sharp instruments around roof membranes.
What incentives are available for green roofs in Texas?
In acknowledgement of green roof benefits and to encourage their widespread use, the City of Austin offers a number of incentives for projects incorporating living roofs. Implementing a green roof in Austin will contribute to accumulating points via the Austin Energy Green Building Rating System. This is important to making our city a more progressive and sustainble place to call home. In addition, you will also receive credits for stormwater management, open space, and impervious cover. We believe the biggest incentive lies in the Downtown Density Bonus Program (§25-2-586). Essentially, square feet of bonused floor area is earned for each one square foot of planted bed provided on a vegetated roof. To see if you qualify for this credit, follow the link below to learn more: City of Austin Credit Fact Sheet
Can the LiveRoof® system be used in nonroof areas?
Certainly—median strips, patios, plazas, and malls are also great opportunities to use the LiveRoof® system.
Can LiveRoof® modules be cut to fit odd dimensions and angles?
Yes, LiveRoof ® modules can be cut to size and shape with the use of a masonry saw or reciprocating saw. When installing custom cut LiveRoof ® modules, the cut side should abut the non-cut side of another module, in order to contain the soil and minimize the work of installation. If the cut side ever abuts edging, it should not be edging that is located on the low, draining side of the roof. Always fit modules tightly against edging or parapet or surround with drainage fabric for added security.
Can LiveRoof be used in elevated planters?
Yes, normally this is done on rooftop patios where the load limits do not allow for the weight of 2 or 3 feet of soil in the planters. In this case, all but the top 4 1⁄2 to 6 1⁄2 inches of the planter is filled with closed cell foam, then LiveRoof is set on top to give the illusion of substantial soil volume.
Can I walk upon my LiveRoof plants?
Yes, but sparingly. One person can do this a couple times a week without causing permanent harm. However, you must avoid walking in a single path or standing in one place or trampling your plants. If you must service a wall or parapet you may cover the plants with plywood or closed cell foam for up to 4 hours provided foliage is not wet and conditions are not too hot or sunny. It is especially important to avoid repetitive foot traffic when plants are wet or frozen.
Can I use de-icing chemicals on my LiveRoof plants during the winter?
No, LiveRoof plants are damaged by de-icing chemicals. If your LiveRoof is adjoined by pedestrian walkways, you should use sand or cat-litter as an anti-slip measure after shoveling.