[Greenbuilding] Modular Green Roof Tray Manufacturers.

[Chris Green]

There appear to be two manufacturers (so far) of modular green roof 
trays in North America.

The smaller system of trays which have the 2'x2' size ends up with about 
80+ pounds load on each 4 square feet at 20-26 libs/ square foot. The 
trays are placed so they touch each other.
The trays can be 4 to 6" deep but you don't have to fill the tray to the 
top.
GreenGrid must be the supplier mentioned in the FimeHomebuilding video. 
They appear to have supplied a lot of installations done in Chicago, 
"The Windy City".
http://www.greengridroofs.com/system/index.htm

GreenTech offers larger trays, (8" x 48x48' for a net volume of about10 
cuft -- heavy suckers.) with built-in pallet slots for moving with 
either a small forklift or a pallet jack. They also have done 
installations in Chicago.
http://www.greentechitm.com/systems/roof.asp
Moving 80 pound loads around to check for damage is obviously going to 
have to be kept in mind when designing the system. The larger ones, 
which weigh from 26 to 41 psf (depending on soil mix) definitely will 
need a pallet jack, and more room between rows to move things around.

One can contact the folks in these companies and have them address the 
risks with using modular trays in high wind situations.

To be fair and balanced in reporting, this site is critical of modular 
systems like this:
http://roofmeadow.com/technical/mb4.shtml

Also:
>
> 3. Wind Resistance Systems
>
> Due to the unique physics of the green roof profile, attaching the 
> elements of the green roof to the underlying structure is not usually 
> important. The biomass bonds with the fabrics to create a unified 
> cover, and the plants themselves create enough surface wind turbulence 
> to foil potential uplift—the converse of an airfoil. If the green roof 
> will be located in an unusually-high wind area, such as a high-rise 
> building or a coastal region, appropriate ballasts should be 
> specified. Guidelines for ballast requirements are available from 
> European green roof providers <http://www.optigruen.de>.
>
(I couldn't find the "Guidelines for ballast requirements" mentioned: 
maybe someone else will be luckier. There are 100million+ sq. ft of 
green roofs in Europe so far, and although Europe doesn't seem to have 
picked up on the 4-year old modular tray system yet, someone there must 
have a handle on what is required to prevent these things being picked 
up and blown away )
>
> 4. Modular Systems
>
> Modular systems involve installing the green roof system inside 
> plastic trays. Use of these systems does not relieve the designer from 
> responsibility for considering the integrity of the underlying 
> waterproofing system, nor does it make location of damaged 
> waterproofing easier. However, these systems can be useful when 
> designing small gardens on residential property or terraced commercial 
> roofs. They also preserve flexibility to re-arrange landscape designs 
> in the future. Owners who wish to engage in active gardening will find 
> modules a convenient way to do this without damage to their homes' 
> waterproofing. Two companies in North America currently offer modular, 
> or tray, components, GreenTech <http://www.greentechitm.com> and 
> Weston/ABC Supply <http://www.greengridroofs.com>.
>
> 5. Electric Leak Detection
>
> Inexpensive methods for locating damaged waterproofing underneath 
> vegetated covers are available. These include the electric field 
> vector mapping (EFVM) <http://www.leak-detection.com/efvm.html> 
> procedure. This method works by charging the moist media layer of the 
> green roof with electricity and then looking for electrical grounds 
> caused by moisture in contact with an underlying steel or concrete 
> deck structure.
>
This last bit might be worth filing away.
Source of quoted text:
http://www.wbdg.org/design/greenroofs.php

Paths between the modular trays could be built using a system of 
interlocking "geogrids" like the EcoGrid system offered here:
http://www.terrafirmenterprises.com/

In closing, I wonder just how much wind is required to lift that much 
weigh off the roof, especially if the aerodynamics of the 
microenvironmnet (allegedly) work against the the uplifting forces?

Anybody happen to have a wind tunnel they're not using? :-)

Even with these systems, the requirement is still there for properly 
installing the waterproofing membranes and whatever else is needed for a 
more traditional GR.

Cheers,

Chris Green.