FREQUENTLY ASKED QUESTIONS & ANSWERS:

Does the Green Roof replace the waterproofing membrane?

A Green Roof system does not replace the waterproofing membrane. The entire system is placed on top of the waterproofing membrane. The choice of the type of waterproofing can be anything from bituminous membranes to PVC and liquid plastics. Additional root barriers are required if the waterproofing is not root protected. An asphalt shingle waterproofing is not an option. Green Roofs cannot be installed directly on shingles.

Does the Green Roof installer also do the waterproofing?

In general the Roofing Contractor installs the waterproofing system and a specially trained Landscape Contractor installs the Green Roof System. The success of a Green Roof depends on good cooperation between these two disciplines.

How do you deal with the warranty issue because the roof contractor will blame the Green Roof installer and the other way?

The different lines of responsibility should be included in the contract at the outset. In practice the landscaper/Green Roof installer will often be working as a subcontractor for the roof contractor. The installation of the Green Roof system (from the root barrier at the bottom to the plants at the top) is the responsibility of the landscape contractor. Ideally, both the roofer and the landscape contractor offer a warranty on the functionality of their respective systems. At the planning stage, in order to prevent future problems, the necessary alterations are designed into the building in preparation for the Green Roof. The parties involved in this can include (but not necessarily be limited to) the building architect/designer, the engineer, the roofing contractor, the landscape architect/designer and the landscaper/green roof installer.
After installing the waterproofing, it should be checked for leaks. This could be a visual inspection, however, the preferred method is a 24 hr flood test. Having passed this test, the landscape contractor can begin the green roof installation. Green Roof systems should be backed up by a warranty to ensure long term benefits of the green roof installation.
The ZinCo Green Roof system is backed by a 5 year minimum 'fit for function' warranty.

Can you install a Green Roof over an existing roof?

Yes, you can provide a Green Roof on a existing roof that has a waterproofing membrane. It is, however, advisable to install a new layer of single ply waterproofing on top of the existing one. A Green Roof can last for a long time and you don't want remove the Green Roof to replace the old waterproofing.

How long do Green Roofs last?

A properly designed, installed and maintained Green Roof should not have an upper limit to its life expectancy. There are many ZinCo Green Roofs in Europe that are still going strong 30 years after the initial installation. The plant communities on a well designed, installed and maintained Green Roof are self perpetuating. In practice it is the waterproofing membrane that is the limiting factor.

Can you install Green Roofs on sloped roofs?

ZinCo has developed two Green Roof systems specifically for sloped roofs. The Floratec FS75 system can be used on slopes up to 20 degrees and the large plastic modules of the Georaster system can be used up to 35 degrees. Both systems have drain layers specifically designed to hold the growing medium and prevent it from slipping. Some alterations to the soffit area of the roof are required to brace and support the Green Roof system.

Can you do Green Roofs in a residential setting?

Most houses in Canada have sloped roofs and as noted above, there are two ZinCo systems designed for these applications. There is no difference between commercial and residential applications. In fact in Europe residential applications of Green Roofs is very common.