Weeding is necessary on all vegetated roofs. Frequency and thoroughness is key for removing damaging weeds before they set seed. Without proper maintenance, invasive weeds can overtake a vegetated roof and pose a threat to the original design—both its aesthetics and potentially even its function. Woody plants such as maple saplings, can potentially harm the waterproofing membrane. A thin-layered system with synthetic water-retention layers tends to be less inviting for harmful weeds than systems with thick growing medium. These thin-layered systems therefore require less routine, manual weeding. Thin systems limit the variety of weeds that can take root but also naturally limit the design plant pallet—a thin layered system typically supports a variety of low growing groundcovers like sedums and mosses.
Debris removal and drain inspection
Drainage path inspection is very important. Blocked drains and pooling water can cause root rot, and plants can drown.
Document your visits
Once a properly installed extensive vegetated roof is established, its maintenance requirements are usually minimal. However, there should still be a person or team responsible for maintaining the system, performing visits three or four times a year. If the property does not have the personnel to perform this maintenance, it is recommended to hire a professional vegetated roof maintenance contractor with horticultural knowledge and ‘working at heights’ training. Each visit and recent weather conditions should be recorded. Photos are needed for future reference and any potential warranty claims.
Sasha Aguilera is a design consultant for Xeroflor Canada. Her work as a design and technical consultant, estimator, and installation inspector on projects across the country has established her as a leading vegetated roof professional. She is a Toronto-based educational speaker and presenter. Aguilera can be reached at email@example.com.