introduction to water fluxes in green roof systems 3 - ralf walker
DESCRIPTION
3. Protection mats: Water retention depending on slope and time: So far there hasn’t been a standardised testing procedure for protection mats used in green roofs. As the application varies from flat to sloped and as we wanted to get a first understanding of the potential short term water buffer related to stormwater management we developed a test procedure which would allow us the get robust results regarding the water holding capacity and a first understanding of a potential delay effect.TRANSCRIPT
Marie-Curie IAPP ‘Green Roof Systems’ Project
The Green Roof Research Conference 18-19 March 2013, Sheffield
Introduction to water fluxes in green roof systems:
3. Protection mats: Water retention depending on slope and time
Ralf Walker1, Tobias Emilsson2,
1ZinCo GmbH, [email protected], 2ZinCo GmbH, [email protected]
Introduction
So far there hasn’t been a standardised testing procedure for protection mats used in green
roofs. As the application varies from flat to sloped and as we wanted to get a first
understanding of the potential short term water buffer related to stormwater management we
developed a test procedure which would allow us the get robust results regarding the water
holding capacity and a first understanding of a potential delay effect.
Overview of Methodology
We have built two test benches where the slope can be adjusted using turnbuckles. Samples
of mats which are 500 x 500 mm in size are placed on aluminium metal sheets which have
small handles to manoeuvre them for weighing. 3 replicates were found to be enough to
achieve good results.
Figure 1: Test bench with the possibility of slope adjustment
Marie-Curie IAPP ‘Green Roof Systems’ Project
The Green Roof Research Conference 18-19 March 2013, Sheffield
Key Findings
When looking at the results, there are little buffer capacities in the short term within standard
protection mats. However other materials and compositions show greater differences. We
were able to improve the water holding of ZinCo’s mats trying out different types of material.
For an even more realistic test in future there should be drainage elements placed on top of
the mats and ballasted. Punctual compression of mats will certainly influence the amount of
water which can be retained.
Figure 2: Example of slope and time-dependent water content of protection mats
Some mats showed a capillary seam at the bottom when heavy slopes were applied. These materials
can be considered as unsuitable for sloped roof applications.
Figure 3: Capillary seam at the bottom of some mats @ 20° slope
Further Reading
https://sites.google.com/a/sheffield.ac.uk/green-roof-research/