It provides drainage but are used when water retention is required. You install them in the opposite direction of the other Drain products with the dimples facing down so it stores water. There is perforation between the dimple to allow the overflow to run off. Both sides have fabric, the bottom fabric allows the dimples to spread during installation and the top to keep debris from clogging the dimple and perforation. ½” has water retention of 0.06 gal/ft², the compressive strength of 15,000 psf and close to a ½” inch thickness. 1” has water retention of 0.11 gal/ft², the compressive strength of 9,000 psf, and a 1” inch thickness.
Ram Protection Course
Make sure you choose a protection course that is compatible.
Heavy-duty protection course of polyester reinforced, SBS modified bitumen membrane with sanded surfaces @ 3mm. Medium duty protection course of polyester reinforced, SBS modified bitumen membrane with sanded surfaces @ 2.2 mm. There are other SBS polymer-modified, polyester reinforced modified bitumen membrane with a ceramic granule surface protection. The granular surface creates a UV stable protection course and is an extreme duty protection course.
On larger plaza decks that will receive several other trades working on the membrane before the overburden installation you need to make sure you have the correct protection course. One with white granular is always nice because it is an easy visual if damaged and is 4 mm thick compared to 2.2 and 3mm. Thicker is better when it comes to protection.
Install root barrier into a horizontal plane away from waterproofing, prevent root damage to the waterproofing membrane and prevent root intrusion into Green Roof and planters application.
Devils in the details. These are where most buildings tend to leak. Do not go the cheap and quick way, will cost you in the end. Manufactures will supply the architectural details and spec guidelines. These should always be followed