Green Roof Edge Detailing

Finding detail on the edge of a green roof and waterproofing it is something I struggled to do easily. I thought as I fitted the roof it would be good to take some photos and show everyone how mine is put together.

The roof consists of 18mm structural plywood, with carpets on top followed by the membrane. At the edge, the plywood overhangs by just over 2″ (5.5cm).

The membrane overhangs by about 6″ (15cm) over the edge, so it can wrap underneath the plywood. In the photo below, you can see I attached some 2″x1″ wood to the edge, which allows the membrane to wrap under and then up, forming a drip edge.

To create a drip edge, some 2x1 is screwed to the edge.

To create a drip edge, some 2×1 is screwed to the edge.

The photo below shows the roof before the drip edge is screwed on.

The plywood has carpet on it before the membrane to ensure no splinters get to it.

The plywood has carpet on it before the membrane to ensure no splinters get to it.

Once the membrane is folded over, it tucks up between the drip edge and the truss which the plywood overhangs. The feather edge board then pushes up into the gap and screws on to hold the membrane in place.

The membrane folds over the drip edge and up, and the feather edge board holds the membrane up.

The membrane folds over the drip edge and up, and the feather edge board holds the membrane up.

You can see the roof in the photo below with the finished drip edge. The next step will be to trim the membrane hanging from under the feather edge, add a weather board to protect the membrane from the sun, and then add a gutter to catch the water and direct it to somewhere more useful. All should be done this week.

The roof here with the drip edge installed. The membrane needs trimming, and a gutter.

The roof here with the drip edge installed. The membrane needs trimming, and a gutter.

I hope that helps anyone looking at creating a green roof. I would love to hear ideas of other designs and plans. As I develop mine more, I’ll post as much as I can to share more information.