Alternative Waterproof Membranes for Living Roofs — 9 Comments

  1. I have been looking at different pondliners. I find epdn very expensive and is now considering a material called flexiliner. Anybody who has experience with flexiliner?

  2. In the old days shipbuilders would use pine pitch to chink the gaps between the slats in boats. I haven’t worked with pitch yet myself, but I wonder if that could do the job? Someday in the future when I actually get the chance to build my own house, hopefully I’ll be able to experiment with that.

    • It could work. Just realize water will find a way through the tiniest cracks. And over time most every waterproof sealant will dry and crack. This leads to constant maintenance headaches in rainy climates. You can’t ignore it or your roof structure will gradually rot and fail, and all that heavy soil would collapse.

  3. We have used pondliner – which is PVC based but with a tear resistant cloth. It is weldable. On top of that is a recycled wool bases carpet underlay and then coir geotextile 600gm psm.. Locally sourced sods are 80mm thick. All our roofs are at 26 degrees.

  4. Pingback:Energy Tough Love Blog » Living Roofs Are Possible Even On Smaller Roofs – Try it on an outbuilding

  5. Owen, what is your position on using recycled vinyl billboards as an underlayment that is then covered with cob – in a non-living roof situation? I live in a humid area with lots of rain fall (+60″ year) and ample signs. I was planning on using same as a vapor barrier for the earthen floors, walls and roof but am now apprehensive based on your comment.

    • You don’t need moisture barriers in walls. In fact, they can trap moisture in the wall and cause problems. Far better to build wider roof overhangs to protect walls.

      For floors, it’s best to raise the building site so water drains away from the structure. I use road base for this and drive a truck over it back and forth. Then build on rubble trench foundations.

      For the roof, vinyl is an option. I don’t trust it after watching the movie Blue Vinyl. This stuff is really dangerous, and yet it’s everywhere in plumbing and so on. Our culture is sick. Who would willingly poison themselves and their environment and not really care?

      But there may very well be unhealthy side affects from truckers tarps and swimming pool covers. Any synthetic material could cause problems. I was thinking of using recycled materials in good condition where most of the nasty fumes have already offgassed, but I can’t say for sure these things are totally safe.

      The simplest solution seems to be layers of 6 mil plastic sheeting that is separated with scrap cardboard. Work as carefully as possible to avoid punctures. (Note: this plastic lasts a very long time if not exposed to sunlight.)

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