07 April 2011

Green Roof Science Fair Project

When Ella wanted to study green roofs for science fair project, I thought it was an interesting idea.  When it became necessary to build a green roof (or two), I said sure.  That was the first of my mistakes on the road to completing the green roof project - "Rainwater retention in green roof systems."

I knew I was winging it in my plans to build mock-ups of two green roofs, but I thought I had a really good idea and it was cheap.  I had a plan to build a chicken coop out of pallets later this year, so I thought I would test them out, while using them to build a couple of green roofs.

I ended up finding some free pallets and I had some various pieces of wood stashed in the garage for a future project, so I thought I was set.  Then I found out we needed four roofs, a flat green roof, a 40 degree green roof, a traditional flat roof and a 40 degree traditional roof.  The traditional roofs were the easy part - a piece of plywood on a pallet for support, and we even had a pile of shingles in the garage to put on one of them.  Working with the pallets was not what I expected.  I thought I would be able to take them apart fairly easily, but this was not the case.  I practically had to destroy the slats just to get them off the frame.  I kept slats on one side and reinforced it with some plywood.  I lined the pallets with plastic and landscape fabric to keep the soil from washing away.  I got most of this accomplished in a day, and then we got to work on other logistics, like what kind of soil, plants and how to set them up.  We ended up mounting them on our fence - it saved energy by only having to build supports on one side and we were able to adjust their angles as needed.  Once they were up, we attached gutters for rainwater collection.  We found really good soil at Lowe's - it was a lightweight, moisture-retaining mix that was similar to what we had read about in green roof literature.  We also found a variety of sedum from local nurseries and free from craigslist.  After planting those, we were ready for the science to begin.

It only rained a few times between when we built the roofs until the data was due.  Another factor we should have considered was the weather - winter was not the best time to do this.  In warmer weather, the plants would grow and spread and cover the roof, giving more accurate measurements of rainwater retention - and I probably would have built the roofs differently.  But it is done - it is over. and Ella's grade wasn't horrible, despite all of the project's flaws.

The roofs have been sitting there for the last couple of months, waiting to be dismantled.  I broke down the traditional roofs and put them on the street a while back, but I hadn't tackled the green roofs yet.  I finally got to those a little over a week ago.  I planned to plant them in our desert garden, but I thought some would look good in pots as well.  Most of our succulents that were on the porch died back in December - they weren't hardy and I forgot to bring them in on some of the colder nights.  These are hardy sedum and will do well all year long.

I pulled up the aloe that had died and I amended the soil in the desert garden with the mix I used on the green roofs to give it better drainage.  I had a lot of sedum in it when I first planted it and most of it died - I think it was too wet and didn't drain very well.  I'm hoping the soil mix I added will prevent that this time.  Most of the sedum is planted in the desert garden and I hope it thrives.  We'll have to wait and see.

For a slideshow of the Green Roof Science Fair Project, click here

No comments: