Monday, September 8, 2008

Green roof installation begins

(for documentation purposes, I separated this post from the previous one)

This week, JIG will begin installing the green roof and our GC will begin constructing the roof deck. We are very excited about the fact that by the end of this week we'll have a green roof and a deck! You get so caught up in worrying about all the details sometimes when building a project that you forget to stop and enjoy the project once in a while. We'll...we feel this calls for a "topping off" party, which is now in the works. Who says they're just for "tall" buildings? And seeing that in about a month, the contractor's work will be done and it will be up to us (and a few very good friends) to finish out the house (which includes: installing all the plumbing fixtures, possibly the entire kitchen, the flooring and tile work, the wood trim, any lights that aren't recessed, and a few other minor details), we feel now might be a good a time as any to enjoy ourselves a bit since things are going to get very busy, very soon.

Back to the green roof... We had to scramble to get some last minute preparations taken care of before tomorrow - mainly the covering of the electrical wires out front (which can only be done by PECO) and laying down the EPDM root barrier. EPDM is a rubber-like membrane that comes in rolls and is mostly used as actual roofing membrane as it is waterproof and very durable. But it also makes a great root barrier, which is simply a barrier to keep the roots from damaging the actual roof membrane underneath. Of course, you can simply install a certain type of roof membrane that acts as both the waterproofing agent and the root barrier...but it's more expensive. Sorry if this is a bit confusing.

Anyways...the root barrier issue was a bit trickier due to the fact that it is "loose laid" (which means that it is not glued down to the roof membrane, as it not necessary in this case) and is best installed just before the green roof media is to be installed so there is no chance of damage to the membrane from folks working on it in addition to the fact that unless it is seriously weighted down, it could simply blow away. It's a very heavy membrane which means it could do a lot of damage if the wind ever happened to pick it up. And of course, on our project, these two tasks (laying the root barrier and installing the green roof) are done by separate contractors and thus prove challenging when the latter is supposed to start work first thing in Monday morning and a big storm is forecasted for the weekend, thus forcing the roofer to wait till the last minute to lay the membrane . Ugh! But everything seems to be working out okay...or so they tell me.

The reason we needed to cover the electrical wires is that JIG will be using a large mechanical lift (positioned in the street in front of the house) to get most of the material onto the roof. Covering the wires is simply a safety precaution in case anything or anyone should accidentally make contact with them.

To the best of my knowledge, the process of our green roof installation is as follows: First, the root barrier is laid down. Then they lay down a felt over the entire roof on top of the root barrier (except where the deck is going as this area gets a 1" deep hard plastic drainage, or "dimple", board - there is no media under the deck). Second comes the drainage mat (this has felt on the upside and a open plastic wire "tangle-weave" system about 1" thick on the downside) over all all the felt. They will also install the vertical metal edging that keeps the 8" wide river stone strip (at the front and rear edge) separate from the green roof area. The stone is for wind protection for the plants and for drainage. There is also a triangle conduit (or raceway) installed from the front of the roof to the back for drainage during heavy rains. Next comes the dirt. Then, in our case, due to the fact that we have a very low parapet, they will install a biodegradable wind protection mat (made from coconut husks...kind of like a burlap) which is tied down and keeps the plants roots in place until they are established. It takes about a year for the mat to completely disintegrate. Finally, they will cut about 900 small holes in the mat and plant all the sedum plugs in the holes. Talk about tedious work. All the while, the deck is being constructed (by our GC) and will be installed simultaneously with the dirt and plants (another scheduling challenge as it involves separate contractors). Timing these together is so the dirt and plants can blend nicely into the spaces between the staggered edges of the deck boards.

I am going to try to get pictures everyday this week to show all the progress. Should be a productive week!

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