Green but not living...

Poor Mans Green Roof!

There was a break of a few days between the hoisting of the growing medium and the arrival of the main load of sedums.

Winds were forecast.  As I didn't particularly wish to turn WIllowdale into a Saharan dust storm I applied one unit of green roof.

Green:  Ex Home Depot.

Ballast - courtesy of neighbouring building site  - on short term loan....

Hoisting the GM

Hoisting the Growing Medium (GM)

Following the installation of the edge railing, the next layer to be installed was the drainage layer. It was the same highly porous open weave material as was use don the kitchen roof.  It cuts with scissors and is laid with the grey filter fabric side facing up.

The next layer was a double layer of the water storage cloth.  While the open areas are pretty straight forward, the multitudinous corners took a lot of dovetailing and other finessing to ensure that there were no pathways for the GM to sluice through.

Wide spaces are quick and easy : two layers set perpendicular to each other.

Corners take a lot more finessing to ensure double coverage.

Corners are quite time consuming and fiddly.

And then the BIG DAY comes ... to hoist the growing medium.

It's a big day because this was the first of only two tasks that I could not do myself.  I needed heavy machinery and operators.  The GM was delivered in 1 cubic yard totes, each weighing about a ton.  In hindsight we were lucky to not be using the SOPREMA GM which is delivered in 4 yard totes - destined for large areas like condo and factory roof tops.

Growing Medium is NOT soil.!! No one says what is really in GM, but Xeroflor describe it as a proprietary mixture of lightweight, mineral based materials; including porous aggregate and organic matter derived from composted plant materials.  It is more mineral than organic, so it won't break down and disappear to quickly like soil would.  Our GM had a noticeable red hue to it from crushed brick material.

The sizing of the GM was in the grit to fine gravel range. All sub- 3/8".  Very little in the clay-silt-fine sand sizings.  Not all all well sorted.

Here is a post -hoist photo of rain-washed growing medium.  It has a distinctly red hue from the crushed brick component.

In our installation we planned to use a 4" (100 mm) layer on the main roof, amongst the solar panels, with a 6" (150 mm) layer of GM being used on the roof of the 3rd storey walkout.  

Why 1 ?? Because that's all we could reasonably hold within the structural limitations of the roofs.

Why 2?? Because a thickness of GM would provide additional water storage to reduce the frequency of watering.

Why 3?? Because we might elect to broadcast some native plant seed next spring, and they grow better (more reliably) with some GM into which they can stretch their roots.

Then the issue is how to move about 6 cubic yards of this stuff up 25 (8 m) or 35 ft (11.5 m).  My back was not that strong.  However Lino's loader was. 

Our neighbours were building a home and friend Lino,  the framer, had a "zoom boom" that was rated for 1 ton up 42 feet.

Lino's "zoom boom" without which we would have been skunked, and substantially poorer.

Lino is always good for a challenge, and came over in the evenings to help out.. We put totes destined for the highest roof 35 ft (11.1 m) onto a pallet and then hoisted it over the edge of the roof.  The totes for the main roof, at its lower elevation of (only) 25 fee,t were hoisted by their own straps.

The active end of Lino's loader, from the top, down about 30 feet..

I then cut away the side or bottom of the tote so its contents fell gently into a temporary hopper.  From there we shoveled it out around the roof with snow shovels, raking it into place but not compacting it particularly.

GM spilling gently onto the 3rd storey walkout roof.

Temporary hopper that holds about a yard of GM . We then shovelled it around the roof with grain / snow shovels

Getting started.

Vital tools

This funny looking jut-out is to provide space for the adjacent electrical control box to be opened.  It has the circuit breakers for the individual chains of solar panels and might be needed for SP maintenance: assuming you can still open it.

.

Almost there.

Finished, ready for the living layer.
The GM is finished off about an inch below the top of the edging, by design.

Raked, but not compacted.

What does hoisting cost?.  Depends!.  Buddy rates are negotiable.

Commercial rates for a crane truck that could lift 1 ton about 40 feet "up" and 10 feet traversely ("over") run about $165 per hour (Ontario, 2014) : four hour minimum, including all travel time.

Our dilemma was that we could not hoist all 6 yards in the same session as we did not have places to temporarily stage them within reach of a regular crane truck. In the end we did it in 3 separate sessions based on 3 different staging areas.

 A substantially bigger machine would have been needed to increase the dimension of the traverse distance covered.   We needed to hoist 1 ton  30 feet horizontally at 40 feet vertically.  A bit of a challenge $$$$$$!

Friend Lino and his marvellous lifter fitted the bill wonderfully.

Railings

Edge Railings

The edge railings are based on "L" shaped aluminium extrusions.  They are used on the perimeter of the installation to contain it, provide a nice edging, and prevent  the growing medium from sloughing away or resting directly in the structural elements of the home ; walls, parapets.

Edge Railing

The material we used is the Xeroflor XF510 "XeroEdge" product.  There are likely others in the market place.  The slots at the base of the vertical plane are for drainage.  It is available in a range of heights : we used the 4", 7" and 9" varieties within our installation.  This material comes any length you want, so long as it is 10 feet. However, if you are careful there will be very little wastage or scrap left over. 

It comes with neat little U-shaped joiners that slide up underneath the top lip of the channel and are simply and quickly attached with PK or self tapping screws (supplied in abundance).  The trick is the make sure that your joins are always in the middle of long runs, and never in the corners. In practice I ended up attaching the joiners to the vertical face first and then put the vertical screws in the top second. Whole lot easier to hold / faster to complete.

A word to the cautious: be careful to vacuum up all your aluminium shards created by the self-tapping screws lest that puncture your root barrier, protective layer and roof membrane.

Our main roof installation was a bit complicated by the highly irregular shape of the solar panels plus the walking pads.  There are a (large) number of short elements plus some longer runs.

I tried (initially) working with one large DWG.  That didn't work out at all. I ended up (re)measuring / cutting / installing each edging section in succession : 10 feet at a time.

First you measure, being careful to identify the "inside" corners where a V of material will need to be removed, and the "outside" corners where a simple cut suffices. In fact, measuring twice helps. I worked to 1/4" units and was not caught out too badly.  Here are a couple of typical sketches used.

Working DWG

Another Working DWG

The "outside" corners are straight forward in the you just cut through the horizontal plane and then bend the vertical plane around the Z axis.  I used a  40 tooth "aluminium" blade in my 7" size circular saw to do all the cutting.  Then hand filed all the sharp / arris edges smooth. Then bent it by hand.

The "inside " corners take more work as you need to remove a 90 degree V shape (100 deg is better) form all the horizontal planes before you cab bend it. Although this material can be easily cut with "tin snips" you will need both left handed and right handed ones to  most easily / quickly / neatly deal with both sides of some of the cutting.

An "inside" corner marked for cutting the V out of the horizontal plane

A very typical section showing, an "outside" corner, then an "inside" corner, then another "outside" corner. bent, ready for installation 

Another example of one section. all bent into shape ready for installation

Yet another example of one 10 foot long section, all bent into shape ready for installation.

We used over 30 sections of railing.in our installation.  Only two of them were used "straight".  None of the others were the same, or even slightly resembled another.

The fabrication of the edge railings was very tome consuming.  With all the measuring in the roof, then marking in the garage, then remeasuring on the roof, then cutting, snipping and filing in the garage  took an inordinate amount of time.  About an hour per length, at least, and two hours for the complex ones.

Here is a selection of photos of the actual installations.  The black layer is the root barrier.

At a couple of places, the living roof is installed underneath the cantilevered solar panels.

The vents from the house sewers received their own edges.

This shows the roof of the 3rd storey walkout.  The edge railing is 9" high and shows shaping around the drainage outlet on the LHS to accommodate rock salt for winter melting. Half a bag of rock salt in the early winter will keep the drainage way open through all sorts of snow and ice.

Walking Pads

What Is A "Walking Pad" 

and 

Why Do I Need Them?

Our roof is not homogeneous.  We are blessed with a small deck, a cluteratti of 21 PV solar  panels and "zero to a few" feet of snow every winter.

The logic of walking pads works this way. 

• In order to maximize your PV solar generation (= MicroFIT revenue$) you need to keep the solar panels clear of all impediments like leaves, pollen and snow / ice. 

• To keep the panels clean, you need good safe access so your can sweep the snow away, or pollen as the season dictates..  

How often?  It varies with snow fall.  Last winter (2014-2015) was 16 sweeping events.  The prior winter it was swept 14 times.  It is my experience that the sun will melt about 2 mm (1/8 inch) of snow fairly easily and quickly, but if you have more than that depth and you need to sweep, or you'll miss out on a days solar production. I don't sweep frosts, but will sweep pretty much any and all snow falls. [ I don't worry about clear ice, especially if it's thin. Does not seem to inhibit PV production. I daresay, its all about direct sunlight.]

• You can't walk on sedums, and certainly not repetitiously. This is a big concern for the living roof.

Even if there is a thick mantle of snow insulating the sedums.

Therefore, I have created a demon called a "walking panel' to provide me with a safe, sturdy place upon which I can walk, and sweep snow, while not damaging our precious sedums.

A walking panel is basically a box 12" (0.3m) wide by 3-4 feet (0.8 - 1.2m) long, about 7"  high (17.5cm) (edge railing height, by definition), with a  durable top - concrete wall cladding in our case. 

My initial thought was to make plywood boxes.  But, at $70 per sheet for good, water protected Crezon wood, the cost would have been prohibitive. Especially as I have a building site next door with a small forest of scrap timber that is also PT (pressure treated) and where "the price was right". I also wanted a more durable topping surface than plywood would provide.

In the end, my walking pads were framed with (mostly) scrap PT wood, capped with crezon panels that were left over from another project (the "Shrubs In Tubs" blog entry) and topped with offcuts of the same concrete panels that were used for the rain shield for the house.

Last winter I kept track (poor pun) of where I walked every time I swept the solar panels.

As the winter progressed I refined this pathway to its minimum, while still providing sufficient coverage for a clean sweep.  
That drawing provided the locations for the walking pads.

The Greening of the Kitchen Roof, Finally

Kitchen Roof Topping Off

After about a year of eager anticipation, the big day had arrived when I could finally, put the living / green layer onto the kitchen roof.  

Rain, a couple of days prior, had wetted down the water storage layers so I did not feel the need to wet them especially.  

The first layer to go on today is the "growing medium". It will provide basis for rooting by the sedums, eventually, plus a modest amount of water storage.  In reality, it will keep the sun a further inch away from our kitchen, to reduce our summer cooling loads.

"Growing Medium"  a mineral based manufactured material, never to be confused with soil / triple mix and the usual bunch of horticultural soils.  The difference is that growing medium is predominantly mineral or aggregate based with only a small portion of organics. It does not break down as easily as soil, which has a much higher organic proportion.  If you were to use "soil" on your roof, then it would eventually breakdown, lose its structure and flow away like mud. Ans soil can get very heavy when its is wet : it can have a very high "field capacity".

The downside of using growing medium is that it does not easily provide nutrients to the plants. so we will need to add these regularly, in perpetuity.

In our installation we used XeroTERR growing medium from the XERO Flor company.  

"XeroTerr" is described officially as a  "Lightweight aggregate growing medium mixed specifically for use within Xero Flor mats and green roof system build-ups. (It is) A proprietary mixture of lightweight, mineral based materials; including porous aggregate and organic matter derived from composted plant materials."  Our batch had a noticeable portion of crushed brick in it.

From the labels on the 1 yard totes, this material was manufactured locally in Ontario.   

A bucket of growing medium

The growing medium is spread in a layer: raked but not compacted.  On this roof the layer was about an inch thick (25mm).  That is as much as we could put onto the roof and stay within the structural strength limitations.

Two Minimats ready to be placed

I ended using a kneeling board just to prevent compaction of the growing medium. You basically lay down the Minimats and jam them against each other.

Shaping of mats to fit "geometry" is really easy, requiring only a sharp cutter, a board,  and some elbow grease. 

End of the first row, fitted to the outlet shape.

Repeat until finished.

I will add that the hardest part of the work was the lugging of the growing material around from the driveway (where it had been delivered in 1 yard sized totes) and up the ladder.

There was very little wastage or "left over" sedum minmat. One spare piece would usually be sufficient if your area calculations are good. We had both our "spare" and two half mats declared surplus to requirements. They will be used somewhere else round the garden.

I did water it quite well on the first day - until the water ran from the gutter.  Overnight the sedums "perked up" noticeably an soon poked a good inch above the railing.  A couple of warm days also helped their recovery.

This is the view from my office at the end of installation.  The sedums are a bit squished, but will (did) recover very well after a good watering and a couple of warm days.

Later Comment : We are noticing a gradual change in the look over time.  The sunny parts of the roof are becoming quite a bit redder and the taller species are beginning to poke through.   I'll post some progress pictures later on.

====================================================================

Xeroflor Canada Inc. is located at  One Yonge St., Ste 1801, Toronto, ON, Canada, M5E 1W7

Tel: 416.637.5772


General Mailbox : info@xeroflorcanada.ca

http://www.xeroflorcanada.ca