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.

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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.

"Some Assembly Required"

Installation : Day 1!

One of the tribulations of researching the construction of green roofs is that the YouTube videos are a little skimpy on some of the details.  The examples always seem pretty straight forward. And they fit into a 3 minute video clip.

So, one of the purposes of this blog is to provide a little more detail so people who wish to save the installation costs by doing-it-themselves will have a better idea of some of the pitfalls.

You may or may not be an engineer, as I am. You might have the time and the inclination. You might have the same tools in your garage. At least readers will get a better heads-up than I had.  

Or you might elect to pay a crew to do it for you. Your choice.

Commercial Declaration = Suppliers / Vendors

At the end of all the navel gazing, researching, "googling", budgeting, scheming, gleaning  and toing-and-froing I elected to buy most of the materials from the XEROFLOR company here in Toronto. Their staff are extremely helpful, particularly through the approvals phase - getting the building permit, as previously blogged

We are going to use sedum mats as our "living layer" rather than planting individual plants and waiting a season or two.  We may (later on) over-plant some of the areas with taller plants (sedges, grasses) as energy and horticultural desires permit.

We are basically using the XEROFLOR  "XF300 +XT" design, with different thicknesses of growing medium  as the roof strength permits. However, we will also be using 2 layers of fleece to provide water storage, so you might describe it at "XF300 XT + 2FL".  

Here is the link : XF300 +XT

The exception is the the sedum mats for the kitchen roof are coming from SedumMaster in Princeton, Ontario, because of a different and more colourful mix of species just outside my office window.

Growing Medium Thicknesses

This commodity is light-weight, relative to soil and has a higher mineral content.  I will put a layer 1 inch thick on the kitchen roof, 4" thick on the main roof, and 6" thick on the walk-out roof.  These numbers are all developed from the load carrying capacity of the roofs, which is based on joist dimensions, spacing and spans. [Table 6 on the Ontario Building Code was crucial part of the design process as it mandates the permutations and combination of dead / snow loads, joists and spans.]

We have 8 yards of growing medium to put into place - 2 cu ft at a time in mid-size recycling containers - up 1, 2 or 3 flights of stairs / ladders - about 120 trips all going smoothly.

Day Zero : In the beginning..

Flat roof, DUROLAST D50 TPO roof membrane, three years old.  This is the same roof all over our home, and will be "Day Zero" everywhere. The drainage is via scuppers, shown here in the middle of the left hand end.

Day One - Installation

Layer 1 - Roof Membrane Protection Layer

The first layer to be installed was the DUROLAST WalkTRAK III protection layer, as mandated by DUROLAST, the manufacturer of our DUROLAST D50 [TPO] roof membrane. This layer was needed to maintain our 15 year roof  warranty.

WalkTRAK III is a thick sheet about 3/8" thick and manufactured from scrap TPO. It is used to protect the waterproof TPO roof membrane from sharp intrusions, dropped screw drivers, chisels and boots.  It does NOT contain the usual anti-root-penetration chemicals, so a separate root barrier will be needed.

It comes in 5' by 5' sheets and can be easily cut with a box-cutter, having measured twice!!



Layer 2 - Root Barrier

The second layer is a thick polyethylene (LDPS) layer just to stop root penetration of the roof membrane.  This is made from plastic 0.5 mm thick (0.020") and is delivered in a roll.  It folds out to be 4 m wide  by 25 m long, per roll. Cuts with a pair of scissors.  The product is called XEROFLOR XF112.

The root barrier is simply cut and rolled out.  It is recommend that you have 30 cm  (1 ft) overlaps between adjacent pieces.  This not a problem because their smallest roll will cover my roof times-and-a half.

The timber in the picture is just temporary ballast so it doesn't blow away overnight.

NB: the plywood frames in the background of many of the pictures are the new houses being built next door.




The only gotcha with the root barrier material is that there is a substantial crease where the material is folded.  The crease does not pull out easily.  I have re-rolled the piece perpendicular to the crease in an overnight effort to straighten it out a bit.  Tomorrow  and a few hours of sunlight will tell.


Layer 3 - Perimeter Railing

The 3rd "layer" is a perimeter railing to contain the whole installation neatly and prevent it from collapsing sideways and flowing away down the drain.  It is an aluminium extrusion from XEROFLOR  (XF510) and comes in many heights and 10 ft lengths. We will be using the 4", 7" and 9" versions.  On the Kitchen Roof, the installation will be boxed in by the 4" high railing.

The railing material is aluminium, 1.6 mm (0.63") thick.  It can be cut with (tin) snips and a hacksaw, but have a good breakfast because cutting it by hand is grunty work.   Measure at least 3 times .....  

XEROFLOR has a corner product, but I have elected to build my own. When the sedum mats are growing well no one is going to notice who built the corners.  Not from the ground, anyway.  Beside, many of my corners (around the scuppers)  are 135 degrees, and would need to be handcrafted anyway. Besides twice, their corners look like mine, at a distance.

All the corners are braced with 3/4" aluminium straps pop riveted with the smooth side "down" towards the root barrier - penetration prevention.  I use aluminium rivets so they could be drilled out quickly and there should not be any osmotic corrosion.

As an aside, the reason for the shaping around the scuppers is simple.  Each winter I put 1/2 a bag of rock salt (water softener salt chunks) just in front of the scupper.  It prevents it from freezing past the point of blockage and causing flooding.  The shaping of the railing will keep the living components of the green roof away from the salty component.  

The first winter we were in the home was the infamous 2012/2013 Toronto Ice Storm.  We had well over 4" of ice on the roof, plus melt water.  All the 3" scuppers were frozen, blocked and flooded. We discovered one small leak on the walk-out roof, but that is another story.  Rock salt is easier than kettles of hot water or heating cables.  I checked with Durolast and they told me that the TPO membrane will not be affected by the seasonal salt.  

The fabrication of the railing takes time.  Measuring twice, then back up to the roof to remeasure up there as well.  

It also helps if you have both left and right handed snips. Thank heaven Home Depot is only a 5 minute drive away.

Thus ends Day 1. Railing is not  finished on the kitchen roof.  Have only had to drill out 5 rivets so far.  Need more measuring and prefabrication on jigs at ground level, before I lug pieces up the ladder to find them 2" too long...  The time consuming part is the succession of 135 degree corners around the scupper.