While We Wait, Prepping The Main Roof...

The Main Roof

While we wait for the sedums for the kitchen roof to be "hardened off" at the nursery and picked up, its time to get started on the main roof.

The main roof is also a "flat roof" : an area of about 600 sq ft clear (approx 60 m2).  It was designed from the outset to hold a green living roof and / or solar panels, up to a certain (weight) point.  

Through the design process, repetitious calculations and Municipal "discussions" we worked toward a design that has 4" (100mm) of growing medium on the main roof, and 6" (150mm) of growing medium on the upper roof (of the 3rd storey walkout).  Both these areas would be topped with the XEROFlor XF301 XF301 pre-vegetated Sedum mat. More about it later.

Our PV solar panel array consists of 21 panels taking up about half the main roof.  Efficiently distributed for a PV array, but leaving difficult spaces for a living green roof. 

As with the kitchen roof, the first layer to be added is the "protection" layer. Strongly recommended by the roof membrane manufacturer if we wish to keep our 15 year warranty intact. 

Strongly recommended by me even if you don't plan to drop scissors, drills and other sharp objects..... I'm not usually a "belts, braces and both hands" person, but when it come to roofs and other things that are excessively difficult to fix, I'm quite happy to slather on thick protection.

As before, we used the DUROLAST WalkTRAK III product, and cut it to fit our geometry.  The yellow overlap edges are irrelevant for us - its just some pieces of WalkTRAK we found (recovered) from the builders storage, leftover from another roofing job.

The large open area north of the "walk-out".

The fitting of the material was not a big deal, although it does take some time and a bit of cutting.  All my fiddling took a day to do both of the upper roofs.  I elected to do  all my cutting on the wooden deck. It was a bit safer. all things considered.

The WalkTRAK III material comes in 5' by 5'  (1.5m by 1.5m) and 5' by 2.5' (1.5m by 0.75m) sizes.  You just need to conserve your big pieces for the large open areas and be prepared to use the off-curs and scraps everywhere else. We probably have a bit more overlap in some places than is strictly needed, especially in the high traffic zones where we would be walking long term on" Walking Panels".  More about Walking Panels in tomorrows blog.

And after all of that we still have some scrap left over for a variety of "projects" in the coming decades.

If your roof manufacturers warranty is not an issue, then you should consider other possibly cheaper protection layer material.  For a while I looked at the thickish mats that machine operators stand on in a machine shop. So long as it is continuous, and sufficiently thick to stop sharp chisels, nails, scissors and spinning drill bits from penetration, then you are likely good to go. The "Uline" catalogue (www.uline.ca) has a good selection of contenders.

Wot Doesn't Kill You Makes You Stronger

We Have A Leak in the Roof

Personally, I think we've had a leak on one part of the flat roof from day 1 when the house was built only 3 years ago. It's just that the water has only been sufficiently deep twice in that time to cause a leak to flow.

Flat roofs are drained by scuppers.  Under most (shallow) circumstances the water on our roof flows away very quickly.  

However, during the December 2012 Toronto Ice Storm we accumulated about 4 inches of ice and several inches of water, when it all started to melt in mid-January.  The scuppers are only 3" high so they were all frozen solidly until the melt started.  

Water depth - well on the high side of 4 inches. And we had a leak from the roof of the walk-out.

Several kettles of boiling water and half a bag of rock salt saved that day.  (Easy when you have a water softener in the basement.)  The roofing contractor (who did the original installation) had a quick look a few weeks later under dry conditions and said there was not a problem, He suggested I caulk a couple of places. Said he did not like scuppers as they usually cause problems.

Roll forward two years to "last week (April 2015)" when the roofing contractor was here to deliver some roof protection material (WalkTRAK III).  I asked him to look at it again.  After some mechanical probing, he pronounced it healthy.  I then caulked a couple of places as per his suggestion and a couple of other places I thought were suspect.

Now the big underlying issue (to me) is that the City requires a document pronouncing the roof to be not leaking, or that it is monitored (in real time) for leaks.  The easiest and cheapest way is a (48 hour) Flood Test, to a sustained depth of 4".  Real time monitoring  and other acceptable testing techniques take time, money and electrical machinery that I have neither the time, nor wallet nor inclination to acquire and install. Too much ongoing management.

Most of our roofs (we have four separate segments) were flooded for many days in January 2013, much deeper than 4", so I consider them "passed".  But the roof of the walk-out needed (re)testing properly, having failed drippingly in January 2013.

So yesterday morning I blocked the outlet of the particular scupper and started adding water via the roof top hose.  It was good at "just covered" and at 1 inch water depth.  At 2 inches water started to flow quite obviously down the interior wall.  O me miserum.

Quickly pulled the plug and turned up the heat. Called the contractor.

Its not quite that bad, but ... it leaks!

The roofing contractors fixit guy is coming over on Wednesday and we will fix this matter once and for all !

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For the record ....  and I quote in part ...

TORONTO MUNICIPAL CODE CHAPTER 492, GREEN ROOFS, 

ARTICLE IV Toronto Green Roof Construction Standard

§ 492-9. Toronto Green Roof Construction Standard: mandatory provisions.

H. Waterproofing. 

(2) Immediately prior to installation of the green roof, the applicant shall cause to be conducted one of the following leakage testing protocols: 

      (a) Flood test; 

      (b) Electric field vector mapping; 

      (c) Impedance test; 

      (d) Infrared (IR) thermal imaging; 

      (e) Low voltage testing; 

      (f) High voltage testing; 

      (g) Moisture sensors; 

and a report documenting a successful test, signed by an architect or engineer, shall be provided to the Chief Building Official 

Preparing the Kitchen Roof - Layers Upon Layers

Preparing the Kitchen Roof - Layers Upon Layers

A little water has flowed under the bridge of time, and now I must finish the documentation. I left the kitchen roof at the rivets and railings stage.  

Day 3

Finished off the railings on the kitchen roof today. It transpires that it is easier to terminate or join the railing segments mid-span rather than in the corners. Mainly because its easier to assemble up on the roof with much less drilling, screwing and riveting. The Xeroflor railing system come with a neat little u-shaped brackets that you and use with self-tapping screws to make joins very quickly on straight pieces. These joiners don't work in corners and you then have to connive a stable connection. Which takes time. Inordinately...

The next layer is .......

Layer 4  - Drainage Layer

This is a coarse looped material known as XF 108H at Xeroflor.  The XF 108H drain mat is a three-dimensional, lightweight, and flexible composite material made up of a drainage core of looped polyamide filaments bonded to a specially perforated, nonwoven filter fabric, to quote from the product doc.  Its quite stiff but has "bounce back body". It crushes when you stand on it but then sprigs back to an open 3/4 inch thickness.

I put one layer everywhere inside the railing, and  a second layer along the downstream edge to provide a drainage pathway underneath the railing.



This stuff comes in 60 m long rolls and is quite light.  One person can carry a whole roll.  Cuts with regular scissors.  It lays down quickly. The black loopy side goes "down" with the fabric filter cloth on the "up" side.

Here is the drainage layer installed across the kitchen roof.

The next layer is .....

Layer 5: Water Storage

On of the problems with roof gardens is moisture - as in insufficient.  So we put in "growing medium" (in lieu of soil) which can hold some moisture, and fleecy felted layers of "water storage.  Otherwise we would be watering almost continuously in the bright sunny and very hot roof-top environments. 

We used a thick fleecy material called "XF157  Water Retention and Filtre Fleece.  It is about 1/4 inch thick and comes in 20 m by 1.3 m rolls and can be cut with kitchen scissors.

It looks like recycled cotton / felt.

I ended up putting two layers on, with seams at 90 degrees to cut down the risk of growing medium flowing ( or is it subsiding) away.   I spent some time dovetailing the corners of the fleece to ensure that all the growing medium (next layer) is retained up on the roof. 

The timber is just to hold the fleece down "overnight" in the absence of the next two layers.

End of Day 3. Now we need to find some sedums and growing medium.

"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.

Spring Has Sprung, Finally......

Spring Has Sprung! 

(last week for a few days, maybe....)

Spring has sprung, the grass is riz, I wonder where dem boidies iz?

After a long and quiet winter staring at my Building Permit I have finally ordered some stuff and we are moving ahead yet again.  My driveway and garage now resemble Home Depot on a bad day.

The delivery #1 was on a rainy day so the absorbent layers were stuffed into the garage.  The family car is "out" for the duration.

Growing medium does not look particularly light-weight at all.

 The "drainage layer is actually very light so won't be too big a deal to install it.

This afternoon we start the serious work on the railing and root barrier for the kitchen roof.  It is the most accessible - "most" being a relative term.  

We're now on a bit of a timeline as the sedum mats are arriving on the Friday of the May long weekend - only 3 weeks away. 

I did have a (n e-mail) chat with my local City building inspector to learn that they will be delighted to look at it  - when its finished.

Full steam ahead and dodge the torpedoes!

Will keep you posted.

BTW, I had the pleasure of helping out at Don Mills CI on their Earth Day celebration this week  Spoke to some slides for half an hour about Cool Roofs : PV Solar Systems and Green Roofs. It went well and they were a very receptive audience. About 250 teenagers and a few staff.