Installation of planting boxes continues on my green roof

As is typical for most of our home projects, THIS one is bigger than we thought, and is taking more time than the original estimate.  We're at about the 60% mark, and the boxes and paths are looking really good.  We're pleased with the design and construction process. 

I had a "dry stream bed" planned to cut across the roof (actually for roof gutter outflow), but this may get cut back to a corrugated tube for convenience.  It's been a battle between rectangular boxes and free-form curves.  So far, the rectangles are winning outside of the railing. 

It also appears that we will run short of both lumber and planting mix.  My "be-as-exact-as-possible and then add 10% more" practice seems to have STILL been a little short, but we won't know how much short until we get that last box measured.  We attempted to do most of the boxes in a "standard" size to minimize waste, but are now down to having each box be made-to-fit. 

Now, to get it done and then planted.  The Memorial Day weekend approaches, and I suspect that we will be spending most of it planting, both the ground-level gardens and the green roof. 

We are taking pictures, and I'll post them to the blog as soon as I can.

Planting boxes being installed on our green roof

We spent the weekend building the planting boxes, getting about half of the garage roof covered. Each box is 24 to 30 inches wide, and up to 48" long. We're making them as close to a standard size as we can for our convenience, and then filling in any open space with pavers or river rock and gravel.

The box construction is from treated 1x4 pine, with the corners reinforced by small pieces of treated 2x2s. We're screwing the boards into the corner reinforcement with deck screws. For construction convenience, we are screwing the 2x2 pieces to the shorter 1x4 sides as a sub-assembly, and then making a jig from clamps and boards on a piece of plywood on sawhorses to put the sides (boards) and the sub-assemblies together. We tried to build the first couple of boxes on the driveway surface, but the driveway is not flat, and it increased the amount of bend-and-stoop we had to do. Elevating the worksurface --- and working on a flat stable surface --- made the boxes much more uniform, as well as making the task easier for our 50 year-old bodies.

Each screw goes into a pre-drilled hole to minimize splits, since we are screwing into two sides of the 2x2s. It took us a couple of hours to get a "system" worked out, but it is now going rather easily.

We lift the box to the roof surface, staple fiberglass screening to the bottom AND to the top, anchoring the top along one edge only. The box then goes into place.

The box is filled to about half-depth with perlite, and then filled the rest of the way with a commercial composted bark-based planting medium ( MetroMix 560).  We then pull the screening over the box, and staple down the remaining three sides. 

 

This week should see us getting the remainder of the boxes built and filled.  Planting will then begin.  Right now, we plan to use mostly sedums and sempervivums.  It is also very likely that we will do some trial plantings of small low-growing spring-flowering bulbs.  Our green roof installation is over an unheated garage, so the planting boxes will be exposed to cold temperatures both above and below.  I am expecting this to limit the species which will thrive under these conditions. 

 

There will be extensive planting posts as this project moves forward.  Species, varieties, sources, successes and failures.  And, of course, pictures. 

Green roof installation: drainage, railing, pavers

This is the old roof surface, pavers over EPDM membrane. The roll of material is the new drainage mat (Carlisle MiraDrain GR9200). The pavers have been on the membrane for six years. Sand had been swept into cracks.



New surface at about 50% installation on the right. Old surface on the left. We moved each paver at least 3X as we lifted the pavers and installed the drainage mat.



This is the reverse side of the drainage mat (Carlisle GR9200). The "cups" are about 1/4 inch deep. The cups are installed down, with the plastic against the EPDM membrane.



Close-up, reverse side of the drainage fabric, showing the cups.



Close-up of the drainage mat (Carlisle GR9200). Note that the woven fabric is see-through, and that the cups are now right-side up.


Roof surface 100% covered with drainage mat (Carlisle GR9200). Note the stack of pavers at the far corner.



Railing being installed. The railing had been on the original installation. We removed it, sand-blasted it, and had it powder-coated. Hand-painting the railing every three years with Rust-Oleum gets old quickly. Note the stacks of pavers at the rear of the roof.



First circle (ca. 9 ft) of pavers re-installed. There is a second circle to the right and to the rear of this one. We also fitted a quarter-circle in the near left corner. The remainder of the paver-covered surface will be in a modified running pattern.



Paver installation complete. Anything not covered by pavers will be covered by planting boxes or gravel-and-paver access paths.


More photos as the project moves ahead. We've started building the planting boxes, but no pictures yet.

The pavers are installed on our green roof

It took a long hard weekend, but the pavers are installed. We put in two circles --- about 8 ft each --- and a quarter circle in one of the corners.

The remainder of the roof surface will be planting boxes, made from treated 1x4 lumber in a grid of about 24" x 30". Actual dimensions will be to-fit. Each box will have fiberglass window-screen on the bottom to retain the planting mix, and window -screen on the top to keep the planting mix in the box, rather than being blown (or splashed) around the driveway and yard. We'll cut small Xs in the top screen so that we can plant, and within a year or so, the entire surface should be covered so that the boxes and screen will no longer be visible.

The boxes start this week, weather permitting. Everything is now on-hand, except for the window-screen destined for the tops of the boxes. That should arrive today by UPS.

Actually, the planting boxes will not cover the entire roof surface. We will install access paths to the boxes using the leftover pavers and river rock. We intend to create a dry stream of river rock (over a runner-style length of EPDM) across the roof to move the rainwater from one gutter system to that of the garage. And finally, we've got a small water feature planned for the "headwaters" of the dry stream that we hope will provide a constant trickling sound in the background.

I spent part of Sunday afternoon, propagating sempervivums and more sedums. I think that there are now 12 flats of 72 cells of plants destined for the roof. More on plant selection as the boxes get planted.

Installing the railing on our green roof

The railing installation (or re-installation) is complete, except for some bracing needed near the house, at the patio door.

The re-engineered railing is now in 6 or 8 ft sections, bolted together at the posts with stainless steel bolts. The original railing was sand-blasted, cut into sections for convenience, and powder-coated. We were without railing for almost a year --- we did an addition last year, and needed to remove the railing to facilitate the addition project. It looks soooo different, now that the railing is back in place.

The railing appears to be higher than before. Part of the visual difference is that my memory includes the height of the pavers, which are not yet in place. That 3" makes a big difference. The railing is also now installed ON TOP of the paver surface, rather than on the deck surface. Visually, then, I guess that the railing is actually appearing to be 6" higher than before. Half of that difference will go away once we get the pavers installed.

Which should begin this afternoon, weather permitting.

The lumber for the planting boxes is in the driveway. The perlite and MetroMix are being delivered today. Almost ready!

We are taking digital photos of each stage. Once I get some time to figure out the Blogger photo application, I'll post them.

Our green roof project --- turning a flat garage roof into a roof garden

Before you start with the new, you must deal with the old:

This project actually started 9 years ago, when we bought our house. The house has an attached garage --- with a flat roof. When we bought the house, the garage roof was sealed with asphalt, and covered in pea gravel. The first winter we were in the house, the roof leaked. Actually, there were indications (water stains) on the roof joists indicating that this was NOT a new problem, although there were no leaks during summer rains.

As a result, during the following summer, we removed the asphalt roofing, and replaced it with a fiberglass-reinforced EPDM membrane. At that point, I had the brainstorm that we should make that hot flat roof part of our living space by turning it into a Mediterranean roof garden.

We brought in a licensed engineer; reinforced the roof framing; added a jack post and a steel I-beam; had a railing fabricated to our specifications; and put down concrete pavers. We covered the roof deck with a second EPDM layer (used fabric from the roofing supplier, laid on top without adhesive, as a barrier from friction, penetration, and UV). Our original intent was to fill the roof space with containers and planters, and install drip-irrigation. Well, this worked OK, but there were a few problems with the original plan.

One, the roof was still very hot, even in our Northeastern US location. We had patio furniture on the roof, but rarely used it. The pavers retained a lot of heat, making evenings pleasant but mid-day almost unbearable.

Two, the drip irrigation worked well, but the roof deck surface did not drain especially well, nor especially completely. This resulted in long-lived puddles, algae, mosquito larvae. We had laid the pavers directly on top of the membrane (the friction barrier layer), and swept sand into the pavers as though it were a ground installation. This worked really well --- but drainage through the pavers and sand was not very fast. The pavers and sand remained moist most of the time, and we developed a great crop of moss, algae, and liverwort.

Three, the drip irrigation system (from DripWorks --- great folks, BTW) also worked well, but it did not withstand our summer sun and winter freezing very effectively.

Four, the original installation of the railing had the "feet" (the railing is supported by 4" steel posts at the corners and about every 8 lineal feet. Each post has a 6 or 8" square steel plate) UNDER the pavers. My thought at the time was that the pavers would lock the posts in place, and provide additional stability. What this really did was enable the steel plate to rust badly, since the sand/pavers rarely completely dried out.

So, we decided to lift all of the pavers; sandblast and powder-coat the railing; install a drainage fabric (a Carlisle product designed for green roof installation); re-install the railing and pavers; and then plant the entire roof surface with succulents. Our roof garden will become a green roof!

The renovation project began in earnest on 30-April-2005. Once I figure out how to post pictures to Blogger, I will post photos of the project. My intent is to describe every step of our project, from vendors, to the reasons for our choices, to plant species used in the garden.

At this point, the roof is covered by the drainage fabric, and the refurbished railing is being installed today. I've got 8 x 72 cell flats of various sedum species rooted and growing in the greenhouse. We should begin the re-install of the pavers tonight, weather permitting.

Photos soon. I promise.