My goal was to add another layer of insulation onto the roof that would help to keep our roof deck dry. And lo and behold, I found insulated roof pavers (or panels) on the reuse market.
These two by four foot, tongue and groove panels are two inches thick: 1 5/8 inches of XPS insulation, covered with a 3/8 inch latex modified concrete. They give me an additional R-value (insulation value) of eight, and only add 4.5 lb per square foot to the weight, which kept me well within the load capacity range of our roof.
I love that the panels combine the function of insulation and roof ballast in one product. Plus they provide a comfortable walking surface, and protect the roofing system from the elements, such as extreme temperature fluctuations, hail, UV radiation, etc. But they must be installed over a drainage layer. If not, they may sit in water for extended periods and may turn into a very heavy sponge. That would not only negate their insulation value, but also add a lot of weight.
After we hoisted the insulated roof pavers onto the roof, I set up a couple of mason lines and squared them. Those were my guides for laying down the panels, and in the process, minimize any cutting.
The areas that receive the forthcoming solar PV modules did not receive the insulated pavers. Fitting them around the solar posts seemed too complicated. Instead these areas will receive regular XPS insulation covered with regular roof ballast.
Although we had the solar posts installed, we were not moving ahead with the solar array right away. There were a few other items that we needed to address first, namely the drainage layer and the insulated roof pavers, which will be the subject of the next posts.
I have designed and engineered enough green roofs to understand that materials on top of a roofing system should be separated by an appropriate drainage layer. In our case, we opted for a 1/4 inch dimple mat, with a geotextile on top. It is the very same material we used for the vent strip installation.
The 1/4 inch mat gave us enough flow rate to effectively drain precipitation off the roof and prevent the forthcoming insulated pavers from sitting in water. The geotextile that is attached to the top of the dimples helps to keep debris out of the 1/4 gap to maintain the needed flow rate.
The material selection came naturally: While scouting our regional reuse stores, I came across several rolls of the dimple mat, which must have been surplus from another project. I was short a couple of rolls, but was able to purchase those new to have enough square footage for our roof.
The mat came in rolls measuring 4 feet by 50 feet and should be installed perpendicular to the roof slope, starting at the bottom of the roof, similar to the base sheet and torch down membrane. For logistical reasons, we started laying down the mat at the top, but made sure that all the overlaps were pointing downstream.
We very carefully swept the roof first to make sure there was no debris under the drainage mat. While rolling it out, we cut small openings into the mat to fit it over the solar posts. We also made sure to weigh it down with pavers to prevent it from blowing off.
Along the parapet, we extended the drainage mat over the cant strips, similar to the base sheet and torch down installation. We can always cut the drainage mat back later, if needed, but we can’t add to it.
I get a kick out of reusing and repurposing salvaged materials, whether it is in the house, the yard, or in this case, our parkway landscape.
We have two gates to our property: the main gate leading up to the front door and the side gate leading into the side yard. It made sense to provide a path crossing through the parkway landscape at each gate.
We already had a path crossing at the main gate, although it needed some additional work. More about that later. But there was no formal path crossing at the side gate. While laying out and installing the parkway knee fence, I made sure to provide a gap for a path to connect to the street.
A material question
No, I will not use poured concrete. Boring! It can be the default pavement choice around the country all day long. That doesn’t mean I have to like it or bow to it. And on top of that, it’s not even that practical. It tends to crack over time. And repairing it always looks like – well – it has been repaired.
I had some beautiful salvaged graystone and clay pavers in my yard that were perfect to craft a path crossing through the parkway. I knew I could repurpose the graystone into a curb flanking the path left and right. The clay pavers are modular, which makes for a much higher quality pavement if installed correctly. It doesn’t crack, because it has cracks already built into it – the joints between each paver. And it is easy to repair, because – well – it’s modular.
Building it up from the base
I put a decent eight inch base down using recycled aggregate and made sure to compact it thoroughly. Integrated into the base were two two-inch PVC pipes. They will hydraulically connect the parkway rain garden to the east and west of the path.
I also had the city water vault and shut-off valve in the path of the parkway path. (Probably not perfect, perhaps even painful, to pitch this many p’s in one phrase. But once I plunge into a pattern of packing p’s I am past picky.)
I had to align the pavement elevation with the valve and vault. The elevation of the valve was set and I couldn’t change it. But I could adjust the elevation of the vault base and I did, so that it matched the path slope determined by the valve.
With the pavement elevations set, I put a concrete base down and set the curb using my salvaged graystone. Most paver installations need a structural constraint around the edges, or otherwise the pavers start migrating over time. That is particularly true if they are adjacent to a downward slope like my planned rain garden – even if it’s only a four or six inch drop. So the curb on a concrete base was a must.
After the concrete had cured for a day, I could bring the gravel base up to the right elevation and start to screed the sand bed (setting layer) for the pavers. Then I set the clay pavers right into the sand bed. There was some fitting involved along the edges and around the vault. To fill the smaller gaps I switched from clay pavers to graystone scraps.
To finish the job, I needed to fill in the paver joints with sand, make sure the pavers sat firmly in the sand bed, and assure the paver surface was even. The sand can be broomed and washed into the joints. To set the pavers firmly I used a two by four and a hammer and whacked the pavers into the sand bed. That process also allowed me to get to an even surface.
We set the knee fence posts along the street a good 12 inches back from the curb. That gave us enough room to install an paver strip that should measure at least 18 inches from the front of the curb to the face of the fence.
This would be enough room for passengers in parked cars on the street to open the door and step out. The fence in turn would prevent passengers from stepping into the parkway landscape or their car doors from swinging into the parkway vegetation.
We will transform the parkway into a rain garden. That means the elevation of the rain garden will be around six inches lower than the current elevation. To help with the transition between the two different elevations, we added a small hard edge along the east and west end, which serves as a curb for the rain garden.
A lot of things can go wrong in an urban environment. Someone could end up driving into the parkway. There is little I can do about that. But I can prepare for other things. For instance, what if someone drives onto the paver strip?
To prepare for this eventuality, we put down a solid six inch aggregate base with recycled material. On top went a setting layer of coarse sand into which I laid the pavers.
The pavers themselves need to have a certain mass to be cut out for the job. Some of the salvaged limestone pieces that I had stored in the yard were perfect for the job. At 12 inches wide and four inches thick they had the weight and soundness I was looking for.
I wouldn’t be surprised if the paver strip ends up being better built than the adjacent road itself.
Let me try something very different today: This is my attempt to write up a recipe using only leftovers.
We have a very nice and useful collection of cooking pots and cast iron pans, but they’ve begun to clutter up our kitchen. That sparked the idea for a recipe with left-overs. Here we go:
Ingredients:
Salvaged old growth stud scraps (preferably close to a 100 years old)
Leftover 5/8 inch poplar dowels
Leftover wood glue
Leftover VOC free lacquer
Preparation:
Carefully place the old growth scraps on prepared saw horses and clean them (some people refer to this process in a rather rough and tumble way as de-nailing).
To assure the most delicious surface texture, I recommend rubbing the old growth studs with 60 grit sandpaper first, followed by 120 grit. For the gourmets among us, keep rubbing with 200 grit.
Core the cleaned and prepared old growth scraps at the desired intervals. For the best possible presentation, it is recommended to match the core size exactly with the size of the leftover dowels.
Next, chop the leftover dowels into the appropriate lengths. Shorter pieces feed into the old growth scrap connection. Longer pieces stretch across.
Carefully marinate the short pieces in wood glue and immediately insert into the prepared old growth scraps. Only marinate the ends of the long pieces and immediately place into the prepared cores.
Carefully clamp the ingredients and let rest for at least 12 hours.
Remove clamps and glaze with two coats of the leftover VOC lacquer. It is recommended to let each coat bake at room temperature for about four hours.
Et voilà, a wonderful pot rack entirely made from leftovers!
