Hints For Making A Living Green Roof
In this article were going to be looking at light weight sedum green roofs. These are the ones you often see on TV. Theyre easy to install, simple look after and dont need a lot of fuss. Sedums are by no means the only plants that like living on green roofs. However if youre a newby, or if your building hasnt been specifically designed to support a living roof, Sedum is a good choice for you.
What Is A Sedum Roof
A sedum roof is an area of a roof thats covered in a blanket of closely-knit Sedum plants. The roof will have been prepared to house a layer of substrate and then a mat or blanket of sedum. Sedum only requires a very thin layer of substrate and is relatively lightweight. So it is an excellent choice for domestic settings and super easy to install. Sedum is incredibly resilient and low maintenance and an excellent choice for a low maintenance green roof.
Green Roof Waterproof Drainage Membranes
The drainage layer of a green roof system is vitally important. It deals with rain and storm water, allowing it to drain safely away from the roof and into guttering and downpipes. By dealing with excess water, it prevents damage to the structure as well as to the plants from saturation and root damage. These green roof drainage membranes feature a stud profile that helps ensure adequate drainage.
Our PermaSEAL 8 Green Roof Membrane is suitable as a drainage membrane for extensive and intensive green roofs. Membranes like our PermaSEAL 20P Green Roof Membrane combine drainage and water storage to help ensure the long term health of your living roof.
We cover green roof drainage in more detail later on.
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Creating Your Own Green Roof
Green roofs are becoming increasingly popular in urban areas to provide green space and aesthetic diversity to a built up landscape. They provide many benefits such as improving air quality, providing a fabulous habitat for wildlife, slowing water runoff and preventing gutters from overflowing.
Small projects such as garden sheds and garage roofs can be undertaken by virtually anyone. Adding a green roof area to your home or garden does not only aesthetically improve your garden, but provides a great tool for assisting in tackling the effects of climate change.
There are three types of green roofs
1. Lightweight Extensive the simplest roof type that is very low maintenance using sedum plant.
2. Extensive the one we like! Using a mixture of sedum and wild flowers. Supports more wildlife than sedum alone.
3. Semi-intensive- more like a garden than a roof top. Using a mixture of ornamental plants, herbs and small shrubs. High maintenance and requires professional help to construct.
Root Barrier For Green Roofs
Its recommended to include a root barrier above the primary waterproofing layer to prevent any roots causing damage to the structure. These tend to be thin polyethylene plastic membranes that can simply be laid across the waterproofing layer and joined with tape.
In intensive roofs, root barriers are essential due to the potentially more wood-like and vigorous roots of the vegetation.
Photo of green roof plant roots by Kyle Ellefson on Unsplash
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Build The Tanalised Wooden Roof Frame
You will need to build a tanalised wooden frame to your existing shed roof. In this example, I have used a pent shed roof, rather than an apex, which is easier to demonstrate on. Build the frame so it provides a 3cm lip around the roof felt for the substrate and sedum blanket to be placed into. Leave the front lip off until youve fitted the waterproof membrane.
2. Attach the frame with galvanised decking screws, these are rustproof. Pre-drill pilot holes so you dont split the wood.
Myths About Living Roofs
There seem to be a lot of preconceptions about living roofs, most of which are wrong. Heres some myths you may have heard.
1. Living roofs are hard to maintain. A living roof requires very little maintenance. The grass and earth protect the waterproof layers from sun damage, so the roof lasts indefinitely. And you never have to paint it or replace tiles.
2. Living roofs will leak. As long as your waterproof membrane is laid correctly, and you have a decent root barrier, all is well. This is the driest roof Ive ever lived beneath in all my life.
3. Expensive and tricky to make. I had no money and no building experience when I built my house. The living roof is probably the most inexpensive and easiest roofing option going, especially if you use a basic pumice/gravel and blanket system.
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Building A Basic Gable Roof
Tips To Constructing A Green Roof
A roof with turf
The world of gardening provides many opportunities to express oneself by letting our imagination run wild as we embark upon an adventure with those creative style or work which is our signature. There are no set rules except for the basic or the foundation in which to build, from there we are free to let those creative juices flow.
One such garden we will be discussing is a living roof or green roof garden, these garden types have gained much popularity in urban areas because of aesthetics and other benefits that are involved. Constructing a green roof is a great way to connect with nature while helping to bring balance to our ecosystem.
If you are a garden enthusiast who is looking for ways in taking your garden experience to the next level then come go with me on this journey as we discuss how to make a living roof? This method of gardening is great as you garden above the ground, with that said lets get started.
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Lay Your Sedum Blankets
Cut to size your sedum blankets such as the ones I have used from Green Roofs Direct. Water them before you install and then lift and unroll them on the roof. Ensure all joints are butted up tightly. This example uses Sedum album also known as White stonecrop. Its a little like laying turf, you can see my guide for that here!
Roundhouse Build: Making A Living Roof
The final stage of building the roof of our roundhouse was to transform it into a garden.
Living roofs can help insulate the building below, provide pollination sources for surrounding wildlife and help the building blend into the landscape.
However, this roof is far from flat. Its made on a reciprocal frame, to create great strength for the roof without needing central posts. So a sloping garden in the round was the aim. It turned out beautifully, and we learned a lot in the process
Wait! Are you confused whats going on here? Want the full backstory? Read about the round house build up until this point first. Or do it later, if you like. Right ho onward
The above photo shows the bones that the living roof was built apon a reciprocal roundwood frame, covered with hardwood planking.
Super sturdy, as it needs to be to hold a large amount of water-logged soil on top.
The first step was applying hessian over the hardwood. The insulation going on next is recycled cool-room panels, and it happens to be a lovely shade of pink.
So to prevent looking up at the beautiful roundwood and hardwood ceiling and seeing bits of pink styrofoam peeking through when inside the roundhouse, we put hessian in between.
Recycled coolroom panels applied, to create an insulated space below. In between the rows, we fixed hardwood battens.
Next step: make your roundhouse look like Darth Vader.
Next step gravel, soil, plants, mulch. Lots of mulch. Lots of plants.
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Install Step And Dormer Flashing
It’s possible to reuse existing step flashing and dormer flashing, but the best way to get a watertight seal is to tear off the siding in those areas and install new flashing. Start by running self-stick underlayment at least 6 in. up onto the walls. This provides an additional barrier if water does get past the flashing. Cover the front wall first and then work your way up the side wall. Overlap the sidewall underlayment around the corner onto the front wall about 1 in. or so.
Install the shingles right up to the front wall. Cut a couple of inches off the vertical portion of the dormer flashing, and run the horizontal portion past the side wall that same distance. Nail the dormer flashing to both the wall and the shingles.
Make a 1- to 2-in. cut with a tin snips at the bend in the first step flashing. Run a bead of sealant on the corner edge of the dormer flashing, and then run that step flashing past the dormer flashing the same distance you made your cut. Bend the step flashing around the corner onto the dormer flashing with your hammer.
Install your next row of shingles over that first step flashing, then cover that row with a step flashing, and so on. Nail the step flashing to the wall toward the top of the flashing at the end that’s closer to the peak, so the next step flashing in line will cover the nail. Don’t nail them down through the shingles. For information about flashing around chimneys, see Installing Chimney Flashing.
Green Roof Filter Layer
The filter layer on a green roof is designed to prevent soil and other substrates as well as debris from filling the cavities of the drainage membrane. Both of our PermaSEAL 20P Green Roof and PermaSEAL 8 Green Roof drainage membranes have a built-in geotextile filter layer, making the installation process that much quicker.
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Sandwich Framing And 26 Tongue
The design of this roof resembles traditional post-and-beam construction, but without the headaches of working with heavy, expensive timber and the tricky joinery that goes with it. The posts, beams, rafters and ceiling ties are built-in-place sandwiches of common 2×4, 2×6, 2×8 and 2×10 smooth cedar lumber. The center board of each sandwich is 2 in. narrower than the outer ones, which lends attractive shadow lines and architectural heft to the building.
This triple-thick assembly method makes the framing members very strong, which allows for longer spans and wider spacing between members. This technique allows you to overlap and lock all the pieces together for a very strong framework, easier nailing and tighter joints. And, by assembling beams in layers, theyre lighter to lift. Since the rafters are so beefy, you can space them 32 in. apart. But those wide spans call for a roof decking that can handle those spans. Tongue-and-groove 2×6 decking fills the bill nicely because its very strong, reasonably priced and easy to install. It also looks great on the inside. You can let butt ends of the roof decking fall randomly throughout the roof its not important that they splice over framing members. But the seams will look more polished if you use a block plane to carve a little chamfer on decking ends where two boards meet.
Outdoor Living Room Overview
Theres nothing quite like kicking back on your own Patiountil the sun starts cooking you or the rain begins to fall. But you can easily double your time in the great outdoors with this beautiful pavilion. Just thinkno more rainouts during your next barbecue! And with a roof, you can relax on dry, clean, comfortable, padded furniture, which just cant stand up to the elements on an open patio. All in all, you can give your patio the feel and function of an outdoor living room. But the best part is, this pavilion will add real beauty and value to your home by dressing up that lonely, underused space.
While this outdoor living room design may look complicated to the novice carpenter, dont be intimidated. If you have the basic hand power tools, can handle a circular saw and have a bit of remodeling experience, you have the moxie to pull off this project. Well show you some scribe-it, nail-it-up and cut-it-in-place techniques that greatly simplify the tough spots and speed up the project. In fact, another carpenter and I built the basic structure in three leisurely days and spent a fourth day finishing the decorative column skirts. Give yourself and a helper about twice as long and you may finish faster than you think.
Comparing the before and after photos, you can see that in addition to building the pavilion, we did some major stonework and planting. Those improvements aside, our total materials bill was roughly $4,000.
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Cut Your Waterproof Plastic Layer & Protective Fleece To Size
You will need to apply a plastic waterproof sheet of plastic to the roof to ensure that any moisture from the living roof does not seep into the actual roof! To apply your plastic layer, simply use a stapler to staple the plastic into the timber frame.
Repeat the process with the protective fleece layer. This layer will further protect the roof from the roots of your sedum/turf and allow it to simply sit on top.
Benefits Of A Green Roof
There are several benefits to having a living green roof on your property, whether its on a small structure like the one we installed, or on home roofs, workplaces or sheds. They include:
-
Sedum is easy to propagate by division
Mitigating water runoff and subsequent overflow into the sewage system.
- Soil and vegetation acts as a sponge, absorbing and filtering water that is normally taken into gutters.
- The plants remove air particulates, produce oxygen and provide shade.
- Green roofs help to cool the air as water evaporates from the leaves of the plants a benefit in urban areas in a warming climate.
- Green roofs have a biophilia effect, softening hard structures and making us feel better.
- Green roofs can provide safe, secluded spaces for wildlife and pollinators.
- They provide great views for you and your neighbours!
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My Roof Both Lives And Dies
I made my roof back in 2012. How happy I was when I planted my flowers and succulents. Three months later, I had lost my smile, and so had my roof. There is no rain for five months of the year where I live, and of course the top of a roof is blazing hot. Everything died. So I came up with another plan: the semi-dead roof.
In summer, I cover the soil in dry grass cut from my garden. I have learned its easy to shape the straw by spraying water over it. The straw effectively insulates the house from the furnace-like heat. When winter comes, the dry grass rots and seeds, creating a lovely green roof. The fresh green growth prevents the earth from eroding in the heavy rain, too.
How To Build A Green Roof Garden
The steps for installing a green roof are relatively straightforward, but they can vary slightly depending on your needs and goals.
The first step will always involve one or more layers of waterproofing material over the existing roof. These membranes will protect against water damage, which is essential for maintaining the roofs integrity.
The installer may also add an inorganic root protection barrier in between the soil and the waterproofing layer. Some roof coverings, including spray-on membranes, contain chemically organic substances such as bitumen or asphalt without a barrier, plant roots could spread into these coverings, affecting those substances and causing them to rot or lose their protective properties.
Additional layers of insulation might be needed in colder climates, and a mat to facilitate drainage may also prove helpful.
Green Roof Structural Requirements
The structural requirements for a green roof are the most important aspect to consider. You need to make sure that the structure can cope with the extra weight of your green roof, especially when saturated with water. Additional structural support may need to be provided.
Most extensive green roof designs with sedum and other simple lightweight plants weigh between 60-150 kg/m2
Important note: Any weight calculations for green roofs must factor in the weight of rain and snow when the substrate is saturated, as well as the various components of the system.
With semi-extensive and intensive roofs, you will need to consult a chartered structural engineer, architect or surveyor around structural loading.
