Green Roofing Just Got Easier

By: Stephen Milioti, This Old House magazine

plastic containers to allow plants to take root

Planting Modules: Plants take root in 2-by-2 foot plastic containers instead of on layers of materials laid directly on the roof, so extra waterproofing and drainage measures are unnecessary. The waffled trough directs excess water into its gutters, a sort of reservoir for plants. Wet, a square foot weighs 15 to 18 pounds. An engineer must OK the load.

premeasured sacks of soil help ease the job of spreading growth medium

Soil: The job of spreading growth medium over a large surface is eliminated by premeasured sacks. Each fills one module.

plant sedums come in five premixed combinations

Plants:Sedums come in five premixed combinations. This one blooms red in autumn and yellow from June through July.

a liner helps filter, hold wet soil in place, and controls unruly root growth

Root and Soil Barrier: A mildew-resistant liner for each tray acts as both a filter fabric, holding wet soil in place, and a physical barrier to unruly root growth—functions often addressed with separate components.

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Easy Upgrades That Say Welcome Home

Not that you can't find the engineer, roofer, nurseryman, and architect to professionally install a green roof. But everyone loves an option that cuts out extra labor, materials, and middlemen. That's why the eco-obsessed editors here at This Old House had to see GreenGrid, a DIY green-roofing kit. Its freestanding modules ostensibly give the same benefits as green roofs the experts install—if your roof's already sound, fairly flat, and watertight. Don't bet on the same polish as with a pro team. But you may see the usual improved cooling and heating and reduced rainwater runoff. (We'll see how our kit fares.)

Developer Weston Solutions, an environmental consultancy, installed pro versions of the modules for years before scaling them down into a system that average joes can use. "Water them for a year. Little additional maintenance is needed," says market development associate Jim Lindell. However, no arid climes, tar roofs , or slopes sharper than 15 percent. $10-$15 a square foot; greengridroofs.com.

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