Green strategies for building, retrofitting and remodeling minimize environmental impacts by matching low-impact materials and energy-efficient designs with local resources and climate factors.
It's all part of sustainable design — the movement that aims to reduce the load domestic living has on the environment by extending the useful life of construction and conserving resources. When greening housing projects, the choices you make should take numerous factors into account.
Choosing materials and methods that make your home more energy- and water-efficient, less toxic to the environment, and longer-lasting can be complicated and time-consuming and may impose higher up-front costs, but for the long term, you'll have a structure with lower maintenance needs and costs, lower monthly bills, and a smaller carbon footprint.
The following tips will help you understand how your roof and water management, or drainage, system offers enormous opportunity for green improvement. The third and final installment in this series will discuss windows, doors and energy systems.
Roofs: Top priority
Roof performance is paramount for any type of building. The roof protects a structure from leaks, and in this there is little margin for error. If walls take on water, mold and mildew can grow over time, and materials and insulation will deteriorate.
Roof leaks result from weak points in areas where joints have not been sealed properly or time has eroded the seals. Installing proper flashing (leakage protection barriers) is important and should be taken very seriously.
Because roofs have multiple joints prone to leakage, many pre-form products, including drip edges, step flashing, etc, are available. Whatever roof design and materials you choose, each step should incorporate flashing.
There are many materials available for roofing, and the greener options tend to be pricier. However, several of these options last longer and are more durable. As with anything, research performance claims on any product or material.
If you are using metal, galvanized metal in a light, reflective color will help prevent solar energy from penetrating the roof. Metal is also lightweight and contains some or all recycled content.
Greener options for shingle roofs include slate, which is very expensive but incredibly long-lasting, and durable materials like tile, cedar and terra-cotta. Gravel-covered, asphalt-impregnated felt shingles, which are thicker than conventional asphalt shingles, are said to last as long as a metal roof.
There is also recycled shingling that may last as long as 100 years, with many manufacturers offering lengthy warranties. Such products eliminate harvesting of virgin resources and can be recycled again in the end. They are also much lighter shingles, so they are easier to transport and work with, and are a good alternative to asphalt paper shingles, which have a fairly short life as roofs go.
Since roofs are an area of heat loss, as well as heat gain in summer months, insulation and dehumidification will help to ensure against unwanted energy transfer that greatly improves your home's comfort and eases the strain on your wallet.
When planning a new roof there are several factors to consider:
Weight. Heavy material requires greater support.
Durability. Temperature fluctuations can affect many materials.
Water management. How water runs off the roof will affect many aspects of your home and the ground around it. Consider the material's affect on the capture and/or diversion of water.
Energy rating. The material's response to solar energy is important because it could hold heat in the summer and increase cooling requirements and costs.
Fire rating.
Maintenance needs. Find out how when the roof material is likely to deteriorate in your climate.
Installation requirements. Take into account how much energy and chemicals will be needed to complete your new roof.
Greenbuilder.com and other Web resources have more detailed information on roofing materials.
Living roofs: Going further
Also called "green roofs," a living roof can take the footprint of your home and replace that lost green space.
They can be costly to implement, but can last a lifetime. They should never have to be replaced because the decay factor is extremely low.
Living roofs neutralize radiation and thus retain heat in winter and keep the attic cool in the summer — lowering energy bills year-round. They are nontoxic (although the waterproof membrane you select could give off chemicals over time and may not be suitable for edible plants) and boost oxygen around your home. They suck up rain, and thereby reduce runoff pollution. They look amazing. And as a rooftop yard or garden, they offer a place to relax.
In cities, living roofs have the potential to reduce the "heat island effect" (the phenomenon where concrete and asphalt urban communities, characterized by a lack of green space, attract great amounts of heat, from 2 degrees to 10 degrees higher than surrounding rural communities). Heat island effect increases peak energy demands, air-conditioning costs, air pollution and heat-related illnesses.
From just above the trusses, green roofs have about nine to 13 layers — roof decking; primer; a waterproof membrane; drainage layer; insulation; aeration layer; plastic sheeting; gravel, landscape filter fabric, bark mulch and soil to retain and reservoir moisture; and finally plants.
You also need drainage around the perimeter of the roof, drip edges and other water diversion aspects discussed below.
When considering implementing a green roof, consult a professional experienced in this area. There are also numerous resources online, including the Massachusetts Low-Impact Development Toolkit Green Roof Fact Sheet, at www.mapc.org/regional_planning/LID/green_roofs.html, that discuss what is involved and address materials.
Water management: Runoff and drainage
Unless you have a living roof, all roofs — green materials or not — are basically impervious cover, and that means when it rains, runoff begins.
All the water and any pollutants from and on your roof will run off into your lawn, where some water may be absorbed but also additional chemicals will be picked up, and then into the asphalt street. From there, it picks up more chemicals and pollutants (such as car wash cleaner, motor oil, etc.) and it is channeled to the nearest water source — whether directly or through storm drain systems.
What's worse is that if you live in an area with combined municipal sewer and storm drainage systems (much of the Northeast U.S.), runoff combines with sewage, and when the flow exceeds the municipal treatment plant's capacity, the overflow — sewage and all — blows out system overflow points directly into surface, fresh and ocean water resources.
By adding gutters, rain chains, rain barrels and cisterns to your home, you can capture the rain water coming off your roof and greatly reduce runoff, and possibly some impact on basement flooding problems you may have. You can use the captured water for gardens, landscaping, house plants, etc., reducing your potable water consumption and water utility bill. Be sure to determine if your roof materials contain chemicals that will leach into water, and decide how to best use captured water.
The Massachusetts Low-Impact Development Toolkit Cisterns and Rain Barrels Fact Sheet can help you get started with this green quick fix retrofit: www.mapc.org/regional_planning/lid/cisterns_barrels.html.
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Andrea Fox, a Beverly resident, has been writing about environmental sustainability and eco-topics for eight years. She is a member of the Society of Environmental Journalists and a watershed protection advocate in Salem Sound Watershed.
