Sustainability benefits and costs of green roofs in modular home construction

WHAT IS A GREEN ROOF?

A green roof is simply a way of recreating the displaced natural landscape on top of your home. Beyond the obvious aesthetic benefits of these natural roofs, there are many environmental and wellness benefits to them as well.

It is well documented that exposure to nature benefits people in a myriad of ways, including reducing stress hormones, blood pressure, heart rate, and muscle tension. Therefore, adding greenery to sight-lines throughout the home that may not have them otherwise is a major wellness benefit. Many green roofs will also be habitable spaces which can provide outdoor spaces that might be unavailable on some properties. Additionally, the soil can serves well for noise reduction if the home is located near a train, heavy traffic or everyday city sounds.

The environmental benefits arise from the fact that the plantings above the roofing materials will be absorbing sun, wind, and rain. This leads the a reduction of rainwater runoff that would normal flow through drainage systems and municipal septic systems, absorbs heat that may transfer through the roof into the home's interior. Additionally, by absorbing sun, wind and rainwater the green roof will extend the life of the roofing materials and membranes below.

HOW DOES IT EFFECT BUILDING COSTS?

The upfront costs for a green roof will be significantly more than a conventional roof but if they are designed and installed correctly the lifecycle costs may ultimately yield a long term cost savings.

Simply put, a green roof in our area will cost $25 to $40 per square foot. This does not include the waterproof membrane below the green roof nor any irrigation system (if necessary.) Additionally, this does not factor in the costs associated with maintaining the growth on the green roof, which is particularly critical in the first few years after installation. All these numbers add up quick! However, the long term benefits from reduced utility costs could very well make up for that initial loss over time.

It is also important that we are studying whether our homes will need any additional structure that may be necessary for homeowners who want a green roofs. Having this conversation as early as possible can reduce any unexpected building costs and leave you with a natural oasis on top of your home.

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