What Is The R-Value Of A Green Roof?

What Is The R-Value Of A Green Roof?

What Is The R-Value Of A Green Roof?

Dry growth material (the “soil” of the green roof, so to speak) has a low R-value (usually about 0.5/inch). Plants require water to flourish, thus, the green roof is intended to retain some moisture. The “R” stands for resistance, as in thermal resistance.

So, when wet, its R-value approaches zero, which is pretty low. When dry, its R-value is as high as it can get.

Green roofs (which are just vegetated roofs) have limited thermal performance. This means they are not very good at minimizing heat transfer through the building (particularly through heating and cooling ducts).

They can help a little, but by themselves, they will not eliminate all heat losses from the building envelope.

What Is An Intensive And Extensive Green Roof?

An extended green roof will most likely have a shallow layer of substrate that covers a vast area, whereas an intense green roof will often have a deeper layer of substrate that is restricted to fewer sections.

Also, an extensive green roof will often have a less sophisticated drainage system than an intensive green roof.

An intense green roof may be comprised of many smaller planted modules, rather than one larger one. Some think of this as one large module (one large void with many plants), whereas I think of it as many smaller ones.

It can be argued that larger ones are easier to maintain and care for, but many smaller ones are also easier to design and install (because they are modular).

Also, it may be more cost-effective to install numerous smaller modules over a large area than it is to install fewer larger formations over the same area (assuming the formers can be installed in less time than the latter could have been installed).

What Is The Drainage Layer In A Green Roof?

A green roof drainage layer is often an HDPE (high-density poly ethylene) membrane that holds water in cups for plants to draw on. Excess rainfall is channeled through holes in the storage cups called super-saturators.

It is important that the drainage layer does not act as a secondary water barrier (this is different than the waterproofing layer, which prevents water from getting through at all).

A secondary water barrier will force more water to “escape” through the substrate than otherwise would have done so.

If a green roof is built without a drainage layer (instead of relying on a waterproofing layer to direct excess rainfall away from the waterproofing layer), then much more of this overflow must be directed into the soil of the green roof by other means.

This can be done with vegetation or micro-porous materials in the substrate.

Does Green Siding Go With A Brown Roof?

Yes. Green and brown combine nicely for a truly wooded vibe and a sense of nature. If your roof is dark brown, you may use any shade of green you like. If your roof is a lighter color, dark green will stand out. It will also stand out in a lighter neighborhood.

Green roofs are a very interesting and effective addition to any home. They are boring, but they are beautiful, innovative, and eco-friendly.

Green roofs come in a wide array of colors: gray, grayish-blue, green, blue (most people’s first choice), and even black if the roof is shiny enough (previous link).

Brown roofs can be grays (such as our green roofs) or dark browns. But green should not be used with noticeable dark grays – it should be used only with light grays and light greens that stand out against the dark-colored roofing surface.

Can You Put A Green Roof On A Shipping Container?

Green Sedum roofing systems may be installed on top of shipping containers, however, we don’t advocate laying Sedum directly on the container roof since moisture can be trapped, accelerating deterioration.

It would be better to use a waterproofing layer over the container, such as a layer of mineral wool or woodchip board, followed by a drainage layer atop the remaining waterproofing.

Some containers are built with a deck on top and can be used as living/working spaces inside. They may not have been designed to stand up to storm conditions – they usually have low roofs and poor insulating properties.

It is very important that you seal all openings in the roof and wet line (the area inside the roof where water comes in) before adding plants or taking on any other sort of use.

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