Today we're at the home of architecture professor and author Vidar Lerum and
designer Lori Pawlias to talk about a stormwater management strategy that
requires a little more planning and investment. I'm so excited to show this
to you, it's a green roof! Now, a green roof is topped with a layer of soil and
plants to absorb or slow down rain water that would otherwise rush off a
traditional roof. So let's go check it out. What made you decide to put a green
roof on your house? [Vidar] Well, my main intention was to do a house that was
very efficient in terms of energy and green roof is one strategy. [Eliana] So, what sort
of preparation do you do on the roof in order to make it a green roof? [Vidar] We had to
consult with a structural engineer to decide how much weight we could have regarding soil.
We have a roof membrane on the roof. It's a small slope on the roof. On top of that is an interesting product
that this both a roof barrier and a drainage layer so that the water can
drain off under the roots and the roots will not go down into the roofing barrier. So,
that's the first and then the mixture of soil comes on top of that, and then the
plants. [Lori] So then I started to design a soil mixture that would be eight inches deep
I had to adjust the different ingredients to the mix so that I could
keep it within that weight frame. My experience in the greenhouse was that
when you buy a bag of potting mix that when it dries out it's permanently dried out
and you cannot re-wet it so by doing my own I was able to create a mixture
that would be able to be re-wetted and it could go through
periods of droughts as well as periods of flooding and it would be able to
perform. As far as the plants, there are weeds up here! They seem to be able to
thrive in conditions where other plants do not thrive. [Eliana] The do at my house! ] [Lori]Yes and they do at
everybody's! You can't seem to kill them! We included weeds that grew by runners
rather than by seeds because we did not want to spread our weeds into our
neighbor's yard. [Eliana]What happens to any water that can't be absorbed by the soil
or plants. [Vidar]I have arranged it so that water goes to a drain pipe on the roof
and the drain pipe leads to a scupper on each side of the house and then under
the scuppers I have put a sheep tank, actually, in the ground filled with rocks.
So, that absorbs water and from there it goes into a drain pipe underground, it
waters plants from from below underground so it all goes back in to the ground. [Eliana]So, does this mean
that there is no stormwater runoff coming off of your property? [Vidar] Right,
there's no storm water coming off the property even the driveway is permeable, so we
try not to bring any water back into the sewer. The city of Urbana still charges us.
(Laughing)
[Eliana] Of course they do! (Laughing)
Can you talk about some of the costs involved with a green roof? [Vidar] We had to make sure that the roof
was structurally sound, and I used I beams that have the thickness that would
easily take on an extra load. There is a cost putting in a drainage layer.
It was fairly inexpensive, and then the soil mix, and the plants are really not more
than what you would do in your garden anyway.
[Eliana] Are there any benefits beyond stormwater management? [Vidar] In the winter the
temperature on the roof will not go below freezing which is interesting even
if we have sub-zero temperatures and in the summer
typically the roof will not get warmer than the plants and the plants
don't get much warmer than the air temperature.
So there's a great benefit in the temperature differences which means that
you spend less cooling the house summer and then spend less heating in the
winter. [Eliana] So you have a very energy-efficient home. [Vidar] Yes, but that comes
from the green roof is one part of that, but also passive solar gains in the
in the winter, shading the windows in summer, I have a solar collector that
produces hot water and goes to underfloor radiant heating. So all of
those measures together and in the well insulated house means that we have modest energy bills.
[Eliana] Green roofs and other practices highlighted in this series allow you to
capture water on your property, but what if you can't pull back every drop? In the
next episode of storm water at home we'll talk about what you can do to
ensure the water leaving your property is clean enough to flow into our waterways.