Permaculture sod roof (green building forum at permies)

Permaculture sod roof (green building forum at permies)

We have a foot-deep sod roof.  The builder loaded it, over 400 square feet, with a heavy clay soil and without any drainage or gravel layers.  We've had problems with drainage.  One half of it gets heavy sun and is quite dry, the other gets more shade and stays wetter.  Right now it grows a mix of a winter rye combined with wild seeds that have blown up on it.  Our climate gives us deep winter freezes, heavy snows, lovely springs and falls and summer heat.


We are also a Montana based home.With a green roof structure.This one however was carefully designed and built to utilize a bit lighter load then what yours has been.

A previous home passive solar home  my other half designed, built and constructed utilized a top soil depth of 2 feet.However it was removed after a gang of gophers moved in making one heck of a mess through the liner as well as enjoying the the tasty insulation package.

So let me give you a bit of information from my green roof designing and landscaping experience.

First off I am not sure what your builder was thinking, LOL. my opinion anyhow.Roof gardens can be very viable living and growing spaces  to utilize. We designed ours to be  another entertainment area of our home as well as beautifully landscaped very detailed out with sedums growing with in design patterns.We also have a stone patio and 2 good sized stone planting areas there as well.

Do you know what your roof liner is composed of. If you have a a good epdm liner? Do you know if your home roof system was built with a  pitch for drainage? Living in Bozeman you may have the insulation system built out of Belgrade that comes with a pitch for drainage.Is there drainage in place around the building such as a french drain to direct water away from the homes wall?

Do you have any idea what the bearing load for your roof actually is designed for? If I  just take of from the amount of fill that your builder placed on the roof structure I can offer some suggestions provided he was good about sticking to the design guidelines and did not push the limits..

If this is what your roofing system is composed of I can offer you some suggestions for you to consider to turn. it into a productive space. This  is going to be work for you if you decide to change it.

First off find out if the clay pack is directly over your liner or if they put in some type of barrier to protect it from  stone movement or critters .Many commercial roof gardens are also covered with a drainage type system that is placed under the soils.This is important because you will be removing this  the soil from the home.Adding mulch and trying to improve the soils on the roof will not help with the drainage if your wanting to grow plants that do not thrive in a clay type base.With the amount of clay sitting on this roof  you may wish to fully remove it  and put on something that is more productive plant friendly.You may wish to also add in walking areas.If your weight load allows you may add some hardscape choices as well..Make sure your liner is protected and then you could go about replacing with an equivalent  amount of good grow mix.You can also do this with a sheet type method like lasagna gardening. the Ruth Stout methods, even the straw bale types of gardening allowing for break down over a couple of years with it as a grow medium etc. Personally myself when I design a roof garden I go the lighter custom soil mixes that I blend myself.

Permaculture sod roof (green building forum at permies)

There are 3 types of roof garden forms to look  consider intensive, semi intensive and extensive..What you basically have  with a sod roof and are looking to establish is a semi intensive garden.You just need to trade out your growing medium and not just add to it with a weight burden from additions and more water holding capacity which could push it past your weight bearing load.

Better soil on your roof with a proper drainage is better for the roof structure itself.The  run off into your outer drainage I assume also goes into an area of for productive growth.

The roof on our home is designed with both semi intensive usage available if I so choose to put it into affect,However my personal choice has been to keep it extensive using light growing mediums and very low care plants.

Perhaps this can offer you some thoughts to consider.


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