[Greenbuilding] Green roof drainage question

[Marilyn]

Hi List:

Here's the problem, best as I can state it.

When I had my green roof put on the addition to my home, the roof came higher than 
the place it would have been without due to necessary engineering, so the 'ground level' 
is only about 2 inches below the door sill where I go out there.

For a couple of years in a row now we have had much snow and a giant fast thaw in 
February.

What seems to be happening, best as I can figure out, is that the sun has sort of 
'glazed' the surface of the ground due to the sun and cold so when the rapid thaw hits, 
the water cannot get to the normal drainage channels, and because the glazing has 
evened out the roof surface and counteracted the roof drainage slope, the water backs 
up through my door and causes mucho damage.

I've been trying to figure out what to do for a couple years now, talking to 
contractors, none of whom seem to be familiar with green roofs or have run into any 
similar problems, so they're winging it with the  ideas.

One idea was to put a drain right in front of the door that would tie into my washing 
machine drainage below - would mean keeping the drain clear all winter, but that can be 
done unless we get enough snow that I can't open the door to the roof, which has 
happened.  The biggie with this one was that the contractor couldn't figure out how 
and where the drain needed to be sealed with all the layers (torch-down, root barrier, 
drainage layer etc) of stuff he was unfamilair with.  He consulted a roof and a plumber, 
but no joy.

The other idea was just to keep dumping lots of de-icer in front of the door so that 
the water had a place to get down to the drainage layer, but my hesitation with this is 
that with only 6 inches of light-weight soil mix, wouldn't the drainage channels in the 
mat likely be frozen?  Could this actually work?

Sorry this is lengthy, but I'm trying to explain something I don't really have the 
language for, nor likely a full understanding of the situation.  This is the worst part of 
'going green' is that there's no help from contractors when things go wrong since most 
of them haven't a clue and won't even (and don't want to) think about it or learn.

I hope some of the group here has some ideas or can evaluate the ideas above - or 
anything.  I'd be most grateful for any inspiration or guidance.
TIA,
~marilyn


Cybercrone
http://www.eol.ca/~cybercrone
Hm-m-m-m . . .
In arithmetic as in politics, the importance of one
is determined by the number of zeros behind him. - Unknown

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