A Room With a Green Roof View

I'm a roofer and although and not a fan on modified bitumen roofs, this roof will not leak (assuming correct installation) for some time. The reason is the slope of the roof that will let the water run off instead of just ponding on the roof. That is the only good thing about this roof (my subjective opinion of course).

Now, if you are planning a green roof to be installed on your home or building, i strongly advise against installing it on roofs such as modified bitumen, EPDM rubber roofs and built up roofs (tar and gravel, 4 ply, etc). I highly doubt there are commercial flat roofs with rolled asphalt, so I won't mention anything about those. But here is the reason why you should avoid the above roofing systems whe considering a green roof:

All of the above roofs (except mod. bit.) rely on adhesives which just break down ofter only a few years. Mod. Bit. could be either peel and stick or torch-applied so both adhesives and meting process for seams application, but in either case, those seams don't last too long, requiring a roof repair after a few years in service.

Also, unlike the green roof in the pictures above, most flat roofs a just that - flat - and many have pre-existing problems with ponding water. Therefore putting a roof like modified bitumen and berrying it under 4-6 inches of soil just calls for problems. Just imagine removing a green roof to trace roof leaks... not fun, and not very profitable :)

In my opinion a 80-mil commercial grade PVC roofing systems like IB Roof or similar should be installed. By being designed around hot-air welded seams (which when put together properly, are permanent, as there is no chemicals involved), such roofs provide a VERY long watertight protection and combined with a green roof can last in excess of 50 years. Besides being a much better waterproofing system PVC roofs are also light-weight compared to 2-ply mod bit roofs and do not require such a beefed-up framing as other older roofs, so you can put more soil on the roof and make it even greener.

Going back to the roof in question, what concerns me the most, is the drip edge (I assume it is for water collection), skylight and the stink-pipes. The pipes are of the most concern to me, because it seems like the ate flashed using an aluminum pipe flashing used for asphalts shingle roofs, and these flashings need at least 3 to 12" slope. Those are obviously heavily caulked, but still, under soil and water freezing - unfreezing, these will be the first to leak.

As for the skylight - I just do not like how mod. bit. flashing works... I give that skylight no more than 7-10 years until it leaks.

Zinco has nothing in any of their assembly with any plastic as part of the roof.....condensation is going to be evident inside the building when moisture is forced back into the building....

sorry this is not good for the building....."Green Roof Advocate"

I have done my homework and in fact you dont have but 1 or 2 projects to your name to the point buyer beware.....I found not one single reference or media release not written buy the owner. As most systems they will sell to anyone for a price, in fact the only one who will pay in the long run is your client. With all sincerity luck be with you as so not to make the rest of us consultants have to work harder cleaning up your mess. At least become an expert in one system and not an advocate of being a slave to the economics sacrificing function. Make sure you tell your clients that you are importing non-American made goods too...to the remainder of the public my apology here we have a wolf in sheep's clothing, Ill be glad when they formulate guidelines for the "Green Consultant"....

To anonymous "buyer beware" blogger:
The roof is actually not asphalt. And, it passed an extensive flood test. It is under warrantly to be watertight underneath the green roof. Prevegetated mats--while often appropriate for some situations--were a more expensive option and the client preferred the warranty and track record of this system by Zinco. If necessary, these systems are easily removed and repaired. When the site calls for a modular system, we use one but in this case, a planted in place roof was the best option both in terms of time and money.

The comments by the fan of prevegetated roofing (which can be great!) is wrong on every single point she/he makes. This roof will have a long and healthy life.

There are huge concerns here......plastic layer over rolled asphalt roofing....OUCH! can you say condensation. In addition asphalt roofing is not waterproof, it is water resistant and wont do well with sitting water. Beside the fact....way too much labor and "Layers of Material" to complete the "Sandwich". Since they will eventually have to access the waterproofing, digging through all the layers of rolled material will eventually destroy the roof. This roof could of been done in 1/3 the time and half the cost with a pre-vegetated panel system and its easily removable when you do have to repair the leaks.....

I love the info in this post and the great pictures. But one thing is missing. Did anyone check the design loads of the roof. This is critical, if people think they can just start throwing soil, stone, plants and added water weight to there roof and not have a problem they are mistaken. The roofs are designed to hold what they have now. Some additional bracing may all that is needed but if not designed for the proper weight roofs will be collapsing and injuries may occur. Have someone calculate the added weight and then check the design loads of the roof system before adding a green roof.