DIY green roof installation video

In Principle, building a green roof can be as easy as it looks in our Green Roof DIY installation video, assuming you have some construction skills and your roof isn’t too complicated. Our green roof was a single a 2/12 pitch, so it is as easy as it will get, but remember the stakes are pretty high if it leaks so you would need to be diligent about it. Here is another page that may help - 

All you need to know about Living Green Roofs

By that I mean – if you follow the manufacturers guidelines for membrane installation in terms of overlapping and taping and sealing like we did in that video, and you don’t wear golf shoes while doing it a put a bunch of holes in it, there is no reason why it shouldn’t work.

In that video you saw us lay down the initial waterproofing membrane with primer as the last line of defense, but that actually becomes the ‘backup’ membrane since once you lay down the poly root barrier (the green one in the video), the water will drain off that. And once it is covered in dirt it won’t deteriorate with UV. Then it is the drainage cup layer followed by dirt.

You can see the green roof materials from Dorken systems here, there are of course others to chose from, but the basic techniques for install should be about the same – Keep the water out, keep the roots out, store and drain water as necessary. If you do it, let us know how it goes!

I want to make sure I understand – you plan to  strip it back to the T&G and then build up, and since the T&G is the interior finish that means all the insulation is on the outside? The reason I ask is because the way I read it is that you are planning to have only 3 inches of EPS (R12) as your roof insulation and that is about half of what would be required by Building Code, and building just to meet Code won't help you in terms of energy efficiency - to think of it in its true essence, 'Building Code' requirements  are the defining point of the worst performing house that you are legally allowed to build. This page explains in detail - 

Why better insulated houses are worth the money

There are a number of ways you can go from here, but to stick closest to what you have proposed I would lay down at least 10 inches of EPS, which would be about R40. To do that you will need to fasten it with long screws, those are pretty expensive and they will act as a thermal bridge that increases heat loss, but its similar to the assembly you have described and would probably be one of the more affordable ways to proceed. So it would not be my top recommendation, but it’s a bit more inline with what you are proposing. That would be –

• A ‘peel and stick’ air and vapor barrier membrane covering the wooden roof deck
• Rigid foam panels
• Drainage plane membrane
• Vertical strapping (for air space)
• Horizontal strapping (To accommodate metal roofing)
• Metal roofing.

Any alternative method, and any that are preferable but more expensive, would probably start with adding new roof trusses then insulating in the bays with Rockwool or perhaps cellulose (here is our page about how to choose the best insulation) You would then need to add sheathing and a drainage plane, then the strapping and metal. here is our page about How to choose

Rather than try to lay out a bunch of options, I will wait for a reply to make sure I am understanding your intentions correctly and to see if other proposals would far exceed your budget.

And yes to ventilation as you mention - make sure air can flow and water can drain right below the metal. We don't have a dedicated page I can reference, but here is our page about how to install siding so walls can dry, you would need to adhere to the same general principles with your roof.