Example of a TPO Roof installed over a new addition with more insulation
The low slope roofs of Krisana Park are fairly expensive compared to conventional asphalt shingle roofs. The good news is that membranes have improved a lot over the last couple of decades. When installed properly, both EPDM and TPO can last a very long time. They are flexible and don’t crack or become brittle as the crazy strong sun here in CO tries to break everything down. Also, they can handle expansion and contraction as they heat up and cool down each day, are buffeted by winds, or hammered by hail.
A good strong TPO membrane example
The additional challenges, as others have noted, is that there is nothing under the old insulation, so a lot of old debris will inevitably fall into your home once it is stripped off. As an architect, what I notice is that the nice existing thin fascia (2x6 or 2x8 redwood roof edge) won’t hold all the insulation that is now required by code (sometimes only enforced for new construction). So beware that you might end up with a much thicker and chunky looking new roof on your house!
If you go with more expensive high density insulation (poly-iso or polyurethane), you can get somewhat close to the old overall thickness, but it will still grow in depth by an inch or so.
Another option is to step down the insulation at the overhangs. You don’t need to insulate in these areas anyway, so talk to your roofer to see if they can pull this off - the membrane will either taper or round off and down to the thinner profile along the eaves.
For a good 60mil heavy duty membrane, new higher quality insulation (EPS is not good – it can absorb water), a walk board for protecting the insulation, new roof edges/fascia, gutters and downspouts, etc., you are definitely going to be over 30k.
Roofworx did a great job with a white TPO for our house. A white roof will last a little longer and provide some energy savings if you use air conditioning, however as we are heating more than cooling here in Denver throughout a typical year the savings won’t be that substantial.
Example of electrical conduit being installed for light fixtures before roof insulation goes down
What have your experiences been? Many of the roofs are still using the older materials of Bitumen and Built-up techniques. How have these help up if you have replaced one recently?