You have asked the right question but at the same time you have answered some of the basic questions in determining a solution.
Choosing a roof
First, your 2:12 pitch roof. Because of your geographical location and known high winds, I would recommend looking into a standing seam metal roof.
- This approach will allow you to handle some of the worst weather conditions and comply with the Miami-Dade regulations common in most counties in Florida.
- One roofing type which meets Miami-Dade regulations is the UC-3 standing seam metal roof profile manufactured by Firestone Metal Products.
Insulating the roof
Second, how to insulate. Contact local foam insulation contractors and discuss a hot deck installation process of insulation. This method fills all of the roof cavities (in your case between each rafter) solid with blown-in foam insulation.
There are two types of foam currently available on the market.
- Closed cell foam - approximately R-7 per inch thickness of insulation.
- Open cell foam - approximately R-4 per inch thickness of insulation.
Third, reducing the A/C and heating bills. Obviously installing blown-in foam insulation will reduce heat gain as well as heat loss.
However, you can go one step further to reduce the heat gain by choosing a roof color with a high Solar Reflectance Index (SRI).
- A roof color with a .50 index is considered to be a cool roof and will absorb less solar radiation equaling a low heat gain on the interior of the building.
- Keep in mind not all paint colors are equal, so check the SRI prior to specifying and choose a color greater than a .50 index number.
For more information:
Read "What type of roof should I choose in a hot climate?" a Q&A answered by Mick Dalrymple.
Check our Find a Pro directory to find a green roofing professional near you.