These are the main things to consider when re-roofing your roof:
Reflectivity and emissivity.
Emissivity is the ability of a material to dissipate heat that it has taken in. Higher emissivity and greater reflectivity are better. One function of your roof in your environment is to function as a huge shade device for your home. It is the membrane painted over the top of the foam that you wish to be as reflective and emissive as possible. Search for the item you are thinking about on the Cool Roof Rating Council’s website for its initial and three-year scores. The more heat you reflect away, the easier the fight for your insulation to slow the migration of the rest of it.
Normally, membranes are placed on in 2 coats. The first one is generally tinted a light gray so that the installer can verify in the second (white) coat that they have actually covered whatever two times. Make sure the coating is sprayed on in sufficient mil. density so that it lasts. It helps to clean the roof every year approximately to maximize its reflectance, and it will require re-coating in about 5 years to make sure resilience. The membrane is what avoids water infiltration.
Ensure the foam is even, without significant dips or dams. These produce ponds on the roof after rainstorms and shorten the life of your membrane, also gathering dust that reduces reflectivity.
If you don’t have quite, you can add about R-6.5 per inch with the foam. (I am presuming that you do not have access to your attic space.) I chose 3-1/2 inches with even a bit more on my partly exposed rooftop ductwork. It made an incredible difference. In between a number of insulation and weatherization measures, we need no a/c up until it is over 100 degrees outside.
Thermal barrier and air barrier positioning.
Make sure your attic is unvented. Depending upon the understanding of your original builder, you may have roofing penetrations (such as vent pipes) that just open up into the attic instead of being linked through the attic straight to the home appliance that is being vented. This will defeat the insulation worth of your foam. Conversely, any hole from a device vent pipeline through the ceiling and into the open attic similarly beats the usefulness of your attic insulation. Get rid of eave vents also, as you are moving the top of your structure envelope from the ceiling to the roof. Stop unintended air movement that bypasses your insulation.
If you have a woodpecker concern in your area, membrane-coated foam might not be the very best service as the woodpeckers might peck right into it, exposing the foam to the elements. Consult your local roofer for options, such as sheet foam with a puncture-resistant cover over it.
If you are thinking of including solar water heating or solar PV, consider having the mounting stansions installed before the foam (securing any threads with tape). It needs coordination of the different specialists, but lathering afterwards simply provides extra security that the roof deck penetrations are sealed tight. The solar specialists can finish their installation after the roofing system is completed.
Recognize that this huge shade gadget is also going to serve the same shading function in the winter season, depriving you of the substantial warming impact of the winter sun in your higher-elevation area. You can offset this by enhancing the total quality of your thermal envelope with steps such as sealing fractures, having appropriate wall insulation and setting up dual-pane, low-E squared (or low-E cubed) windows. Passive solar style can likewise make the most of the low-angle winter season sun.
Reflectivity and emissivity
Thermal barrier and air barrier alignment
For even more considerations and thoughts when re-roofing your roof, visit www.ibcroofing.com