If I had to pick,the foam insulation is a better investment in my opinion.
- Metal roofs have Energy Star certified options which can improve the building's performance and lasts a long time but is very expensive.
- You can also get standard asphault shingles today with a similar Energy Star rating from companies like GAF which is much less expensive.
You have more wall area than roof area by far.
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Check our green roofingQ&A to see what homeowners and contractors are sayingabout the pros and cons of white roofs, metal roofs, asphalt, etc.