Q&A – Concrete roof conundrum

Going from one roof type to another can feel like a big change, some advice from the experts can make that transition easier.

A Floridian homeonwer, Desiree, reached out to learn about what to expect frm their first concrete tile roof. They asked:

I am going to a shingle roof from a concrete tile one. No one mentioned anything about the attic and what will be needed there. I have a radiant barrier now which seems to be coming down due to all the contractors looking for leaks. I want to make sure my electric bills don't go up a lot because of the shingle roof. I appreciate all the help you can give me on this topic. If I need installation in the attic, what would you suggest?

A couple of our experts had answers for Desiree, starting with Andy Stofleth from V.C. Veterans Contracting LLC: 

That is an excellent question, and I'm glad you're thinking about the attic before the roof is installed.

Many homeowners assume their electric bill is determined by one thing alone, but the reality is that several systems play a role in keeping your home comfortable and energy efficient. Concrete tile roofs naturally create an air space beneath the tile that helps reduce heat transfer into the attic. When converting from tile to asphalt shingles, it is important to evaluate a few things:

• The condition of your attic insulation
• Your attic ventilation system (net free ventilating area or passive venting)
• The color of your asphalt shingles (hint: darker colors absorb more heat)

Since you mentioned that your radiant barrier is beginning to sag or come loose, I would recommend having it evaluated as part of the roofing project. In Florida's hot climate, radiant barriers can be very effective because they reflect heat away from the attic before it enters the living space. Studies cited by the U.S. Department of Energy have shown cooling cost reductions of approximately 5% to 10% in warm, sunny climates when radiant barriers are properly installed.

I would also ask your contractor to inspect the attic insulation depth and verify that your ventilation system is balanced and functioning properly. In many Florida homes, adequate insulation and ventilation provide as much or more energy benefit than the roofing material itself.

If your existing insulation levels are low, adding attic insulation during the reroof process may provide one of the best returns on investment for energy savings and comfort.

My recommendation would be:

1. Verify attic insulation levels meet current recommendations.
2. Confirm proper intake and exhaust ventilation.
3. Consider a lighter-colored or energy-efficient shingle if appearance and budget allow.

A properly ventilated and insulated attic with a lighter colored shingle can help ensure that moving from concrete tile to asphalt shingles does not result in a significant increase in your cooling costs. I would encourage you to ask your roofing contractor specifically about insulation and ventilation calculations so the entire roof system is evaluated rather than just the shingles.

Marty Stout from Go Roof Tune Up also chimed in, saying:

The type of roofing material will not affect your "electric bills." You will want to be sure that the ventilation is in accordance with the local code requirements. Check with the City and or County Building Department to confirm. Radiant barrier is very good and should be replaced if removed for repair. As far as a recommendation on insulation, again check with the Building department to confirm what is required and you should be fine. That said checking with a trusted expert in that field of construction would be wise.  

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