I just bought a house with NO attic ventilation at all, and was wondering which direction to go: installing turbine vents, having a radiant barrier installed, or having foam insulation put in. Which would keep the attic the coolest and keep my electric bill the lowest? I have absolutely no shade on the house, and my attic gets hotter than an attic usually is normally. Thanks for the help.
2 responses to What is the difference between foam insulation and a radiant barrier, and which is more effective?
Great questions. If you have absolutely no ventilation, you really need to have that fixed first. Ventilation keeps your attic cooler but also keeps it from holding moisture. Moisture will greatly lower the effectiveness of the regular insulation in your attic.
Next, look at the radiant barrier. It does not slow down and store heat like foam or other thick insulation’s, it simply does not allow heat to radiate off of itself. Foam will slow down the heat transfer and store it in the attic for awhile after the sun sets and the roof begins to cool. It also typically costs about three times more then a radiant barrier and does not provide the same savings in most cases.
The insulation on the floor of the attic also needs to be increased to the department of energy recommendations. Typically, an R-49 in the Dallas TX area which is where I live.
With what you have described, I would say that your priorities need to be the ventilation first and then radiant barrier and insulation.
What is the difference between foam insulation and a radiant barrier, and which is more effective?
I think you could do all three, but if you have the access I would go with the attic fan vented through the roof (you should have gable vents at each end of the attic and vented soffit in the eaves) and enough fiberglass insulation in the joists (thickness depending on your location). I believe the radiant barrier would be effective but I think it has to be placed between the roofing plywood and the roof rafters, which would make it a large expensive job.
What is the difference between foam insulation and a radiant barrier, and which is more effective?
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