04:30AM | 06/16/05
Member Since: 06/15/05
5 lifetime posts
I purchased my home in may of 2004 with energy efficiency in mind.I have radiant barrier roofing installed and r-30 insulation.My problem is that I was told my attic temperatures would be around 10 degrees warmer than outside temperatures.I have been tracking attic temps for a year and am disapointed.I have attic temps over 130 degrees on clear sunny days.I have continuos soffit vents around perimeter of house and 5 12x12 vents on ridge of roof.The soffit venting was plugged and I have taken care of that problem.My home is 2200 sq.feet and is a hip roof.please help.


04:39AM | 06/16/05
Member Since: 04/25/05
1915 lifetime posts
What is radiant barrier ROOFING?

For a radiant barrier to work it has to be installed with at least 1" of air space (other wise it becomes an heat conductor). And it needs to be installed facing down or else it will become dirty and stop funcitioning.

I don't see how it could be part of the roofing and still function.


04:44AM | 06/16/05
Member Since: 06/15/05
5 lifetime posts
when i had the home built this was an option.The barrier is part of the roof decking it is foil side down.


05:55AM | 06/16/05
Member Since: 04/25/05
1915 lifetime posts
Maybe just a matter of terms, but that "roofing" to be means the exposed finish material.

But what you describe is the decking or sheathing and it sounds like it is installed correctly.

However, I am not usre that I buy the statement it will be no more than 10 degrees above ambianet.

The roof system will get just as hot and it will conductively/convectively heat the air in the attic. But the R-30 insulation (I am assuming that this is on the attic floor) will prevent the heat from that air from being conducted into the house.

But a lot of insulation is transparent to IR heat, but the radiatn barrier is stopping that. So it does help keep the house cooler, but not the attic.

However, I don't have an experience to say for sure. You might want to look at the research from Florida Solar Institue. They have done a large number of research projects on the affects of insulation, radiant barriers, vents, types and colors of roofing materials, etc.


06:06AM | 06/16/05
Member Since: 06/15/05
5 lifetime posts
I called the manufacturer and was told I could expect 10 to fifteen degrees above outside temps.I am leaning toward insufficent venting.


02:14PM | 09/14/15
I am in Central Florida. Radiant barrier works, if it is installed correctly.
1) It should be stapled on the underside of the rafters/trusses, and have an air space between the roof plywood and the radiant barrier. The radiant barrier will then reflect the heat back towards the roof, and it will rise to the top of the roof.
2) You must have proper ventilation. We went to a home where they had hip roofing and installed radiant barrier, but they did NOT install solar powered attic fans. The radiant barrier was actually WORSE, without an attic fan, compared to if they had done nothing. The solar powered attic fans remove the convective heat pressure (think of a pressure cooker, or a convection oven. If the lid is off, or the door of the convection oven is open, it won't cook as quickly). The solar powered attic fans relieve the pressure, create a vortex, and allow the heat pressure to escape.
3) If you have soffits that are vented, they will suck in the outside temperature, under the eaves, and that will create a chimney effect, allowing air flow and venting the heat out of the attic fans.

In summary, you can have attic fans without radiant barrier, but you can't have radiant barrier without attic fans.


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