The heat that would normally be absorbed by the insulation is now being bounced back to the roof deck and causing the roof to emit more heat upward rather than both upward and downward.
Roof insulation radiant barrier.
A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic.
Radiantguard radiant barrier foil insulation installed in an attics can reduce attic temperatures by up to 30 degrees when stapled with a staple gun to the underside of roof rafters by reflecting up to 97 of the radiant heat that strikes its surface thereby reducing heat transfer from the attic to living spaces resulting in lower utility bills.
This method also reduces the heat subject to attic mounted ac duct work thereby allowing them to work more efficiently.
Installing a radiant barrier underneath the roof will cause the roof temperature to increase by a few degrees usually 2 10º.
The hot roof material then radiates its gained heat energy onto the cooler attic surfaces including the air ducts and the attic floor.
By reducing the amount of radiant heat reaching the insulation in your attic the insulation remains cooler and is able to keep your home more comfortable.
The list of uses includes crawl space radiant floor attic and walls.
Radiant barriers are utilized to reduce summer heat gain in attics and help to improve the efficiency of green building envelopes.
A radiant barrier can be effective with an asphalt shingle roof only when installed inside the attic either to the underside of the roof decking or to the underside of the roof rafters.
In these attic space applications there is an air space below the radiant barrier.
However radiant barriers can also be installed in other ways such as having it infused with your roof decking or underneath tiles.
Reflectix insulation has over 20 energy saving applications for reflectix insulation has over 20 energy saving applications for around the home.
For a picture of this in action you can check out the product listing on amazon.
A radiant barrier is designed to increase the effectiveness of your thermal envelope.
A radiant barrier is typically stapled to the bottom truss chords against the deck sheathing.
A radiant barrier can lower heat transfer from attics to the building below keep the attic space cooler and lower cooling costs by up to 17 in warmer climates.
A radiant barrier works best when it is perpendicular to the radiant energy striking it.
It is meant to supplement insulation not replace it.