A radiant barrier works best when it is perpendicular to the radiant energy striking it.
Radiant barrier roofing felt.
The hot roof material then radiates its gained heat energy onto the cooler attic surfaces including the air ducts and the attic floor.
If you take radiant barrier foil and sandwich it between the shingles and roof felt you have now created one solid assembly.
You are getting a new roof so why not scrape off the shingles put down roofing felt then radiant barrier.
Because a radiant barrier needs an air space on at least one side installing it directly below felt and shingles will not allow the radiant barrier to block any radiant heat.
This is one example why we cook with aluminum cookware.
For example if you install a radiant barrier on top of roof decking between the felt paper and asphalt shingles it will not provide any benefits as the radiant heat would be transferred through the shingles through the felt to the radiant barrier and through the roof decking into the attic space see image below.
Radiant barrier under shingles scams bad information at first it sounds reasonable.
Here is how to install radiant barrier in metal and tile roofing products.
Hello experts my experience in roofing is 0 if 100 is not possible recently we had some hail storm i need to replace my roof.
One roofer offered me to install polaralum as radient barrier over the deck for a aditional cost of 1600 and according to the roofer i can get the energy tax credit.
It conducts heat very well which is good for cooking but not so good for living spaces.
Instead the heat from the shingles and felt will conduct all the way through the barrier into the attic and eventually in the living spaces.
I m not sure why you would use a 50lb felt with radiant barrier attached unless you were installing under a metal or tile roof.