How impressive is a radiant warmth blocker paint to the underside of a roof? I have a two storied house but singular one air conditioner. The...

I have a two storied house but singular one air conditioner. The thermostat is located on the first floor. During summer the rooms upstairs really take hot during the after noon hours and is almost impossible to stay upstairs. Can a radiant warmth blocker paint to the underside of the roof be of any help. How significant (temperature reduction surrounded by the attic) is this method?
How do I loosen really rusty bolts on...
Answers:    They say that radiant cordon paint really works...but for the life of me I can't see how a covering of silver paint on the underside of your roof can do any good at adjectives...except make money for the company that sprays it on.

A philosophical layer of blown within insulation is you best investment....plus add a apposite attic ventilation system....which could be gable vent as well as power roof vent....and maybe even some lower than eve vents that allow the cooler nouns to enter at lower part and hotter nouns to escape up high through the power vent.