I live in a 2 story home that I purchased about 5 years ago in Florida that was built about 15 years ago. I was recently in the attic area and noticed it has blown in insulation that has settled to about 4 to 5 inches thick, not much higher than the 2X4 trusses. Would it be worth the investment to blow in another 10" on top of existing insulation? What should the minimum thickness be?
You live in a mild climate area, hot summers 90 degrees, cool winters.
I presume the amount of insulation is OK for the winter?
It's the summer you are concerned about?
The big problem is the amount of heat gained by radiation and the effect of conduction through the wood frame of your home?
Filling the attic with insulation will make a difference.
However, the radient heat landing on the roof, will enter the attic and you need to deal with this by fitting sheets of polystyrene covered with a reflector to bounce this heat back into the sky.
Dealing with the conducted heat is more expensive.
The best solution is a new SIPS roof with a covering that is either silver or white.
To keep your home as cool as possible all walls that are heated by the sun sould be covered with SIPS, where the polystyrene inner is at least five inches thick, preferably eight inches.
Welcome to the forum!
The f.g. you have may be R-11--13 for the thickness: Insulation Fact Sheet
Add your zip code and heating: Insulation Fact Sheet
Compute for radiant or just adding more insulation at a higher density: http://www.ornl.gov/sci/roofs+walls/radiant/rb_tables.html#tablea1
Radiant Barrier Fact Sheet
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