Attic Insulation Help

Discussion in 'Insulation and Radiant Barriers' started by charbear, Apr 28, 2011.

  1. Apr 28, 2011 #1




    New Member

    Apr 28, 2011
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    I have a two story (maybe 1 1/2 since the front half of the house has a 2nd story while the back half rooms have vaulted ceilings with no 2nd floor on top of them. The upstairs ductwork has always been somewhat inadequate in my opinion. Relatively little air flow comes out compared to the downstairs vents. We try and even this out by closing some downstairs vents. We are in Central FL and it gets HOT for a long time. I am thinking about blowing in more insulation in the attic. Questions:

    I have included links to pics if it would help. The insulation is pink blown in and is mostly abut 8", though some spots are closer to 6 and even 4 in a few places. Do I need more and how much?

    Also, on the vaulted ceiling area, there is no insulation. I assume this would be so as to not block the airflow as it comes up from the downstairs rooms, passing above the vaulted ceilings and into the attic to escape. The pics show a bit of the upstairs insulation and also show a "hole" which is what leads up from above the downstairs ceilings. Was the supposed to be insulation in there or is this truly to be "uninsulated".

    In the "drawing" at the end, the 4 levels are the downstairs floor, downstairs ceiling on front side of house, the vaulted ceiling in red, ceiling of 2nd floor (attic above).


    insulation Photo Gallery by charbear at
  2. May 5, 2011 #2




    Well-Known Member

    Apr 15, 2010
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    There is no effective insulation in your home.

    There are various ways you can solve the

    problem, each has a cost, but doing the job

    properly will make your home much nicer to

    live in and it will be a lot cheaper to run.

    How long do you intend to live there?

    The most effective way to insulate your

    home from the sun, it to take the roof off

    and cover the rafters with a sandwich of

    oriented board and polystyrene and then

    put the roof back on.

    (You need at least 5 inches of polystyrene

    in the sandwich....8 inches is better)

    This system is called SIP's.

    Done properly this isolates your home from

    the effects of the sun. The oriented board

    sandwich is fixed to avoid any heat bridges.

    Most of the heat gets into your home by

    conduction, some by radiation and some by


    Repeat the system over the walls and you

    have one cool home.

    This solution is the best you can get and

    really the only way to keep your vaulted

    ceilings looking great and keeping you cool.

    Take a look at the duct work, is it insulated

    and air tight?

    The fact that it works at all in the heat is

    some kind of miracle. It needs at least 4

    inches of sprayed foam covering all sides,

    again 8 inches will do a better job.

    If the above proposal is too expensive, then

    fitting sheets of polystyrene cut to size

    between the rafters and below the rafters

    will provide a great improvement. Use one

    inch and two inch thick sheets, cut them

    with a knife to a push tight fit.

    After doing the roof, fill the spaces between

    the joists in the same way. For the best

    result pull the ceilings down and fit three

    inches of polystyrene sheet across the

    ceilings below the joists to stop the

    conducted heat coming through the joists

    into the rooms.

    This system will spoil the look of your

    vaulted ceiling but, you can create another

    fake ceiling below your existing one.

    Then use the same system in the outside


    Cellulose and fiberglass are rubbish and

    cannot keep out the heat, they are both

    conductors of heat, remove the so called

    insulation you have and dump it.
  3. May 6, 2011 #3




    Well-Known Member

    Jan 8, 2011
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