Attic Insulation Help

[charbear]

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).

Thanks!

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[pushkins]

There are no links posted.
Current code dictates min. insulation of R30 in ceilings (R49 in some areas) on the planning block is R49 nationwide. At 6" thick you currently have about R19 a long way from min. code and without doubt costs you money with heat transference. You can rent a blower from Lowes or HD often if you buy enough insulation you get the machine free. The trick is going to be that you must make sure you don't block airflow access from the soffits (between the rafters) to do that you need to use baffels also available in the insulation aisle ($1/piece) these are foam and fit between the rafters down at the lowest point towards the soffits and stop insulation blocking the airway.
Cathedral ceilings are a whole new beast, should always be insulated as well and are often difficult to insulate, again baffels must be used to stop insulation blocking up any airway from soffit to over the insulation and on up to ridge vents etc...most times it's best to use fiber insulation (rolls) as it holds together on the slope.
A tremendous amount of heat is lost in cooler months in cathedral ceilings that are uninsulated and any non insulated ceiling allows all attic heat into the house. Drywall has an R value of .45 = basically nothing.