I live in Houston, TX, and our house is a 1 1/2 story, 1900 sq. ft. We have 2 issues: 1 - the top floor sometimes has a hard time getting down to temperature on hot days, and 2 - high humidity is a problem throughout the house - it just doesn't feel as good as we'd like, until we turn on the a/c.
The a/c technician looked in our attic, and said we desperately need insulation up there, so I got a quote on blown celbar (cellulose).
Our downstairs has no subfloor, and no vapor barrier. The insulation under the house is very spotty - some is there, some isn't. We have little to no insulation to speak of in the walls, either (this is an old house.
With our upstairs a/c system, the condenser is outside, and the blower is in the attic. If we're trying to get the system to work less hard, my thought was to get the temperature of the attic a bit cooler, maybe with a radiant barrier. The air ducts are already insulated.
I guess my questions are:
will the insulation help keep out humidity?
Should I buy a good dehumidifier, or should I have insulation installed under the house? The insulation company came to give me a quote, and recommended blown celbar - she said it would act as a vapor barrier, as well as insulation.
Also, would the insulation in the attic result in a lower temperature in the house, or should I pursue a radiant barrier first, if at all?
Any thoughts? Thanks!