attic sealing -- how important?

[gsl]

I'm trying to improve the the air quality in my home. I'm thinking a good thing to do would be to seal my house from the attic. Is this necessary? What is the best way to do it? I have rolled fiberglass insulation in the attic. It is pretty much a mess. Would it be worth removing the insulation from the attic, then sealing things like lights and bathroom fans from inside the attic, and then installing new insulation? Who would I hire to do this kind of sealing???

[cxagent]

Hire someone to do a blower door test and determine where your air leaks are. If the big leaks are into the attic (usually are) they can show you how or recommend who in your area will do the work. Assuming they don't do the work themselves.

Try http://www.energyconservatory.com/ for people in your area that do this kind of work.

[cem-bsee]

Be sure that ALL seams & joints of the ductwork, including the airhandler plenums are sealed -- mastic or silicone caulking.

a lot can be done from living area -- remove the plates over the elec devices (outlets, switches, fixtures), seal those boxes to the wall with caulk or spackle. Likewise, seal the HVAC distribution boxes to the floor & ceiling. the plumbing vent pipes usually have big holes around them.

caulk around all wood trim, around windows, above & below baseboard. Best is to first remove trim around windows, then fill with minimum expanding foam the space between window & house framing.