Thank you both. A few more Q's...

1.I need to go back up & measure the gable vents but they look pretty small. Also, when I first went up there they were completely blocked with dirt. I have since cleared them with a wisk brush & vacuum.
**Should I replace them with different vents?

2. If they get blocked again I would obviously need to access them but, once I have all that insulation in place that will be nearly impossible.
Do you recommend I go to the trouble of building some sort of platform walkway over the insulation space? Other thoughts about access after the fact? (I'm trying to plan ahead but could still need to get up there in future for electrical, etc.

3. Since the fan is already cut into the roof, could I not count that opening as a passive roof vent in the event my gable vents are too small? I hate the thought of cutting any more vents into the roof as I may end up with leaks which I don't have now. Would you think cutting just 2 soffit vents, 1 on each side of the attic about midway down the length of the house would serve the same purpose?

4. I have seen Mr. Hetzel recommend removing old insulation in the past & I am curious as to the thought process each of you has regarding the pros & cons of removal.

Thanks again,
Sheila

1. I don't think I'd go to the trouble of replacing the vents. There haven't been any problems up to now. If you had to clean them again, you could use a couple of temporary boards for access.

2. See #1.

3. The inactive fan doesn't hurt, and could help ventilation a little. I don't think soffitt vents would add anything of value.

4. The only reason I suggested taking out the existing insulation was that, if it were my house, I'd like all that dirt and dust out of the house. There is no harm in leaving it in.

In any house we have ever remodelled, as long as old insulation is not wet or has evidence of ever being wet, then we have not removed it. No matter how old it is, it still has an R value that will be added to the additional insulation you may add. Also anyone who has ever removed old blown in insulation from an attic will tell you that they will probably never do it again, too much dust and mess for what it's worth.