I posted the above last year. Since then, I added a layer of unfaced insulation in the attic crawlspace (along the eastern wall of both 2nd floor bedrooms). It was a good, conservative first step, and helped a bit.
I still do not have access to my attic. I bought a window exhaust fan (Air king 9600) and have managed to avoid using AC on a lot of days.
I’m hesitant to add more insulation to the attic floor because:
The heated attic is really a bonus this time of year and in the fall, as it only has to rise to about 60 degrees (outside temp.) and partly sunny to reach 75 degrees on 2nd floor, and 70 on my first. It saves me money in heating costs as my slate heats up like a car dashboard during the day.
My heating costs in winter are not bad at all, suggesting that I’m not losing a lot of heat.
Since slate “vents itself”, can I install a whole house fan to flush out the super-heated air that is in my attic, when I want it out? And will it be OK since it is unvented? I would hate to force the hot air into the living space, if it won’t be forced outside the home.