Advice on attic insulation/ventilation improvements

We recently purchased a ~50 years old house in the SF bay area. The roof is >20 years old, wood shake, we expect to replace it in a couple years. There is minimal attic ventilation: a few holes drilled in the eaves and gables. There is also minimal insulation: 2-3 inches of loose cellulose. I'd like to do what I can to improve these for energy efficiency and to keep the house cooler in summer.
I've talked to two roofers; one suggested installing additional inlet vents between the rafters (we have open eaves), plus a couple outlet turbines; the other said the shake roof will breathe so he didn't see the point in doing anything now. Any opinions on who is right?
I'd like to bump up the insulation to R30. We have a few old recessed can lights, I can't easily determine if they are IC rated hence they probably are not. Would it be wise for me to replace these with IC rated cans, or just ensure that the insulation doesn't contact them?
For insulation material, we've gotten quotes for blown fiberglass. Once you've installed a thick layer of this, it seems to me that attic access is going to be a huge pain in the ass, right? I'm thinking that we should do any other attic work -- like installing bathroom vents -- first, for this reason. Or, is it not a big deal to move the stuff around after it is in place?
It seems to me that the insulation is the first priority; ventilation won't prolong the life of the roof, and the insulation will make the biggest difference in keeping the house warm/cool. Am I right? On the other hand, if it will be much easier to do the eave vents before the insulation is installed, that would be a good reason to do that now, if we'll need them later (say if we get a composite roof).
-- Dave
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Dave -
FWIW, here's my opinion on your problem. First of all, I have gone around this block twice (with 2 homes) and it is no fun.
I think the first roofer is right.
On the venting, I would recommend a minimum of adding "ridge vents" near the peak of your roof and inlet vents. If it were me, I would go all the way and also add an attic fan (or fans, depending on the size of your house) and additional inlet vents. If you have A/C, your attic fan will save more electricity on your A/C than you spend on running the attic fans themselves. Your roof will last longer, too. Properly vented (with passive vents) your attic will hit about 140F on a super hot day. With attic fan, you can get this down to about 110F.
I agree that you need R30 in the ceiling and that it should be the first priority. Installing it is literally a pain. Get some sheets of plywood that you can lay across your rafters. This will ease the pain. Keep clear of your light cans by 1 foot. Also, make sure that you don't block any of your eave vents.
If at all possible, do your insulation when the roof is off. That way, there is a lot more room to move, you can stand up, rather than crawling through fiberglass, and you will have better ventilation so you won't be wallowing in fiberglass dust.
If you have to do the job piecemeal, then get a jumpsuit and tape the wrists and ankles shut. Wear gloves. Wear a respirator. You are going to be wallowing in fiberglass and swimming in fiberglass dust. Installing is a 2 person job. Once you have crawled to an area, you need a helper to "feed" you strips of insulation.
Good luck.
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The venting fan issue has been raised before in this group. Many differing opinions (of course) . Did it help after you installed one? How did you determine placement, sizing, etc

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I fully intend to install ridge vents when we replace the roof, but the current one has a couple years of life in it. The turbines would be a short term and fairly inexpensive fix in the meantime. I'm not sure what we'd do with them after we replace the roof with a better system.
-- Dave
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snipped-for-privacy@sonic.net wrote:

Any opinions on replacing the existing cans with IC rated ones? Not worth the trouble for our mild California climate, or better to just do it now?
-- Dave
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