Roof repair alternatives

I am considering alternatives re how to repair an old, leaking roof.
The roof has a shallow pitch (4 in 12?) and a single layer of asphalt shingles in bad condition. They are not curling much but they are badly weathered and missing many edges. And there are plenty of leaks. I don't know how long the roof has been leaking; it leaked already when we bought the house last year. (We factored the cost of a new roof into the purchase price.)
Part of the roof is over an attic. Under the shingles is tar paper over sheathing. From inside the attic (crawl space) in many spots the sheathing is cracked or broken. The roof has an 18" overhang and neither soffits nor ridge are vented. The attic has gable ends with vents but at one end the vent is covered with siding.
Another part of the roof is over an addition with a ceiling of exposed rafters and tongue&groove boards. I don't know what lies between the asphalt shingles and the ceiling. Probably not much, because the addition gets very cold in winter and hot in summer.
The house is in very sunny and dry New Mexico at 7000' elevation (so nights are cold). It has no AC nor a swamp cooler but is cool in summer thanks to deciduous trees that overhang the west side of the house (blocking afternoon sun) and good cross ventilation. The climate is "high desert", so heavy snows, monsoon rains, and significant hail storms are normal.
A recommended local roofer proposes to strip the old shingles then install new shingles. I anticipate once the old shingles are off I will hear that the sheathing needs repairs and the roof needs to be vented. Should I go with stripping the old shingles? Should I plan to replace the sheathing?
    Una
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On Dec 9, 1:03�pm, snipped-for-privacy@att.net (Una) wrote:

yeah i would if you plan on living there very long, and even if you dont it will be a big issue at resale.
better ventilation longer life and 2 layers isnt a good idea, its a cheap out approach.
besides do it right do it once and forget about it...........
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On Dec 9, 11:03 am, snipped-for-privacy@att.net (Una) wrote:

You anticipate correctly. Tear-off, repair/replace decking and add ventilation. Maybe insulate where possible? Tom
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On Sun, 09 Dec 2007 18:03:03 GMT, snipped-for-privacy@att.net (Una) wrote:

Remove shingles and tar paper, do necessary repairs, add vents. Should last 20 years, maybe more. Layering over old shingles might over burden your roof when it needs that strength to hold the snow.
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On Sun, 09 Dec 2007 18:03:03 +0000, Una wrote:

FEMA's approach has always been a large blue tarp.
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Una one added part. Before you contract, find out from the various folks how much it will cost per panel that may have to be replaced. Thats the hidden 'gotcha' and there can be HUGE differences but once you start, you have no choice but the follow through. The job has to be finished pretty quick once started.
You know you have leaks, so you know you have damage. Factor that in, and the earlier fixed, the cheaper it is.
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Yup. My thought exactly. I am rather disturbed that the proposal did not address this likely contingency.
The main roof has sheathing boards now. Can they be mixed with plywood or OSB underlayment or will I need to stick with boards?

I hear you. Deferred maintenance usually is *expensive* maintenance, plus there is the added aggro factor of living with the problem. I do not like surprise puddles on my kitchen floor. Nor falling ceilings nor rot in the walls...
    Una
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"Una" wrote

One thing we found out, fortunately *before* we made the mistake, is why some of the 'cheaper bidders' are cheaper. They price out just the tile etc removal and do not tell you the rest.
Once they've pulled it all off, you have to pay whatever they cost as you cant wait a month or more like that, for a better priced fellow to finish it off.
I do not recall the exact prices but our job when like this:
1,500 remove tile and put new, 70$ new wood panels (many as needed, 70$ each).
Other fellow was 750$ but on checking, panel replacement was a whopping 250$ each. Can you guess the difference?
Did our fellow get his money back for our job? Yes, and he's now the choice of everyone in my neighborhood who doesnt have major structural issues because they 'used the other guy'. My neighbors have rotting beams at the roof and attic floor because of shoddy work. It's costing them LOADS.

Sorry, I do not know. Thats one only a real roofer can answer. Mine was plywood to start with.

Rot in the walls can be devistating. You can basically lose your house but still owe the bank over that one. Insurance may not help at all.
Just please, do not get in the situation of one of my neighbors. He's got to have the entire roof structure removed,many of the ceiling joists in the floor of the attic, and a new one put on. He's owned the house for 20 years now and it's going to cost him well over 30,000$.
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Cshenk wrote:

stated in the bid, along with start and completion times. Ridge vents should not be costly. There is a formula for attic ventillation. I believe it is 1 sq ft roof vent per 300 sq ft of attic _floor_ area. Warm, dry weather is best time.
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