Roof Deck Replacement

We are looking to have a roof replaced on a home we are in the process of buying. The house is currently on its 2nd roof..ours will make the third roof put on. The decking is 30 year 1/2" plywood not sure if its CDX but it definitely is not OSB. I had several contractors come out and give me estimates but I had one come out and tell me that I should have the decking replaced. He said that with another tear off and replacement I will have a much weaker decking and that the roof will more than likely sag. What he said made much more sense but on the other hand I had another contractor say that I may need some wood replacement but not the whole decking. Does anyone have any thoughts about this. Should the decking be replaced? After all it is a 30 year roof and this will make the 3rd roof placed on it. Keep in mind I'm not looking to spend anymore money than necessary but I would rather pay now then later.
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The guy that said 'replace it all' must have a boat payment due. Did he crawl around in the attic and inspect all the underside, or do his inspection from the ground? The other contractor is right- a 30 year old deck is likely to need the odd mushy spot repaired (like around chimney, and along eaves where ice dams happen), but most of the deck is probably fine. Like any rehab work, you don't know for sure until you open it up. Strip it all to bare wood, replace mushy spots as needed (including rafter repairs underneath, if needed), replace ALL the flashing and drip edge, upgrade attic venting if below current standards, use the rubber membrane on the bottom 3 feet, and your new 30 year roof should last 30 years. Like most home repairs, the prep work is half the project. Plan on being there when they do the work, so you can make sure they don't cut corners. A quality roofer will have no problem with the owner watching, as long as they don't present a safety hazard to his crew.
aem sends....
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Have you considered a metal roof as an option? It will strengthen your roof up as well as protect it from the elements. Today there is much more variety in styles and patternss than there used to be. I have seen roofs that look like slate, or shingles and upon closer inspection are metal. Cost where I am is comparitive. And you never have to put on another roof again. Installation is alto a DIY project, this allows you to see the roof deck first hand and replace anything YOU see that needs it. Of course shingles are also DIY but it is a much more labor intansive process than roofing with metal.
Depeding on how brave you feel, take some time and tools up to the roof and do a few spot checks yourself. Just my 1 cent (after tax) worth. Kirk
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I am a Firefighter and I can tell you first hand that I would rather walk on a metal roof over a shingled one anyday. Fire can eat away the joists below the sheathing, leaving it visably ok from the top but impossible to walk on with a shingled roof. Metal on the otherhand only slightly bends.
Try this test. Get a sheet of plywood and cut a 1 foot hold in the center. Shingle it and step where the hole was. It doesn't take a genius to figure out that your foot will go thru the hole. Cover same hole with metal and step on it. Your foot will not penetrate the hole.
One could put a metal roof over rotted sheathing and never give it another thought. I would not want to do the same if I were shingling it.
Thats how I feel, no-one said you had to agree with me. Cheers Kirk
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On 26 Jun 2003 18:53:44 -0700, snipped-for-privacy@hotmail.com (Peregrine) wrote:

You can't decide on replacing decking until the roof has been stripped. Especially if he didn't know what material was under it. There's no reason to replace sound decking, and if there haven't been any serious leaks the deck is likely pretty solid.
Most estimates will give you a price for strip off, a price for roofing materials, a price for labor and a price for deck repairs. The repairs usually are a per square foot or per sheet of decking type of estimate, and are never firm. No reputable roofer can tell you what will be needed until the tear off.
The real key in your situation though is that several contractors came out, and only one told you he had to replace the deck.
Jeff
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I just finished doing a 30 year roof replacement. Out of 9 squares, I replaced 1 full square of sheathing; no rafter repair. The majority of the roof was in fine shape. I attribute at least part of this to proper ventilation. An earlier thread in this group helped me to discover that an odd looking ridge on the roof was actually a hand built ventilation system (thanks Steve, for the off group help!). Seems to have done it's job, though I'm also installing a thermostat fan vent.
clyde
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