# need advise on a new roof



## grouse9392 (Oct 10, 2010)

Hey guys I'd appreciate some feedback.

The current roof on my 1954 rambler is in need of replacing. I don't have any leaks but the current roof decking which is only 3/8 plywood is delaminating and pretty spongy when walking across. I am planning to have a complete tear off done and all decking replaced. 

The bids that I have received are all based on 1/2 CDX. My rafters are 24" OC. I live in Northern Virginia and we don't get alot of snow fall. 

My questions are based on wanting a good solid roof:

Is the 1/2" CDX preferred or should I go with 5/8"? 

Is there any significant difference in the grades of plywood for roofing and if so which is preferred.

If you were putting the roof on your house what would you lay down as the decking?

Any additional feedback regarding what I should be asking the roofer is appreciated as well.

Thanks in advance for your time and assistance.


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## acc (Nov 17, 2009)

A complete tear off is definitly the way you should go. 1/2" roof sheating with age clips or 16/32" T&G plywood would be plenty strong, but you should check your local building codes first. 5/8" plyw would definitly be stronger but not necessary.


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## Grumpy (Oct 29, 2008)

A complete tear off is the only way to go if you are trying to fix the plywood. 1/2" CDX will likely meet code, however you have the check the span rating on the plywood its' self. Is the sheet rated for 24" span? Also there are two types of 1/2". When I call my lumber yard, they ask do I want 1/2" 3 ply or 4 ply. I always opt for the 4 ply (unless I am doing a resheat over spaced decking.)

I was just telling a buddy the other day that if I were building a house for me I would want 5/8" plywood or thicker. Also I don't want to start an argument, but OSB and CDX are not the same, I would not use OSB on my home if it were free... well maybe if it were free. 1/2" really is standard though and if you were my customer, more than likely what I would be recommending (not seeing the house or knowing any details.)


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## danielbyrne (Oct 7, 2010)

*5/8" and OSB redecked*

Go with 5/8" inch if your budget can afford it. The 24" span is a hallmark of a cheap track home. You will get sagging in between the rafters after just a few years. The 5/8" will reduce that likelihood. Also I prefer OSB over plywood. Plywood delaminates when wet and splinters when you nail it. OSB is tough, much tougher then regular plywood, more water resistant, and it's cheaper.


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## Grumpy (Oct 29, 2008)

I disagree with everything daniel said in regards to plywood vs osb. i said I didn't want to start an argument, but I guess I did. Plywood willd elaminate when wet but it takes alot of getting wet to do that. Both plywood and OBS will swell when wet but osb will not go back to shape, CDX will. This means buckling at the seams in the plywood which leads to an ugly roof and potential blow offs. IMO OSB is not at all an exterior product, only used on the exterior cheaply built homes in my area. People use it because it's cheap.


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## ecenur (Oct 17, 2010)

grouse9392 said:


> Hey guys I'd appreciate some feedback.
> 
> The current roof on my 1954 rambler is in need of replacing. I don't have any leaks but the current roof decking which is only 3/8 plywood is delaminating and pretty spongy when walking across. I am planning to have a complete tear off done and all decking replaced.
> 
> ...


The grades of plywood for roofing are, "A,B,C,D,X" I honestly think that there is not much a difference in the quality however, the better the grade, the better the surface. The grade you choose is up to you, their all the same thing for instance, the grade AA is smoother & it has no knots. It really depends on what your looking for, if you just need something to fix your roof or cover it up go for something simple.


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## Ridgewalker (Aug 12, 2010)

I agree with Grumpy CDX is the way to go 1/2" 4 ply standard is the norm. If you can afford it 5/8 CDX is better. Use plywood clip on either 1/2" or 5/8". Out here when we have roofs with 3/8" by code we need to overlay 1/2" Plywood on top of the 3/8" and really stiffens things up just like having 5/8" plywood.
hope it helps.


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## grouse9392 (Oct 10, 2010)

Thanks guys.

I've been leaning towards the 5/8 just out of gut feeling so will go that way.

Any opinions on replacing the existing cooper flashing around the chimney. Go with cooper (what gauge) or other flashing material?


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## FerrisHI (Oct 20, 2010)

I didn't even know there was an arguement to be made between CDX and OSB...I have always thought CDX is way better...I would put 5/8 on the 24" rafters not that much difference in price when your talking about a full tear off job...my 2 cents


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## blageurt (Dec 15, 2009)

If it was my house I would go with 5/8 exterior T&G plywood sheathing . I , like Grumpy, see way too many New homes built here built with OSB crap.... I would not use OSB on a Doghouse.... I would also do 2 passes Ice/H20 shield and Full paper /Armour Guard/Grace underlay over the entire deck, Then I would install a 30 plus year laminated Shingle ( Timberline/ Landmark or similar) and a continious Ridge Vent and call it a day... Like I said , if it was mine


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