# How to attach Roof Sheathing?



## Malcolm (Jun 7, 2007)

sandyman720 said:


> What size and type of screws are best to attach plywood over roof rafters?



8d ring shank nails 2 1/2in. Nail the plywood 6in OC on the edges and 12in OC in the fields.


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## sandyman720 (Mar 6, 2007)

Can screws be used?


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## cibula11 (Jan 6, 2007)

If they are galvanized then yes, but expect to pay A LOT for screws. 

Just a rough estimate, but galvanized screws at $6 a box (1 lb or 50 or so screws). Figure on putting at somewhere around 20 in each piece. So for every sheet you put down you are spending around $10 just on screws. 

Honestly, thinking of the time it takes to put a scew on a drill and get it screwed in, I think it would take longer to screw than to nail. We used a nail gun with 7d nails. Even 8d will drive in with a couple good wacks.


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## Malcolm (Jun 7, 2007)

I would definitely invest in a nail gun if you are replacing all the sheathing on the roof. You'll thank yourself later. I purchased a Dewalt framing nailer for $139.00 at Lowes. They came out with a new model, so I bought the one off the floor. Otherwise, they will only run you around $259.


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## the roofing god (Aug 2, 2007)

nails should be used as suggested,screws do not have anywhere near the "shear" strentgh of nails,I would put 6"nail spacing on all the rafters


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## Clutchcargo (Mar 31, 2007)

Fema recommends screws in high wind areas. I wouldn't think shear strength would matter much for roof sheathing.
www.fema.gov/pdf/rebuild/mat/fema499/hgcc_fact18.pdf


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## joasis (May 28, 2006)

I live in tornado alley, and FEMA has a lot of ideas about things here also. If you want to screw the decking down, by all means, get after it....my first thought was why would you want to? If high winds are a real concern, use screws at the eaves and gables,,,nail the rest. When roof fails, it is "peeled" up, and this, must fail on an edge. What typically happens is the decking doesn't fail, the rafters fail and the decking takes the entire structure with it.


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## the roofing god (Aug 2, 2007)

I also use ring shank nails on all my sheathing,which gives it shear strength & any ,if not more strength holding down than screws,meets DADE county specs,you would go to great expense to match the strength w/galvanised decking screws in comparison,and I think the screws would back up before the ring shank 8d nails ever will---you guys never have a tree hit the house???that`s where shear strength comes into play:wink:


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