How many screws per board?

[UpToNoGood]

I am building a 20x20 garage this summer and I am in the planning/material gathering stage.
The outer walls will be ¾ plywood running long to cover more studs. Each board will cover 7 studs 16 on center. So my question is how many screws per stud? I was thinking 5 per stud each screw being 2 long. The boards will be staggered like bricks.

 

[s219]

Plywood I generally fasten down on with 12-16" spacing between fasteners.

 

[ultrarunner]

Code required me to nail 8d nails 4" on center around the perimeter and 12" on center in the field... screws not allowed.

 

[byronlj]

Ultrarunner is correct. My inspectors will even frown if we go as much as 12" in the field.
Dave

 

[NoTrespassing]

What is the thinking behind screws not being allowed by code? Is it engineering or does the code need to be updated to allow them?

Kevin

 

[blueriver]

I'm curious why your running the plywood that way?

 

[B7510HSD]

What is the thinking behind screws not being allowed by code? Is it engineering or does the code need to be updated to allow them?

Kevin

I was told nails are stronger than screws?

 

[GGB]

I was told code may require nails because they have better shear strength than screws.

 

[Papasmirf]

The plywood is ran perpendicular to the framing for strength. This locks the framing together and helps to prevent "racking" of the walls during high winds, snow loads, etc.

 

[LD1]

I was told nails are stronger than screws?

It is all in how you define "stronger".

Nails are softer, will bend instead of breaking/failing, and usually are better for shear loads.

Screws are much harder, and usually take more effort to pull out.

So it all depends on the application. I would do what code requires in the area.

But I am sure hundreds are built with screws, and hundreds are built with nails, and neither will fail if used and installed properly.

 

[Papasmirf]

For me the screw is the choice I'll make most of the time.

 

[blueriver]

The plywood is ran perpendicular to the framing for strength. This locks the framing together and helps to prevent "racking" of the walls during high winds, snow loads, etc.

I thought plywood vertical not horizontal was stronger .. Imagine that!!

 

[Papasmirf]

The only time I've framed plywood vertical is when us on the corners only that will just strengthen the corners. And generally the ready of the structure is covered with blackboard.

 

[Papasmirf]

The only time I've framed plywood vertical is when used on the corners only that will just strengthen the corners. And generally the rest of the structure is covered with blackboard.

my present home is covered on top of the studs 7/16 wafer board ran horizontal.

 

[UpToNoGood]

Here is a drawing of how the plywood is to be placed. Like others have said running the boards horizontally allows each board to be screwed in to more boards reducing the change of racking. I am aware of the nail vs screw debate and in this application the boards won't be holding a load so I am not worried about them shearing.

 

[byronlj]

Those a shear walls. The reason to run vertical sheets is to attach the bottom and top plates with one piece whenever possible. Nails are required for shear walls because screws will snap vs. nails bending. Inspectors take shear walls very seriously. They look at materials, fasteners, orientation, door window openings, and wall locations.
Dave

 

[ultrarunner]

I was told code may require nails because they have better shear strength than screws.

This is the reason given by my local building department... the nailing schedule provides a superior shear wall.

Apparantly after the big Loma Prieta Earthquake incidents of screw failure were found because most screws are hardened and brittle compared to nails.

 

[UpToNoGood]

Those a shear walls. The reason to run vertical sheets is to attach the bottom and top plates with one piece whenever possible. Nails are required for shear walls because screws will snap vs. nails bending. Inspectors take shear walls very seriously. They look at materials, fasteners, orientation, door window openings, and wall locations.
Dave

I don't have a problem changing from screws to nails. As for running the plywood vertical they wouldn't reach the top so I am running them horizontally.

 

[deepNdirt]

You may consider purlin blocks between the studs at the location of the joint of each sheet, and cut in some diagonal bracing in each of the corners,
As it might seem the more the better when it comes to nailing, there is one thing I learn the hard way, Too large and too many of either nails/screws can split a stud wide open, even an inspectors don't realize this possibility, only someone with common since will know this, If you put nails ever 4-6 inches in the sheathing, and then come back and install siding onto the wall again adding nails ever 6-7 inches you could risk splitting the stud,
Spacing of nails @ 8"-10" will be fine, and using a ring nail will hold as good as a screw and with less risk of splitting the stud, Note if you use a nail gun be sure to regulate the air pressure as to not sink the nail through the sheathing,

 

[tallyho8]

Lowes and Menards and other stores sell 4x10' plywood but it usually has to be special ordered.