Plywood Direction?

[peciam]

Hello all,

Building a 26 x 26 garage for my son-in-law. Doing it on the weekends, it's a slow go but we're moving along. Trusses are in place and I'm starting the rake and then we will do the plywood for the roof.

Of course he's very impatient and has a friend that gives advise quite often. I don't claim to know everything and don't tell people they are wrong too often. Here's the question: his friend says it's better to put the plywood vertical up the rafters instead of horizontal. I said as long as we stager the joints it shouldn't matter, but I have always laid them horizontal.

Any thoughts? We're using 1/2 ply with trusses 24" on center and clips in between as well.

Thanks

 

[stoveboltgunnut]

I've always been told decking should be installed perpendicular to the trusses.

 

[moserjj]

I've always done it horizontal. I like the fact one sheet fastened to more rafters seems more stable. I have done vertical for wall sheeting but I wouldn't do that again

 

[Bad Hammer]

Plywood sheathing goes horizontal, staggering the joints.
Aluminum "H" clips go between each truss.
Check this link..... http://tamlyn.com/PlywoodClip.html

 

[Gary S]

I've always been told decking should be installed perpendicular to the trusses.

+1^
I always do it perpendicular to the trusses, and offset each row 4' from the adjacent one. It has been a long time since I used plywood. I prefer OSB. The OSB is marked to go perpendicular to the trusses.

 

[rburke65]

I have never seen plywood nailed any other way.....horizontal!

 

[EOC_Jason]

Horizontal... what is his friend thinking?!?!

 

[37ford4dr]

will your budget allow for something more substantial then 1/2 ply? thats probably the minimum for code purposes but over time that will get kind of spongy, can you go bigger? at least to 5/8? and yes horizontal

 

[70redbee]

1/2" plywood or 7/16" OSB laid horizontal with 4' staggered overlap at ends with plywood clips between truss is the only way to do it right. Anyone to tell you to run it with the truss is totally wrong and an idiot.

 

[rsanter]

You want the panel to bridge as many trusses as posable to get the maximum shear strength of the panel and structure
So...horizontal....the way we always see it done

Bob

 

[rlitman]

You want the panel to bridge as many trusses as posable to get the maximum shear strength of the panel and structure
So...horizontal....the way we always see it done

Bob

^^^^^ THIS

And yes, 1/2" gets soft. 5/8" is much better, especially over a 24" span.
Or go with 3/4", and forget the clips altogether.

 

[Big-Foot]

Ditto on the 5/8 or 3/4"

I put them Horizontal and staggered by at least one truss.. Never have 4 corners meet.
Also in heavy snow weight states, I would consider sistering the top of those trusses where two sheets meet as I don't trust the H clips for a lot of snow weight.

 

[BWS]

See if this link works?If so,dig around in here.........

I "think" this is the site?....if it is,have used their technical support in the past on some engineer'd plywood projects.

http://www.apawood.org/level_c.cfm?content=pub_tch_libmain

 

[6768rogues]

The face grain on the plywood goes perpendicular to the trusses. In other words, the long side is perpendicular to the trusses. Plywood is stronger in the long direction; manufacturers and most building codes require it to run across the supports. The friend is just plain wrong. You are wise for questioning the suggestion.
Here in western NY (snow country, using 35 lbs. per square foot snow load) it is standard practice to use 2 foot centers for trusses, 1/2" plywood or 7/16 OSB, and clips between the trusses. If the roof maintained leak free and the attic is properly ventilated, it will last for the life of at least 2 good roofs. The practice has not been around long enough to have experience over more than 40 or 50 years.

 

[mbatarga]

The face grain on the plywood goes perpendicular to the trusses. In other words, the long side is perpendicular to the trusses. Plywood is stronger in the long direction

Exactly - that's why it should be horizontal.

 

[rslaback]

Technically it is only stronger in one direction over another if the plywood has an odd number of plies (which it usually does).

 

[rogsmart]

BWS' link

http://www.apawood.org/level_c.cfm?content=pub_tch_libmain

Will give you a homestudy PHD in plywood technology. I'm only partially kidding, the APA technical library is an amazing resource. Every time I go on it I end up reading a bunch of fascinating stuff totally unrelated to why I went there in the first place.

And for what it's worth... Horizontal.

 

[Big Bad Dad]

The face grain on the plywood goes perpendicular to the trusses. In other words, the long side is perpendicular to the trusses. Plywood is stronger in the long direction; manufacturers and most building codes require it to run across the supports. The friend is just plain wrong. You are wise for questioning the suggestion.
Here in western NY (snow country, using 35 lbs. per square foot snow load) it is standard practice to use 2 foot centers for trusses, 1/2" plywood or 7/16 OSB, and clips between the trusses. If the roof maintained leak free and the attic is properly ventilated, it will last for the life of at least 2 good roofs. The practice has not been around long enough to have experience over more than 40 or 50 years.

This is correct! I did a small building once and laid the plywood wrong. It was weak that way.

 

[Steevo]

So, that's 100% for horizontal and . . . . 0% for any other option.
The friend needs to back off on that one. He is mistaken.

 

[NUTTSGT]

Horizontal. Ask your son's freind where he got his information from, I'm sure I'm not the only one curious.

 

[Kevin54]

Have his friend put on vertical and ask him to walk on it. Then take it off and put it on the right way. I'ma thinkin' his friend just needs to just make beer runs and stay out of construction!!!