Direction of plywood siding?

[DonkeyChicken]

Assuming I use 1/2" CDX for my exterior walls. If one piece of plywood is not big enough to cover a whole side, should I use multiple pieces vertically with a vertical seam between pieces or horizontally with a horizontal seam between pieces? One way must be a little better than the other, what do you all think is better?

 

[50-45-1]

Horizontal leaves a seam that may act like a shelf allowing water to sit.
I think vertical would shed water better.
Are you covering it with something?
Paint or siding of some sort?

 

[EggWalrus]

Horizontal leaves a seam that may act like a shelf allowing water to sit.
I think vertical would shed water better.
Are you covering it with something?
Paint or siding of some sort?

This^^^

 

[3KillerBs]

I agree about using it vertically to allow water to run down rather than sit and be absorbed.

 

[DonkeyChicken]

I plan to use deck stain. I'll stain the edges of the plywood and then stain everything again once it is together.

 

[DobieLover]

I plan to use deck stain. I'll stain the edges of the plywood and then stain everything again once it is together.

I would use a penetrating water repellent sealer instead.

 

[DonkeyChicken]

I meant a stain and sealer, like this one: https://www.behr.com/consumer/produ...um-solid-color-waterproofing-stain-and-sealer

 

[SteveE]

If you are going for a finished look, I might also think about an overall plan for exterior decor, and use that process to locate a vertical strip over the plywood seam.

 

[DonkeyChicken]

Good idea SteveE!

 

[jpalmatier83]

I would look at it from a material utilization standpoint. If it’s more economical, I wouldn’t have a problem putting the seam horizontal. Shingles on your roof have horizontal seams... Even if they’re lapped, if it’s in the right direction, it’s a feature not a bug.