Plywood Span Rating

Question

Plywood Span Rating

dgengineering (Structural)

(OP)

9 Jul 24 03:06

Hello Everyone.

I'm trying to understand what span rating is for a plywood but I don't get the right hand number. For example, if we have 24/0 or let's say, 32/16 I understand the left hand number means the span between joists across the long direction of the plywood but what is the right hand number? I read somewhere that it is the subfloor span or something but still it's not clear to me. I guess I don't much about subfloors. Can anyone explain with diagrams, if possible? Thank you very much in advance

Heaviside1925 (Mechanical) · Answer 1 · 2024-07-09 03:15:59

Hopeful answers your questions.

Link

JAE (Structural) · Answer 2 · 2024-07-09 04:05:55

The first number is the recommended span length for roofs.
The second number is the recommended span length for floors.

dgengineering (Structural) · Answer 3 · 2024-07-09 04:08:00

So if it's 24/0 it means it's only for the roof? or is it for one story maybe? Thanks

JAE (Structural) · Answer 4 · 2024-07-09 14:13:19

I've never used 24/0 but I think you are correct - no span rating for a floor.

lexpatrie (Structural) · Answer 5 · 2024-07-10 04:18:12

Only recognized for the roof, sounds right. I'm a bit flustered right now as my cats just got into a huge fight and I had to intervene.

Tmoose (Mechanical) · Answer 6 · 2024-07-10 16:20:23

so you're starting with 3/8" plywood ?

https://www.apawood.org/Data/Sites/1/documents/pro...

dgengineering (Structural) · Answer 7 · 2024-07-11 06:17:10

also, some thicknesses are not found in the IBC table for some reason. That's something I wanna understand too. Thank you so much for your great answers!

XR250 (Structural) · Answer 8 · 2024-07-16 11:37:30

Also, I believe span ratings are for 2-span continuous minimum. So when the roofer replaces one bay of sheathing, he should be blocking underneath.

Come Join Us!

Posting Guidelines

Plywood Span Rating