Joist Direction

[DJYork]

If you have an equal bay spacing, which direction is the most economical way to frame your joist (parallel or perpendicular to the roof slope)? Basically, either your joist slope of your joist girder (or beam).

I've heard cases for both, but curious of your thoughts.

 

[msquared48]

Wood rafters with plywood sheathing - normal to the ridge.

Steel purlins with metal roofing - parallel to the ridge.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[BAretired]

With an equal bay spacing, it is most economical to allow joists to follow the slope and let the deck span perpendicular to the slope.

BA

 

[csd72]

I would think it depends on the economies of the supporting structure.

 

[MiketheEngineer]

I've seen it both ways!!

 

[msquared48]

The direction of water flow and type of sheating/roofing will dictate the direction of the rafters.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask