Shed floor joist direction

[FordTruckWench]

Getting back to a much delayed project...

An 8' x 16' *cough* 15' shed. The ground is sloping, and I want the shed floor raised up a bit - possibly as much as 4' at one corner. Thus there is plenty of air space under the floor, plenty of vertical clearance for all framing. Consider the wood floor to be temporary, to be replaced in the far future with a masonry foundation and slab floor.

The long time plan has been to have two 16' 4x6 beams supported on posts and pier blocks. Then nine 8' 4x6 joists topped by 16' 2x6 T&G decking. Based on current prices for T&G, I'll instead use plywood with the grain in the 16' direction. Lets call this the "ladder" configuration.

Should I flip the joist direction? In this configuration, there would be three "bents" topped with 8' 4x6 beams. Then five 16' 4x6 joists topped by plywood with the grain in the 8' direction. Call this the "(railroad) trestle" configuration.

Both configurations use the same total length of 4x6 material. Both have 8' joist spans. Both have 4' beam spans between piers. The trestle configuration needs one fewer pier block (9 vs. 10).

 

[The Tool Tyrant]

32 years of framing experience speaking here. Assuming 'normal' shed storage, I would go with your "ladder" configuration BUT, If using 4X6 beams, I would break the 15' span down to 5' (4 posts) and use 2x6 joist @ 16"o/c rather than 4x6 @ 24" o/c. Use 3/4" T&G ply for flooring.
If it were mine, I'd go with 4X8 beams and 2X8 joist...but I tend to overbuild.

 

[firebirdparts]

I agree with the tool tyrant. 4 by 6 joists just sounds like a waste of material. Under no circumstances would I flip the joist direction.

 

[FordTruckWench]

Assuming 'normal' shed storage,

Everything in it will be carried through the person door, i.e. no wheeled vehicles at this point.

I would go with your "ladder" configuration BUT, If using 4X6 beams, I would break the 15' span down to 5' (4 posts) and use 2x6 joist @ 16"o/c rather than 4x6 @ 24" o/c.

Plan is five posts on the 15'/16' span. That way there is a post under joists #1, #3, #5, #7, and #9. Reason for 4x joists is that they won't roll over and thus I don't need rim joists across the ends.

BTW, the structure will be 16' long. A future doorway at one end will be recessed one foot so that the interior is 8x15, i.e. the 120 sq ft. no-permit limit.

Use 3/4" T&G ply for flooring.

Plan is 1 1/8" T&G ply - in lieu of the too expensive 2x6 T&G.

 

[FordTruckWench]

4 by 6 joists just sounds like a waste of material.

Going to 2x6 joists @ 16" would need four more, plus rim joists. 72 linear feet of 4x6, versus 136 linear feet of 2x6. If we look at nominal dimensions, that's almost the same amount of lumber.

Also, in the ladder configuration I'd install earthquake holddowns and bolt through the floor to joists #1, #3, #7, and #9. That'll turn the walls into structural members.

Under no circumstances would I flip the joist direction.

OK, now that's an answer!

 

[The Tool Tyrant]

First, you'd be much better off to use joist hangers to attach the joist to the beams as this allows the plywood to nail to both, the floor joist AND the beams creating a diaphragm floor system (meaning it can't rack out of square)
Second, you would need to either block between the 4X6 or use a rim board if you bear the joist on top of the beams.
2X6 @ 16" o/c with 3/4" T&G is a better choice than 4X6 @ 24" o/c with 1-1/8" T&G and probably cheaper too.

 

[quickfarms]

Recessing the door 1’ does not change the 16’ dimension to 15’ unless the entire wall is recessed.

square footage is based on the exterior dimensions not interior.

 

[FordTruckWench]

Recessing the door 1’ does not change the 16’ dimension to 15’ unless the entire wall is recessed.

square footage is based on the exterior dimensions not interior.

My county's code explicitly says that square footage is interior space plus wall thickness. And an entire end wall will be recessed. It will be the walls "around the corner" that continue on as buttresses.

 

[billconner]

Did I miss something? isn't exterior dimensions same as interior plus wall thickness?

Definitely set top of beams same as top of joists and attach plywood to both. I'd get away with 6 piers, 3 on each long side. Without looking probably makes the beams a double 2x12. I'd anchor those to concrete piers with a metal bracket - like Simpson - and hang 2x8 joists 24 on center. All to simple and direct.

Studs align with joists and rafters with studs and single top plate and 2 stud corners.

 

[The Tool Tyrant]

Also, in the ladder configuration I'd install earthquake holddowns and bolt through the floor to joists #1, #3, #7, and #9. That'll turn the walls into structural members.

If you're going as far as including hold downs for seismic control, you'd be money ahead to pour continuous footings and stem wall, then you can include the proper Simpson SSTB anchor bolts in the footing, then frame stem walls to floor height OR do masonry walls to floor height. Either way, you'll be able to have a continuous load path from roof to footing to satisfy your seismic requirement.

 

[nadogail]

Tool Tyrants 32 years of framing is one hell of a credential, do'nt waste your time and money trying to Micky Mouse the job, a cheap "Slide Under The RADAR" job will cost you when it fails or you get caught on some overlooked detail. Not every inspector is lazy, some really care about safe buildings.

 

[FordTruckWench]

If you're going as far as including hold downs for seismic control, you'd be money ahead to pour continuous footings and stem wall, then you can include the proper Simpson SSTB anchor bolts in the footing, then frame stem walls to floor height OR do masonry walls to floor height.

That's a future job. And it won't be an easy one. I'll need to build a 10 foot high CMU wall of which only 2 feet will be exposed. The issue is that there is a downslope just beyond the building site. I've measured it, and looked up code requirements for footers near slopes. Hence a need to locate the footer really deep. (My calendar probably needs to be cleared for an entire summer...)

 

[The Tool Tyrant]

Those lucky 'flatlanders' don't know how good they have it, do they?

I totally understand your situation. I'm guessing it's a fairly steep slope?

'Back in the day' it was a fairly standard rule, '2 feet deeper than 7 feet away', but now there are many variables in Ca. depending on location and slope angle.

 

[FordTruckWench]

I'm guessing it's a fairly steep slope?

1.2:1 once it gets going, i.e. not quite as steep as 45 degrees. Then perfectly flat ground. Then a vertical drop into a creek.

'Back in the day' it was a fairly standard rule, '2 feet deeper than 7 feet away', but now there are many variables in Ca. depending on location and slope angle.

It is something like a 3:1 slope line from the footer to the toe of the hill. I don't know which toe, the flat or the creek, but both result in the same requirement.