14-24 plans- foundation questions

Started by dogneck, May 18, 2008, 08:16:13 AM

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dogneck

I was going to use sonotube foundation for what will be a storage shed using the 14x24 plans.  I was adding it to the rear of the house where 12ft of the 24' side would be adjacent to the house.
I was going to place the sonotube directly next to the house, so the connecting door would be have level floors.
Now, I find the house has it's concrete footer going out about 7".   I wanted to use that 12ft section rather than having the sonotube pier (at that location only).   The problem is with the leveling.   I would need 2x8 joists rather than 2x10.     The foundation ledge is 7 3/4 " from what would be floor level.  If I used 2x10, then with a 3/4 subfloor and 1/2 finish floor, it would be 2 3/4 " higher than the existing floor.  If I use the 2x8, then I figured about only 3/4" higher.   
Can I use 2x8 joists and double them up?   
I would use that for the whole section next to the house, then use 2x10 for the rest of the building.  It's more like two 12x12 ft buildings next to each other.  One would have the 2x8 joists and the other on the sonotubes would have 2x10 joists on the 6x12 beams. 

Someone said just to use the 2x10 joists and notch them out on the end, but how much of a notch could you make without losing the structural strength?
Thanks,

John Raabe

As long as you can get Doug fir or Southern Pine #2 or better you can use 2x8 joists @12" o/c in place of the 2x10's @ 16".



Then you could notch the bottom of the joists to make up your 3/4" difference if needed. (7.5"/6 = 1.25" max notch depth.)
None of us are as smart as all of us.


dogneck

It also looks like the D/3   which would equal 2.5".    Is that enough concrete footer under the joists to support it?
Due to trying to get it level to match the existing door--  could I place these treated joists directly onto the concrete footer-- without any bottom plate or sill (whatever it is called).   If I place them directly onto the concrete, I guess I would place some blocking to keep them from twisting.


Thanks,


John Raabe

Yes, you could bear directly on the footer I would think. It is done all the time with posts. Put a moisture break under the PT wood (sill sealer, 90# felt) and provide blocking for stability and nailing.
None of us are as smart as all of us.