Timber frame SYP air dry time before build

[Georgia088]

Hello all!
I have a SYP that I have cut into 2-1/4 thick slabs 14" wide. I am planning to build two sets of steps going in to my house (total rise is 36") I am planning to build them timber framed style; cutting the joints with a cnc router. (Although I have never done this)

I hope the wood itself will help "hold" itself together as it dries and help prevent warpage and cupping. 

I just cut the tree down about 2-3 weeks ago. And I sawed the lumber yesterday. I have it stacked air drying now out of the rain. I am in Georgia (humidity high). When finished these will be under my garage out of the weather. 

I am not planning to plane as I want the rough cut look. Finally, to my questions. Main question, how long does this need to air dry before I try to cut my joints and put together? Fwiw, I needed it done yesterday, my wife is on me about my "temporary steps". 

Other question what's the best way to connect these stairs (timber frame style) to prevent unwanted movement?

Thanks!

[doc henderson]

If you are not going to joint and plane them you might as well build them.  are you doing dado joints?  is the lumber for the treads or stringers or both?

[Don P]

Untreated SYP outside, on the ground, in GA. This is probably not a long term solution.

On old time interior stairs the housing in the stringers for the treads was tapered on the bottom. A long narrow wedge was driven in to push the tread up and tight into the housing, and could be driven in further as the wood continued to season. Outside that is another water trap. I'd soak all this in copper napthenate if green is acceptable else borate with the knowledge that it will not last.

Building code says that a 4" sphere cannot pass through any gaps on a stairway. This is most often a problem at the railings but also comes into play in open tread designs where a riser is omitted. 
This comes into play if you are inspected or insured.

On heavy timber open stairs I've usually housed 4" thick treads about 1-1/2" into 4" thick stringers and then toe screw from below or run in from the outside of the stringer and plug. The thick tread gets me out of the 4+" gap problem.

[doc henderson]

you say under my garage, out of the weather...  what does that mean?

[Georgia088]

If you are not going to joint and plane them you might as well build them.  are you doing dado joints?  is the lumber for the treads or stringers or both?

I am planning to build the treads and stringers out of this lumber.  
They are going to be under my enclosed garage. So no rain water or major moisture. The stringers will contact the concrete floor of the garage, which I would usually use pressure treated for this, but I can put something down to prevent the direct contact of the rough cut to the concrete if needed. I plan to put some type of polyurethane finish on all parts.
As for how I am planning to connect, I really am not sure. I have seen images that I think you are describing above. Where the stringer is cut out and the tread is knotched to fit inside. On the outside of the stringer is a wedge that can be driven in to prevent the stairs from spreading apart and I assume can be driven down periodically to account for shrinkage
I am really wanting y'all's opinion on how to fasten them. Thanks for the help!
I am not overly concerned with an inspection or insurance. 

[doc henderson]

so are the stairs inside the garage?  so you can do a dado on the inner aspects of the stringers, and glue with no fasteners.  Or you can cut traditional stingers and place treads on top.  I like a riser kick board as well, as it supports the tread like a joist on the front, and fasten at the back as well.  you can peg it for a wood frame look.  you can use pressure treated stringers under the tread and behind the riser, and just put you rough sawn wood on the outside and get the best of both worlds.  you will only see the rough wood.

[Georgia088]

Yes, they are inside the garage. Ok. But you think it is ok to go ahead and build with the lumber green?
Thanks!

[doc henderson]

well I know you wanted our advice on the joint.  but especially if you cut stair stringer and put the treads on top, they can dry in place, and no mission critical fit.  so you might decide on the construction and then decide.  a dado is not going to be great since this is rough sawn so it will have a bit of a rough edge.  or if you want to go green and get it done, then make the construction decision based on that.  there are some standards for rise and such, and sounds like the total rise is 36 inches.