Good questions. You are in the same boat I was last year. I captured quite a bit of the information and posted it. The link has the information.

A quick cut at the answers is provided below. See the link for where to get design/code info etc. I built my decks using the information in it and it is extremely solid - no bounce at all. One thing I did that I forgot to mention that may be overkill but.... Everywhere the IPE has a butt joint I doubled the joists and installed a waterproof membrane over the joists so no water would go between and potentially rot the wood.

Here goes:
1) staining the framing lumber: not sure but the wood is awfully wet. Why do this, it will be covered?

2) What length of screw needs to go through the joists? I used 8 x 2 1/2 and was very happy

3) Is the 2" x 10" enough? use of 2x10 will depend on the span. 16" for 4/4 Ipe is fine, 12" if on the diagonal. go to the link to determine size of joints, beams, piers, etc

4) Is 1/8" route on the butt ends the correct radius to use? Yes, but you may find that a rotary sander works fine. I did

5) How often will stain need to be applied to maintain that deep, dark finish? I live in Michigan and the deck faces south into dense woods. Annually? 2 years? Is TWP 116 still the preferred product? No idea, I cannot get the 116 in California. I used Messners and was not happy. Will try 516 next - ordering it Monday

6) I am not sure whether to use 4/4 or 5/4 Ipe. I have read the posts just not sure. Is there a different opinion if I use 3/8" plugs? Any reasoning is appreciated. 4/4 is fine and less expensive. I plugged some of the wood (both 4/4 and 5/4 and did not have any issues. Warning, sanding takes a while....

7) I plan on 48" x 12" wide one piece Ipe stair treads. I do not plan on having a riser on the steps creating a view blocker as the deck is 12' high and the underneath has seating areas and a patio. What thickness Ipe would you use on the stair treads? hmmm, mine are 48" and I used 4 risers. that's a pretty big span. recommend you reconsider. I went out and tested a scrap 4' 5/4 piece of Ipe and it bounces. 5/4 you can get away with 3 risers (one in the middle) as its good for 24" spans.

8) If using Ipe plugs what kind of glue do you recommend if any? Tightbond 3 (doesn't foam like gorilla glue does)

9) Is any adhesive required on the joists where the Ipe contacts them? Nope

10) When face screwing with no plugging I understand the nice straight line for the screws. When you butt two ends you will have four screws. Is there a recommend "pattern" for butt end joints on a 24" wide deck? ie 3-8', 2-12', 1- 10'& 1-14" or purchase all the same size. Do you " lay out the pattern so the screws look symetrical? I did mine so there was 3 boards before repeating the butt joint and it looks okay. Remember, I doubled the joists in those areas. You can see my framing in the link for the the deck by Salmon Slayer

11) Could the Ipe be powerwashed at the beginning of each season as it would look nice for the summer then hit it again every spring and forget staining altogether? Someone else has to answer than one- I am interested though

Steve

Here is a link that might be useful: IPE Deck Information

Steve,

Thanks for the reply. I appreciate the link it has a lot of great information.

Very Good Steve!! It would be a lot harder over here with out Ya.

Just a couple things ...
a new player is up with the outdoor finish >> www.wooddefender.com I put tightbond con adhesive on the joists if the project is low to the ground when decking with South American lumber. Not for the hold down power but as a buffer from moisture in the first few important weeks.

A Makita random orbital sander 60/80 grit pads is the best $50 ( or less) a person can spend when working with SA lumber.

The trade off using a power washer , that is driving water into the wood and a lot of sharp whiskers after it dryes out, might be worth it to some but not to me.

John Hyatt www.deckmastersllc.com.

Just one comment on the deck framing. You said the deck is 24 ft by 16 ft, and you will put a header at 14 ft from the house. And use 16 ft 2x10 joists sitting on top of the header and overlapping 2 ft.

My architect said that was no good. Using 2x10, he would put the header no more than 12 ft from the house, and overlap 2 ft, for a deck size of 14 ft. If you want to go to 16 ft on the deck, you would need to upgrade the framing to 2x12s.

I don't think what you are planning would meet the building code in Carmel NY. Obviously there are differences from state to state, town to town. I've used a bunch of architects before, and this guy have saved me money in the past by not over-engineering things for me.