This is in regards to a planned 20 X 40 two-story universal cottage. I'm thinking of changing the staircase from the U-shape of the plans (which I've already purchased) to a straight run. This straight run would begin about ten feet from the front door and go along one of the "long" walls for roughly 15 feet (terminating in a landing, from which one would pivot 90 degrees and take the last two steps up to the second floor). I figure I would need to run a beam parallel to the outside wall for my floor joists to rest on, and then support that beam as if it were the outside wall. Similarly, since I plan to do a full basement, I would need to do something like this in the basement, and also add footer support beneath the poured basement floor.
Are there other design/support issues I am missing here?
My main reason for doing this would be to widen the dining room area (from what is shown in the plans).
Thanks in advance.
Here is the link to the visual stair code tutorial = http://www.stairways.org/pdf/2006%20Stair%20IRC%20SCREEN.pdf
Assume 108" floor to floor divided by 15 risers = 7.2" rise and 14 treads @10" = 11'-8" long. In addition to about a 3'-2" wide opening you need a 3' x 3' landing at both the top and bottom. That totals 17'-8" along the long wall.
There is an excellent tutorial in the Wagner book on p. 165 "Building Straight Run Stairs". Normally you frame the opening (the same on all floors) by doubling or tripling the side joists and using a double header across for the joists to land on. Note that the opening only needs to start where headroom starts getting close to 6'-8". (Usually around the 2nd or 3rd riser.)
http://www.countryplans.com/books.html
(http://www.countryplans.com/images/wagner-sml2.jpg)
If you want a few risers on the turn you can shorten the length and widen the opening (and then support the intermediate landing). Draw it out to scale to make sure you make the right sized hole. If you don't have to meet current IRC code you could build the above stair with 14R @ 7.71" which is not too steep as 7-3/4" was standard until a few years ago.
Great Book!