Long PT Stringers

Planning on building a set of outdoor stairs at a cottage that will have a total rise of somewhere between 12 to 15 feet along a steep slope. (Total rise from the cottage to the water is over 40 feet with a combination of ramps and stairs.)
The stairs will be approximately 40 inches wide with open risers and 3 notched stringers.
The stringers will likely be over 20 feet, so I am thinking I would glue up (Gorilla glue?) a stringer that is a PT 2 x 4 and 2 x 8 edge joined (16 footer and 8 footer). The stringers would have a scarf joints at opposite ends and the 2 x 4 would be on the bottom side of the stringer. (The 2 x 8 would be notched for treads).
I can provide midspan support from underneath.
Other ways of doing this?
Thanks
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If you can support the run somewhere in the middle, the stringers don't have to be continuous.
You should consider breaking up such a long flight into two sections with a landing in between. Every single person who uses the stair will appreciate it. Landings give people a place to rest (built-in benches on either side of a landing with a view is particularly nice), provide a place to arrest a fall, and some codes limit the height of an unbroken run of stairs.
R
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A place to sit and rest the inevitable cooler would be good. T
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I have to agree, landings are a good way to break it up, as the knees get older them stairs get longer and longer
wrote:

If you can support the run somewhere in the middle, the stringers don't have to be continuous.
You should consider breaking up such a long flight into two sections with a landing in between. Every single person who uses the stair will appreciate it. Landings give people a place to rest (built-in benches on either side of a landing with a view is particularly nice), provide a place to arrest a fall, and some codes limit the height of an unbroken run of stairs.
R
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Yes, I know a landing will help make it easier to navigate and a rest is a good idea. I am 58 and my knees are shot - but we are talking about a long rise (40 to 50 feet) with a combination of stairs and ramps to the water. So I am simply trying to come up with something that fits the location - not a page out of a building code.
wrote:

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Okay, fair enough. So the answer to your original question is - don't. Don't try to make a continuous stringer, and don't have an unbroken run of more than 15 steps or so.
As far as having something fit the location, that's a bit tough to see from here...
R
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I concur....landings along the way......break it up. john

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