Spiral Staircase Around Log

[CMaddox]

I'm talking with a builder about a spiral staircase with two landings around a flared cypress log, and I'm trying to wrap my head around laying out for joinery as well as find something techniques for strength and consistency. I've got a few ideas, but I'm wondering, does anyone have any resources they could point me towards or experience with this sort of thing?

 

[thsb]

http://www.stairporn.org/2010/02/16/kauri-log-staircase/

something like that would be nice ;-).

here is one where they used steel supports-seems expensive and a little complicated though, but i guess everything would be.

http://www.thelogconnection.com/newsletter_one.html?2009_05

 

[Skymaster]

Georgeous awesomeness absafantastic

 

[Jeff]

I'm talking with a builder about a spiral staircase with two landings around a flared cypress log,

Do you have a conceptual sketch or hand drawing to share? I'm also trying to get my head around some "how to" construction techniques for such a unique beast. I'm assuming this is wood construction around the cypress log as the center point. :icon_scra

Take a look at pic #26. This stuff looks really sophisticated to construct.

http://twistedsifter.com/2012/07/gallery-of-unique-creative-staircase-designs/

...and to its home page along with others...

http://www.logstairs.com/spiral.htm

 

[Jeff]

Found this design info too. It's a start with a few general dimensions to consider.

https://www.spiralstaircase.com/stop-and-stair/

 

[CrealBilly]

As with most things log - there's not a lot of "standards" but one thing seems pretty common the treads are attached to the log in a through tendon fashion.

You can see lots of designs by googling "log spiral staircase" in Google images.

One major design point I would be very concerned with is shrink down of the entire structure. Log walls will shrink down making the upper floor lower over time. The logs are stacked horizontally but the center log for the stair case is placed vertically. Lumber shrinks very little in length as opposed to thickness. So over time you'll have a mess to deal with if you don't allow for shrink down in the initial design. I believe for green log walls the shrink down is 1" per foot. But if your logs are somewhat more dry than green you will need to calculate the anticipated final shrink down based on moisture content. Now throw in two stories like you mentioned "two landings" and you can see my concerns.

Personally I like spiral staircases more so than straight stair cases. They seem more open and take up less space and are more pleasing to my eyes. But that's a personal preference thing...

If I were you I would most definitely get a structure engineer on this... there's just so many variables that need to be considered first.