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Author Topic: U-Shaped Stairs in a Timber Frame  (Read 1629 times)

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Offline Don P

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Re: U-Shaped Stairs in a Timber Frame
« Reply #20 on: June 20, 2017, 07:54:40 pm »
Quote
The code (as I read it) requires 6'8" vertical height.  You can have the nose of a tread just back of the beam and have less than 6-8 and the next stair down gives you the height requirement.

This isn't quite right. run a line or lay a board down the stairs resting on the nosings. From that line now plumb up to the headbanger, that measurement needs to be 80" or greater.

The visual interpretations download from these folks is good;
http://stairways.org/

Offline ljohnsaw

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Re: U-Shaped Stairs in a Timber Frame
« Reply #21 on: June 20, 2017, 08:00:23 pm »
Quote
The code (as I read it) requires 6'8" vertical height.  You can have the nose of a tread just back of the beam and have less than 6-8 and the next stair down gives you the height requirement.

This isn't quite right. run a line or lay a board down the stairs resting on the nosings. From that line now plumb up to the headbanger, that measurement needs to be 80" or greater.

The visual interpretations download from these folks is good;
http://stairways.org/

That makes sense.  But I didn't draw it that way and they approved my drawings.  I'll have to go back and measure to see if my stairs will actually pass code!
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 38" cut Bandmill up to 64' - using it all to build a timber frame cabin.

Offline timberwrestler

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Re: U-Shaped Stairs in a Timber Frame
« Reply #22 on: June 20, 2017, 09:13:49 pm »
Quote
The code (as I read it) requires 6'8" vertical height.  You can have the nose of a tread just back of the beam and have less than 6-8 and the next stair down gives you the height requirement.

This isn't quite right. run a line or lay a board down the stairs resting on the nosings. From that line now plumb up to the headbanger, that measurement needs to be 80" or greater.

The visual interpretations download from these folks is good;
http://stairways.org/

Yup, Don is right.  You might get away with it with your interpretation, but it's risky.

Offline jb9

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Re: U-Shaped Stairs in a Timber Frame
« Reply #23 on: June 21, 2017, 08:12:10 am »
Thanks for the clarification.  I was aware of that line across the nosings.  It's probably better to apply the actual standard.  Given that reality, I went ahead and took a measurement and got 6' 9 3/16" and carried up the angle of the nosing reference line (37 degrees).  I applied it to the beam to see what kind of a chamfer would match and restore the 6' 10 11/16" clearance.  It actually doesn't look like it would be too bad...  maybe a few passes with a block plane.  Ok, maybe a few hundred passes with a block plane.  :laugh:
 


 

Offline jb9

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Re: U-Shaped Stairs in a Timber Frame
« Reply #24 on: June 25, 2017, 07:51:34 pm »
Sadly, it's back to the drawing board on this...  I am working the heights on the descent to the basement and I need a bit more clearance.  I came to this conclusion when I started reading about the minimum required "throat" that inspectors like to see.  "Throat" is basically the meat of what is left on the stringer.  With 2x12 stock, folks like to see ~5 1/2" or perhaps 5" would be fine.  Regardless, I'm going to need a little more headroom underneath the stairs.  I was taking a look at your work timberwrestler and noticed that you have designed a few "housed stringer" staircases.  I'm kind of new to stair design (I have been wrestling with my own model for 2 years now) so I wasn't totally familiar with how to draw one.  I think a "housed stringer" or treads held up by brackets address the stringer throat depth encroachment issue I am seeing with height clearance.  Has anyone here ever designed a housed stringer or a stringer with brackets to address height clearance?

Thanks and I will post some drawings soon.

Offline timberwrestler

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Re: U-Shaped Stairs in a Timber Frame
« Reply #25 on: June 26, 2017, 08:40:31 pm »
jb9,

There are some guidelines for throat (although I've never heard that term), but I don't think there are requirements.  If you need to make it a bit thinner there are a few tricks.  You can always sister an extra piece on the side that hasn't been cut-like a 2x4.  Or you can use engineered wood like LVL or LSL for the stringers.

For more traditional staircases, we often do housed stringers, where the whole stair assembly is wedged and glued together and then set as a unit.  Andy Engel's stair book is really the best modern resource.  I also help teach a class in doing those stairs at the Heartwood School.

Another style that is pretty easy, and that often fits in with timber framing is to use a timber as a stringer, with thick treads sitting on brackets (or fully housed).  These stairs are just 4" pine treads sitting on angle iron.  http://www.uncarvedblockinc.com/architects-additions.  Most of the stringers were just pine timbers, a few were curved waney pieces.

Offline jb9

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Re: U-Shaped Stairs in a Timber Frame
« Reply #26 on: June 27, 2017, 08:33:45 am »
Thanks Timberwrestler.  From what I understand, throat is the wood that exists at the bottom of the stringer.  I do think that housed treads or angle-iron treads will work.  I redrew the stringers with 1 3/4" of reveal above the stairs.  Here's what it looks like.  The height gained is very noticeable.  I will have to use 5/4 treads and I may have to increase the size of the bay by 1" or 2".  Not sure yet.  I just want to make sure the bay will work even if I have to sub out the stairs to a master stair builder.

Here is a rendering:
   

 

Offline Don P

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Re: U-Shaped Stairs in a Timber Frame
« Reply #27 on: June 27, 2017, 12:42:28 pm »
Have you checked height from landing platform framing to basement stairs? that looks like the pinch point.

I've lost the pics... well they're here somewhere on floppies but that was 2 computers ago, for heavy timber stringers you can cut out an L in plywood to make a jig that a router base fits inside of and rout out the housings for a set of timber stairs pretty quickly.

Offline jwilly3879

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Re: U-Shaped Stairs in a Timber Frame
« Reply #28 on: June 27, 2017, 12:55:21 pm »
I have made fake housed stairs by cutting the stringer out of 2x12 and then attaching a full 2x12 to the outside of the stringer.

Offline jb9

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Re: U-Shaped Stairs in a Timber Frame
« Reply #29 on: June 28, 2017, 10:29:32 am »
Thanks Don P and jwilly3879.  I doublechecked my height clearance on the landing and it's looking pretty good ~6' 10 3/4".  My basement stairs will probably be 7 3/4" rise and my main house stairs will be 7 9/16" rise which is an acceptable delta within IRC Code from what I understand.  This will also help with the height clearance.  I will probably do a traditional stringer in the basement and use the housed stringer for the main level.  I will post a rendering later this evening.  I may have to use 1 3/4" LVL stock but that's fine.  Regarding the housed stringers, I found some great videos posted by master stair builder Keith Mathewson.  His layout instruction and craftsmanship are excellent.

Offline jb9

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Re: U-Shaped Stairs in a Timber Frame
« Reply #30 on: June 30, 2017, 08:11:15 am »
As promised, here's a new rendering.  This is the triple header (plus angle iron) on the last flight into the basement.  Having offset (or uneven numbers) of stairs in a U-shaped stair case does seem to present difficulties in stair opening headers, but I think because my house is so small, I would rather make what I have work than continue to expand the footprint of the structure.  Does this look reasonable for a stair opening header?  3 sets of 2x joists sistered together?

Thanks in advance.