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Attaching heavy timber stairs in a frame

Started by danreed76, July 29, 2014, 10:44:25 PM

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danreed76

In an effort not to change topics on another thread, thought I'd repost this here.

What are some methods of attaching heavy timber stair stringers in a frame?  With all the exposed timber in the frame, it only seems fitting that the stairs match, but I haven't seen any references to them in the books.  This will be a two section staircase, reversing direction at a landing, with both posts and beams available to attach to.  I'll try to post a picture of the stairwell and landing if that helps, but all thoughts are welcome.
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D L Bahler

Timber stairs can be very attractive if done well. And there are a lot of different ways to make them.

I will say that my knowledge of timber stairs is limited pretty much to Swiss building, but still this is useful.

Very often, their stairs will have their own framing that is attached to the structural frame, so we would use horizontal supports for the stringers, for example, that are tenoned into the posts rather than attaching them directly. This horizontal member also serves to define the landing point for the stairs (it is good to cut a rabbet on the back of the support to hold the floor boards, so that the top of this support beam is the same level as the floor. This greatly simplifies stair layout, and the support beam functions as the top step.)

The stringers are cut with a notch and slide down into corresponding notches cut into the support beam.

treads can be either massive blocks that are pegged to the surface of the stringers, like so: 

  from a castle tower.

OR they can be planks fitted into grooves cut into the stringers, secured with pegs.

Also, look at the way this stair is framed, and how the handrail is framed as well.


  

 

danreed76

Dave:

Thanks for the reply.  I had considered attaching the stringers using the beam at the second floor level as the top step, but wasn't sure the best way to fasten it.  I have some leeway for joinery at this beam, as it's somewhat oversized, simply to keep the look of all the interior beams consistent.

Below is one concept I had for the stairway.  Some of it looks odd because I hid the timbers that were in the way of seeing it.  I promise, I'm not trusting the air to hold anything up (except the stairs right now).


 


 
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BCsaw

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timberwrestler

It looks like the stringers are bearing very minimally on the header/joist.  You may want to deepen that beam for better bearing.  If you really don't want to, then the beefy tread bearing may be enough if it's well connected to the stringer. 

Alternatively, if there's an interior stick framed wall there, you could let the stick frame do the work.

Looks nice.  I just did 5 flights of stairs like that in a house.  Make sure that your treads are thick enough to avoid the 4" min gap.
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danreed76

TW:

Thanks for that feedback.  That was one of my concerns, that there would not be enough bearing on the beam.  To that end, I had considered either adding another step to the stringer and making the top step level with the second floor (and do the same at the landing), or going to a closed stringer with the treads in between.  If that were the case, could a tenon or tusk in the end of the stringer be used to secure the stringers to the beam, or should they be screwed to the beam for security?

How about fastening the treads to the stringers?  I've laid out and built stairs before, just never with timber.  There are some places I'm having to use screws to meet code ( mainly rafter feet and connecting the posts to the foundation), so I'm okay with that if it's the only safe way to do it, but want to explore other methods as well.

Do you have any pictures of how you fastened the stairs you built?
Woodmizer LT40 Hydraulic with resaw attachment |  Kubota MX5200  | (late)1947 8N that I can't seem to let go.

Thehardway

Make the stringers a little beefier, and wider. They look a little under proportioned in the drawing.  The weight of the stringers and treads will for the most part hold the entire section in place just like a ladder leaned against a wall.  A 3/4" trunnel can be driven through the top of the stringers into the face of the header beam at a 45 degree angle to prevent any downward movement at the top. This would not eaken the header as much as a M&T joint which you would have no real way to fasten.

The pictures DL posted show traditionally pegged treads to the stringers left proud. In cases like this, square pegs slightly larger than the dia. of the hole with a slight taper were often used to prevent prevent the treads from lifting.  They provided a wedging action similar to a cut nail.
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bigshow

 

 


I totally changed the entire design of my stairs after the frame was done.  I added a short girt and kneebrace to a post for the 2nd level landing, and added two posts under two existing beams (butt joints, screwed in), and added a freestanding post on the railing side.  I just forced these in and made it work.  I had originally planned on making a spiral staircase. I'm soooooo glad i didnt.
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frwinks

That's a stunner bigshow smiley_beertoast
Mine is far from finished, but it beats the ladder for now :D  11x11 hemlock stringers with dfir treads. 


simple lap joint and timberlocks hold the top of stringer to the header beam.  All treads are reclaimed old growth dfir, I was able to bookmatch the top step/landing 8)
 

danreed76

Quote from: bigshow on July 31, 2014, 09:54:38 AM
I had originally planned on making a spiral staircase. I'm soooooo glad i didnt.

I had thought about the same, but then envisioned moving large pieces of furniture. Spiral got nixed pretty quickly.

Definitely some excellent staircases, gents.  I reckon overall I was complicating the joinery issue in my head.  Seems the approach is pretty simple as long as the design of the staircase itself isn't too elaborate.
Woodmizer LT40 Hydraulic with resaw attachment |  Kubota MX5200  | (late)1947 8N that I can't seem to let go.

timberwrestler

These stairs sat between the stringers on angle iron cleats.



The bottom 2 flights used waney, naturally curved hard maple stringers.  One had closed risers to enclose the mechanical room below.



If you're in an area with a building code (and most are these days), then watch out as that is one thing that most inspectors will check.  You don't want to have to rebuild you stairs because the last risers is 3/8" less (or something silly like that). 
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BigJim2185

Awesome pictures in this thread. 

If you have The Timber-Frame Home by Tedd Benson, there is an interesting stair detail on pg. 207.  For an open riser stair, he shows newel posts that are joined to the header (lapped and housed? that's what I would call it...but I don't know what I'm talking about).  The newel post extends below the header and has a pendant detail at the top and bottom.  The stringers tenon into the newel posts - two tenons are shown on each stringer. 

There are also some pictures of open riser stairs in this book (example pg. 208) with newel posts that are tenoned into the header and do not extend below it.  I would guess that in this case the stringers are tenoned and screwed into the header and the bottom of the newel post.

Really great pictures guys.  Makes it very clear this is a good place to seek advice.   smiley_beertoast   
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bmike

Quote from: timberwrestler on July 31, 2014, 11:33:53 AM
These stairs sat between the stringers on angle iron cleats.



The bottom 2 flights used waney, naturally curved hard maple stringers.  One had closed risers to enclose the mechanical room below.



If you're in an area with a building code (and most are these days), then watch out as that is one thing that most inspectors will check.  You don't want to have to rebuild you stairs because the last risers is 3/8" less (or something silly like that).

that is a handsome set of stairs... nicely done.
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razor


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