Gable Wall with Stairway
Gable Wall with Stairway
(OP)
I've come across this a number of times with my own designs and now this particular design:

A stairway next to a gable wall or exterior wall. My first thought is to call out a balloon framed wall up to the 2nd story top plate(s) but then that makes the rim board and double top plate of the first story discontinuous. Any thoughts on the best way to frame this small section of wall next to the stairs?

A stairway next to a gable wall or exterior wall. My first thought is to call out a balloon framed wall up to the 2nd story top plate(s) but then that makes the rim board and double top plate of the first story discontinuous. Any thoughts on the best way to frame this small section of wall next to the stairs?
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com






RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
Either double the studs [(2)2x6 at 16" oc], use 2x8's at 16" oc, use LVL or Paralam studs if necessary, which i doubt this wall is tall enough to warrant such.
All will depend on your lateral calcs.
RE: Gable Wall with Stairway
You can also view and download the 3D SketchUp model here:
https://3dwarehouse.sketchup.com/model.html?id=uf9...
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
The balloon framing makes more sense to me but then I realized I was losing a lot of continuity in the rim joist, first floor top plates and second floor bottom plate. I've run into this before and have never answered fully in my mind which is the better solution, and why.
I like the blocking and strapping at the rim joist, that would solve the continuity issues.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
I would do everything I could to make it work as platform framed, only because then I would be confident it will get built right.
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
1) I like the double rim board as a composite member if possible. It's stiffer that way. If you're going to separate the plies, you'll either need to treat them as two individual bending members (more deflection) or find some way to stitch them back together intermittently.
2) This method doesn't eliminate the eccentricity I had in mind. The sketch below shows what I was getting at originally. It was overly optimistic not to include it in the first place.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
Exterior walls adjacent to the opening shall be framed using full height studs where the opening is less than 2' from the exterior wall.
Then if you turn to the prescriptive section is shows a stairway next to a platform framed wall...
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
RE: Gable Wall with Stairway
The ceiling height in the model is shown as 8'. In reality it will be 8'-1". Subtract about 7.5" for the first step gives me a headroom of about 89" give or take an inch or two. This is assuming there are 13 treads. The framer may opt for 14 treads instead which would give me about 81" of headroom. I always like to err on the side of a little extra headroom for a stairway, for reasons of meeting code and also for functionality for the occupant.
In this particular instance the client made a point that they wanted more headroom and width so moving large pieces of furniture into the upper floor space would be less problematic. I've damaged a lot of drywall in my lifetime moving stuff up and down tight stairways.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
In my area I wouldnt get much grief for balloon framing 15' of area. Deflection I don't think is a concern as you have an adjacent low roof that can brace the wall.
I think where I would run into flack would be when I tell the contractor they have to use:
1) Continuous rim with interior LVL beam.
2) put beads of liquid nails to help bind them together.
3) nail them together with nonconventional nailing.
4) but small strips of blocking between the two.
5) insulate the space prior to closing (likely out of sequence)
If it were me and we werent using balloon framing, I'd 100% go with full width 4x10, 6x10 or PSL rim to span in weak axis across the opening. Sure the material may be more expensive but less labor and less likelihood of missinstallation.
RE: Gable Wall with Stairway
I agree that the safe bet is just to put a "solid" beam into the slot behind the rim joist and eliminate most of the special detailing required to form a composite beam.
Regardless of using a "wind beam" there still needs to be appropriate connections between the wall plates and the beam so that the loads are properly transferred into the beam from the the wall. What would be a more conventional way to nail the plates to the beam? I still think you are toe nailing into the first floor top plate and nailing down through the second floor plate as shown in the detail above, I'm not sure how else to do this.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
1.) 1-1/4" Rim Joist on exterior with a 3-1/2" x 9-1/2" PSL beam behind to span the 10'-10" of the stairwell.
2.) Remove the Rim Joist in this section and install a 5-1/4" x 9-1/2" PSL beam that spans the full 10'-10" of the stairwell.
3.) Remove the standard Rim Joist (1-1/4") along the entire length of the wall (24') and install either a 3-1/2" or 5-1/4" continuous PSL beam the entire length of the wall.
Or perhaps some other option I've overlooked.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
1) Normally, I'd assume the porch to be loading the wall laterally, not bracing it.
2) To utilize the diaphragm, by the book, you'd probably need to connect a bunch of things that aren't, by default, typically connected.
3) Owners generally feel at liberty to modify things like porches as they see fit. Most lay people -- and builders for that matter -- are unlikely to recognize the role played by the porch diaphragm in stabilizing the wall joint. And you're unlikely to saddle the building with some kind of plaque to that effect (porch removal = death).
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Gable Wall with Stairway
The eccentricity is small enough that I think it makes sense to just sandwich them together and make sure they act as one unit. I still like the idea of disallowing any splices in the members in this region of the wall and will keep my notes specifying that.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Gable Wall with Stairway
I'd personally let them splice the wall plywood at the rim but up to you. It's where they want to splice it and anywhere else would require blocking (assuming you have blocked shearwall).
RE: Gable Wall with Stairway
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com