Jack studs

[Squirl]

Do jack studs have to be directly against a king stud to count towards jack stud/header requirements?

[rdzone]

I can't really answer your question, but I am trying to picture why you wouldn't have them next to the king stud  as I always nail through the king into the header???

Simpson does make some connectors for headers, which would eliminate the jack stud.

[Squirl]

In the design for my house I wanted to have the greatest flexibility over time (add a second floor/change window size) and ease of construction. I have a double 2x6 as my header and a jack stud on each side.  I realized in the code charts that if I or someone else were to add a second floor, it would require two jack studs instead of one for the header.  I was already planning on an extra stud around the window.  Would that count as an extra jack stud?

[Squirl]

The reason I ask is I am trying to eliminate as much stud heat loss as possible.

Also on the same topic.  Does anyone know if I can't use 2x4s for the jack studs or do I have to use 2x10s?

If I use 2x10s, should I notch them for the header?  A double 2x10 top plate to a 3 inch wide header and back to a 9.25 inch wide stud seems a little unbalanced.

[rdzone]

you could use these

http://www.strongtie.com/products/connectors/hh.asp

and run you headers full length and call the others filler studs. 

[Squirl]

No.  I checked that a while ago.  All simpson header hangers that I could find are only for 2x4 and 2x6 framing.  I have 2x10 framing.

[rdzone]

missed that.  I didn't read your post well enough. 

see if one of these help

http://www.buildingscience.com/documents/published-articles/pa-future-of-framing

http://www.buildingscience.com/resources/high-r-value

[Don_P]

With 2x10's for studs I'd let them in to both a jack and king that run full height. You get the increased bearing of a double jack without really weakening that deep a stud. I'd let in from each face.

[Squirl]

Thank you both. 

Don_P I like the idea of letting in the stud on both sides.  It will give me the ability to fill the header with insulation.

I read some of those articles at the designing stage. The first article is spot on with many of the building theories that I am trying to implement.  The only difference is I am using extra thick walls instead of exterior foam for many reasons.  I am trying to get to "Extraneous studs, headers, and plywood don't boost structural integrity as much as they sabotage energy performance."

With full blocking on all my sheathing with a 2 inch nailing pattern and 2x10 studs, it far exceeds code and even many strength requirements under high wind framing guidelines.  I was looking to see if anyone knew of any framing violation for using jack studs not the full width of the king stud.  Since all my framing books and all code charts only cover 2x4 and 2x6 faming, the question is never even addressed.  My feeling was if the code charts say 2 jack studs and it doesn't matter if the walls are framed in 2x6 or 2x4, it doesn't matter whether the jack studs are 2x6 or 2x4.  My plan was to go from a 2x10 king stud, to two 2x4 jack studs, to a 2x10 which will be the edge of the window frame which the sheathing and drywall will nail too.  This way the area will be filled with extra insulation instead of studs.

I think I found some direction on the first answer in a footnote in the header section of the ICC.

. NJ - Number of jack studs required to support each end. Where the number of required jack studs equals one, the header is permitted to be supported by an approved framing anchor attached to the full-height wall stud and to the header.

My reading of that footnote is the jackstud has to be at the edges next to the king stud to be considered towards the jack stud requirement.   My reading of it would also eliminate the use of strong ties (framing anchor) when two jack studs are required.

Does anyone know of any similar provision on required jack stud sizing?

[Don_P]

The purpose of the jack studs and the reason for a callout in the tables for 2 jacks is to provide enough bearing surface under the header that the jack(s) do not crush into the loaded header. Assuming sheathed walls, it's up to your inspector but I would be satisfied with headers let into the kings and 2x2's well nailed under the headers as jack#2.

The engineering path is to determine reactions at each end of each header board and provide enough beariong area to keep the compression perp to grain below allowable levels.

[Squirl]

Thanks Don_P.  I like that idea. 

This probably won't get a peep out of the inspector.  The second jack stud requirement is only if a second floor is added later.  Then I won't have to rip out every window to add a jack stud.  It leaves options for me and later residents.

[John Raabe]

In advanced framing where you are trying to minimize the solid wood heat transmission the headers are supported by either being let-in to the studs, or using metal hangers. If you let-in the header on the interior side you can extend the width of the header for anchorage of drapes or other window hardware.