Sizing Headers - Residential Construction 1

[phamENG]

Curious about how others are handling this. I've seen a lot of drawings that have a generic header schedule with sizes based on width of opening. Presumably, the worst case supported joist span is selected and a header is selected for each opening width. This lends itself well to exterior headers so you can also define king studs and sills (which are based primarily on area). More than likely it's a typical schedule that just gets dropped on drawings without much consideration for openings less than 6' wide. The other option is to size each header individually.

I go with the latter option. It's time consuming and monotonous. But a lot of the houses I do are custom with widely varying joist spans and often have openings that don't align. So to do the first option, I'd have to size the 3' wide headers in non bearing walls the same as the 3' wide header transferring the reaction of the jack studs above carrying a 12' wide header. I went for a hybrid once - "Refer to schedule for header sizes UON" - that turned into a mess and I'll never do it again (never a good thing when they miss the note saying to use 3 LVLs and put in a triple 2x8 per the schedule...)

How are other residential structural engineers doing it?

 

[kissymoose]

Generic, conservative schedule with little sketch of the king/jack/header. Then for any openings too long, with big point loads, or too close to top of wall, custom calc'd and sized on plans.
After seeing enough headers in non-load bearing walls, I don't think most contractors care that they could've used (2)2x8 instead of (2)2x10 in less heavy-laden bearing walls.

 

[Craig_H]

I generally do a generic schedule. I try to use the same labels for windows and doors as the architect to avoid confusion. For the occasional header with a large point load or other unique circumstance, I often label it as the window tag + an asterisk. For example, W8* is a window from my current project with a 4-ply LVL landing on top of it. The other W8 windows are labelled as such and can have far less wood.

 

[Aesur]

For larger commercial we tend to design worst case and use a typical lintel schedule with special lintels where needed. For the high end single family residential we design each lintel separate, grouping where we can.

 

[gte447f]

I'll use a schedule if there is some significant economy to be found by doing so, either in design effort or drafting effort. Otherwise I usually label each header on the plans. Even if I label each header on the plans I may still only design for worst case(s) and oversize some or all of the other headers by labeling them for worst case also. Depends on how much overkill the worst case is if applied to other headers. Most of my projects are small though, so oftentimes there is not a lot of economy to be gained by grouping and/or scheduling the headers.

 

[phamENG]

Thanks, everyone. Doing each one individually often feels soul crushingly inefficient for me, but I have a (perhaps irrational?) fear that doing a more 'typical' schedule will result in less efficient designs with respect to material.

Maybe I should lighten up a bit...

 

[Craig_H]

Regarding efficiency, my own experience is that the simplicity of a consistent window schedule prevents field errors and that more than pays for the difference between some 2x8 and 2x10 stock. It also makes it far simpler to inspect when doing field reviews.

 

[Celt83]

phamENG:
you running full revit yet? There is an automation path with Dynamo for individual header designs that isn't too cumbersome to setup.

That said we go with a standard schedule. There is a back up excel sheet for the schedule that indicates what the typical schedule headers are good for using standard resi loads of SDL 25 and LL 40. Anything that doesn't fit the mold gets called out on plan.

 

[phamENG]

Celt - not yet. My current subscription is up in March, so I'll be upgrading then. (No Black Friday sale on the AEC package.) I'll have to explore that when the time comes.

 

[driftLimiter]

@Celt83 Im curious about the dynamo workflow for header design. Are we talking analytical members and loads or reading parameters from windows and door openings and coming up with the header 'behind the scenes' and tagging it accordingly?

 

[Celt83]

workflow consists of:
Add shared parameters to the typical wood beam family or a custom wood beam family, as instance parameters.
SDL
LL
TribWidth

The SDL and LL parameter would be PSF values, working on the assumption that your typical headers only support a single floor.

Using Dynamo pull all the wood beams, this is where a custom beam family can be nice so you avoid any post processing on the selection.
[ul]
[li]For each beam read the loading parameters work out shear, bending, and EI*deflection.[/li]
[li]proceed with either a pre-built excel table of your header schedule against those values or program the NDS beam calcs in dynamo directly[/li]
[li]have dynamo either change the beam instance to the header that works or populate the comment field with what size to change to.[/li]
[/ul]

optionally create a Revit schedule for the headers which is now custom for the job.

The process above can be expanded to include jack+king calcs as well. I would add shared parameters for Jackqty and Kingqty and populate them with dynamo to then again live schedule.

 

[Celt83]

The analytical member approach never quite works the way we want for wood design and documentation because you'd want to put pin supports at the member ends in RISA/ROBOT/Elements which would typically translate back to Revit when you link it so that the beam size updates, to do it "right" you'd need to model posts on each side of the header so the full post and beam stick model gets passed back and forth.

 

[XR250]

I hate residential drawings with any schedules. I think they make the drawings more complicated to follow for the quality of the current labor force. I generally call out a typical size - say (2)2x6 UON for smaller headers and then individual design for longer ones. Honestly, it takes me 30 seconds to size a header and kings so it is no big deal.

 

[kissymoose]

To clarify, my schedule is like what you'd find in the IRC. If it supports a floor and is in this range of lengths --> (2)2x8, if it supports a floor and roof in this range --> (2)2x10, etc.
I'm not labeling each opening and sizing it in a schedule, I'm leaving it up to the contractor to find the size in the schedule based on the length and loading.

 

[bones206]

Is there an assumption of a typical joist span and roof truss span embedded in these tables?

 

[phamENG]

bones - that's one of my issues with going that route. To be comfortable with it, I'd probably want to regenerate the table each time using the worst case joist and rafter/truss span in the building. Though that wouldn't be too hard to automate with an excel sheet.

XR - a similar thought put me onto sizing each and every one. But given my current team size (just me), streamlining drawing development is a big motivator.

 

[kissymoose]

Is there an assumption of a typical joist span and roof truss span embedded in these tables?

Assumed 18ft max joist span, noted on detail that it doesn't apply to larger joist spans.

 

[DoubleStud]

I do one line type for typical headers and note it as (3)-2x8 with one 2x6 king stud and one 2x6 trimmer. If that is not the case, I label both beams and trimmer.