Load Transfer

[outhouse]

How do header loads transfer to built up posts if the header is only sitting on two jack studs?  

[glenn-k]

This should answer part of that.

http://www.taunton.com/finehomebuilding/how-to/articles/anatomy-stud-framed-wall.aspx

You only need to transfer the load of the studs broken by the window- it needs to get down through the jack studs to the lower framing members and from there to the foundation piers etc.

Jack studs and king studs

The header is supported by a jack stud at each end. Jacks, sometimes called trimmers, fit under each end of a header, and they transfer the load that the header carries down to the bottom plate and the framing beneath. Nailed to the jacks are full-height studs called king studs; they support the assembly between the plates. Sometimes jacks must be doubled on wide openings so there's enough supporting surface for the header to bear on. Jacks can be replaced with a steel header hanger attached to the king stud.

[outhouse]

Thanks Glen. I thought I was seeing instances where jack stud support did not match normal stud support.

On a similar topic, I found this link with snow/wind/rain data: www.asicoverbuildings.com/pdf/specifications/MBMA2002.pdf , but I'm not sure how to convert to a psf live load value for calculating loads. Is there an IBC table that has this conversion, or is it case by case ?

[glenn-k]

If I understand you right , it is case by case.  John has explained how you totaal all loads for the house then carry them down to the footings to see how many you need and what size etc.  You woulwould have roof live (snow)  and dead load - loft or second floor, first floor combined then spread out over the appropriate footings - each carryng it portion of the load by the number of square feet it is supporting,  Framing members have to be sized accordingly.  

John's plans have that already done for you, so that is the easy way to do it but it is always of value to understand how it is done.

[youngins]

This discussion on load transfer got me thinking about my plans to do a hip roof on the playhouse.

My assumption is John's plans are setup where the load of the roof is transferred primarily through the two side walls. In John's little house example, IIRC, there was no need to put full headers for the windows on the sides which were not carrying load.

In a hip roof scenario, am I to assume that full headers would be needed for any opening in all 4 walls?

Are there any other considerations to keep in mind for a hip roof scenario?

Thanks

[glenn-k]

It looks like that would transfer the load of the end wall portions between the hips  to the end wall.  Also a ridge beam if it was used wouldn't get it's load to the endwall.  Seems like lots of things to consider.  Not referring to your case specifically and just thinking out loud.  I don't really know anything.

[youngins]

I'll post a separate thread in the plans support.