# Hip rafter to ridge beam brace - porch roof where ridge beam is actually a ledger?



## MikeC (Nov 3, 2013)

2009 IRC, R802.3



> Hip and valley rafters shall be supported at the ridge by a brace to a bearing partition or be designed to carry and distribute the specific load at that point.


In this case, it is a front patio roof.  The ridge is not a ridge, but a ledger board on the house.  Instead of a shed style roof, they are building hips at the corners.  What type of connection am I looking at to maintain compliance with R802.3?  How about jack-rafter to hip rafter connections?  This is wood framing.


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## jar546 (Nov 3, 2013)

The intent of that was for the hip/ridge board connection point. A ridge board, properly designed is a compression point and not load bearing.  The top of the hip/valley IS a load-bearing point which is why you need the support to a load bearing wall.

In your case, since the "ridge" is actually a ledger that will be properly attached, you don't have that problem and a support is not needed.


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## Rider Rick (Nov 3, 2013)

That is old school construction. I see no problem as long as there is positive connection.


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## peach (Nov 3, 2013)

I can't quite wrap my head around what this porch might look like; the ledger board is fine for a shed type roof, but hips/valley sets are a little different since they become load bearing members in most cases.


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## MASSDRIVER (Nov 4, 2013)

Peach, just section a roof. Imagine a pitch going up a wall, then a horizontal run, then the pitch going back down. The hips intersect where the pitch and horizontal planes meet.

Brent


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## DRP (Nov 4, 2013)

The connection of the hip to ledger should be strong enough to carry ~2/3 of the hip's tributary load. The hip is a beam with the load increasing uniformly towards the ledger.


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## fatboy (Nov 4, 2013)

Is there a pic attached to this? If so, I am not seeing it...............


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## DRP (Nov 4, 2013)

See if the graphic on this calc works for the situation;

http://www.timbertoolbox.com/Calcs/irreghip.html

Basically slap that picture against the house wall.

Umm, let's see if I can make that pic appear here;







For the hip trib load;

Take the measure of the base line where the arrow is pointing that reads "major plan angle", multiply it by the horizontal span length formed by the bottom of the blue triangle and multiply by .5 (remember math class, area of a triangle = 1/2 base times height, we are getting the area of that triangle in Plan, overhead, view) there's the area of what is bearing on that side of the hip.

Do the same for the minor side of the hip.

Add those 2 areas that are tributary to the hip together and multiply by the design live + dead load, the sum is the total load on the hip.

The formula for the reaction of the heavy end of a beam where the load is uniformly increasing toward one end is R= 2W/3... multiply the total hip load by .66 and you'll have the load at the hip to ledger connection. That is technically the load to be supported if you don't want to go into diaphragm action which is the intent of that prescriptive section of code. At it's simplest, if there is a ceiling ledger I can get some ledgerlocks into with shear values sufficient to resist the load then a post from that ledger up to the hip is the easy way. Otherwise calc the hip connection and design, the awc connection calc may help or ledgerlocks thru the hip into the ledger and same from ledger into the house may be sufficient. Here is one of the places where Simpson isn't your only way out, sheet metal with a nail thru it does have a design value in that connection calc... you can site fabricate this strapping.

For the jacks take the trib from the long side of their tributary area, calc load, half is bearing on the hip, half is bearing on the carry beam, connect to the hip sufficiently to support half the total jack load, usually a few nails is fine for these types of spans.

In reality, I've only seen the hip seperate and begin to come down if the carry beam tilts out. I worked on one where that was a barn shed roof. The hip was pinned to the wall with 3 nails, the corner post was installed on a cow pie and the carry beam was a flatways 2x6. The diaphragm was provided by leadheads in 5v tin. It had lasted in that condition since the 40's and the hip had been disconnected for some years. Severely distorted but it hadn't gone Whump.


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## jar546 (Nov 4, 2013)

Excellent post DRP.  That should answer most questions.  Nice!


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## MikeC (Nov 5, 2013)

jar546's answer was sufficient and made perfect sense.  Thanks to DRP, I now know more than I ever wanted to.  That website he linked to is cool too.


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