Expert: Dan Griffin - 7/7/2008

Question
Hi,
We want to replace a window by a patio door.
We have removed some bricks above (and put a steel lintel to support the bricks), to have more height for the door, but now we need to replace the double 2x10 header which was there because it take too much height. Going up to down we have :
- the plywood floor upstairs
- a 2x10 (joist)
- double 2x4 (on top of the wall),
- and a conventional header (made with a 2x10 + plywood 1/2 + an other 2x10).

The final rough opening for the new patio door will be 71 1/8" (width).  Now there is only 7 1/2" from the base of the 2x10 floor joist to the opening where the lintel is. If we put back the double 2x4, there is only 4 1/2" of height for the header. I'd like to know Which type/size of header do you suggest and how to fix it.(if possible lvl otherwise steel i beam)
Thanks a lot for your time.
Regis.

Answer
The double plate has little or no value at this time.  It was there to transfer vertical loads where there was not a header so that the upper framing did not have to line up with the lower framing.  This leaves you with 7 1/2" for the header which is still very marginal.  Have you double checked the rough opening requirements for the new patio door?  They would normall fit quite well under a normal header.  I would have expected a 2x12 header on the existing, not 2x10, and would have still expected the standard patio door to have fit quite well.

I am not a structural engineer and you have presented a scenario that is far from using standard header tables.  A strucdtural engineer would need to access the loads imposed on the wall from overhead including the  roof (40 live/15dead), snow, wind, and the second floor (40 live/10 dead) to size the beam required to span a six foot opening.  I suspect some form of flitch plate will solve the issue.  You need to calculate or have an enginer calculate the lbs. per foot that the beam must carry.

Here is a source for a manufactured flitch beam.
http://www.readyheader.net/DougFirA36SteelPlate.aspx