How to install a new window header that overlaps an old one

Question

I'm attempting to move some windows. I have an engineer drawing up the exact plans of how to make sure it is structurally sound, but my question here is more on actual implementation.

In one or two locations I will be installing a new header of fairly significant size (~7') which is higher and offset from an existing header. This is a grade level previously converted carport that I'm leveling the floor of and incorporating into part of the house. The existing header is where the garage entrance use to be. It looks like this (orange is new header for a window [approximate location, does not include structural components, just for visualization of what I'm trying to accomplish]).

I have a hip roof and the ceiling joists for this particular location run parallel with the exterior wall the distance of both the old and new headers.

How can I add the new header safely and how much of the existing header do I have to remove?

My only thinking is to punch some holes and build some temporary supports perpendicular under the top plate... lots of work!

Answer 1

Based on your description of the loading, I wouldn't be too concerned about supporting it at all unless you're going to leave the framing out for any significant period of time (days for example). If anything it might sag a fraction of an inch, but you'll true it up when the new header goes in. You'll want to remove the old one first and re-frame that section of the wall, then cut in your new rough opening and put the new one in. Pretty simple, and I've done this numerous times with patio doors.

If you're concerned about the weight, consider that there are quite a few houses out there dating from the time before building codes became common that don't have proper headers over windows and doors at all. I've done several jobs where I had to install headers that were missing in the first place. Also, I've done a couple garage demolitions where I had a hard time removing enough structure to make it collapse.

Answer 2

The weight of the roof will be so little in that area, that if you have a fascia board, that will hold it together in a straight line for the short time while you are adding the header. If you have aluminum wrapped fascia, you will most likely have 2X material for a sub fascia, that's even better, unless it is a cover over an existing 1X fascia. Even if it sagged a little while you are getting your new header in will be of no concern. When you layout your cut on the existing studs where the new header will meet them, that itself, since it will be drawn as a straight line across the studs, cut as a straight line, from stud to stud, if any settling does occur, it will be picked back up when the jack studs are set under the header. One suggestion, use LVL for the header. Although all wood swells with humidity, LVL material to me is a lot more stable than regular framing. That way when everything is done, you will not have a dip in the ceiling and the cracking drywall related to wood movement at the header, from using regular framing. For example, when I framed my home, I used 2X12 headers everywhere. Back then I know wood shrunk over time, so I cut my jack studs in 1/8" longer than needed. Yes it put a hump in my top plate, but I figured it will shrunk and lay flat over time. Well it did, so much it still put a 1/4" dip in my ceiling over my doors and windows. So much for trying to compensate. Not that you will need something that wide for a header, it is just to make a point about how much regular framing moves.

Answer 3

Build a quick temp wall inside about 3' in so you got room to work. If the ceiling rafters don't bear weight on it just try and bridge over temp.wall to keep.things up. The temp wall is top and bottom plate and 2' centers with a stiff back 2x4 nailed a cross at center. Maybe a angle brace 2x4 0n the other. Put temp wall.in place and demo your wall. The wall that remains at the corner will hold more than you think. Good luck.