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Removing portion of top plate.

8939 Views 9 Replies 5 Participants Last post by  Clutchcargo
I'm opening up a section of wall between a sunroom and the rest of the house. I'm planning on removing the bearing wall and I want tuck a beam/header (triple 12" LVL spanning just under 11') as high in a wall as possible. This involves cutting out the top plate. The original builders used a 4x6 placed vertically in a 2x4 wall for the top plate.
The question is, how do I tie in the new beam to the remaining top plate? I was planning on doing this late last year but my project got derailed because of lack of time.
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I would suggest you consult with a structural engineer. The top plate is not only a support for the weight above but is also the tie that prevents spreading caused by the roof system's outward push.
Set the beam on top of the wall on both ends flush with the bottom of the joist. Cut the joist on each side so the beam will fit between them. Use joist hangers to connect everything together. Make sure there is solid 4x4 post material under each end of the beam in the walls to support it.

Check roof bracing. Sometimes this will need to be worked with as it sits on load bearing walls.

Look into a glue-lam beam instead of triple 2x12s.

Johnny Jackson
Sounds like you have headroom issues, at least as I understand your post you are seeking to maximize the headroom by removing the top plate. You may want to look into a steel header, I used a steel I beam for a similar project. I only needed an 8 inch deep steel beam rather than an 11 1/4 inch deep LVL, the 3 1/4 inches I saved allowed me to leave the double 2x4 top plate in place.

As previously noted, you may want to consult with a structural engineer, or at least someone familiar with the process, since you are going to want a full design before you start. Some of the issues you need to address have already been mentioned, specifically how do you connect the beam to the vertical supports, what size supports do you need, how do you connect the vertical supports to the beam below the floor, temporary support of the floor above during the project.
To clarify,
this is between the first and second floor. The rafters are collar tied so spreading is not an issue.
If I put this flush with the bottom of the joist, I end up with a 12" beam exposed, that's unappealing to me. If I can push it up then there is only 4" exposed but that means I need some way to tie the top plate into the beam.
As far as using a different material, for some reason, GluLams not used and stocked in this part of the country, at least not at the lumberyards I use.
Everything is already spec'ed, post size (4x6) and blocking below that to carry the load to the foundation. The top plate is a 4x6, not the typical 2-2x4s so even an 8" I-beam would protrude below by a couple of inches if I left the top plate in. All the structure is in place and the wall above has temporary support. The only thing left is to get this beam in.
As everything is spec'ed, ask your Engineer what is required to put the beam in the studs above.

The S.E. should have requirements to install additional sheathing and shear hold-downs (to the foundation) on some 4' wide sections of the main house wall (for wall shear flow, and racking resistance).

Because you are removing 11' of continuity from that wall. As well as Simpson strapping at beam/top plate connections.

Inform the Building Inspector and give him the S.E.'s spec's, when he comes to inspect your house for safety.

Be safe, G
Thanks everyone, I was hoping to get this done today but that one spec is hanging me up. I thought this would be a business as usual type of issue and hoping Simpson has strong-tie application. I just had my SE size everything not design the connections. That was good enough for the building department and I didn't think of it until I tore everything apart and then proceeded with the head scratching. Anyway I'll have to quiz my guy on this.
If this is between the first and second floor, then how thick are the joist? I am saying to put the beam between the joist completely in the void, the finished ceiling would be flat.


Johnny Jackson
As John C. said, put the header into the floor space above. As I said, if the header is taller than the floor joists, by 4" (2x8's), cut out the flooring, bottom plate and 1-3/4" of the second floor wall studs. (to raise the header)

I had to use cs 16 (coil strap, 16 gauge thick), by 36" on each end of header to wall top plate, as per S.E. As an example.

If you call the S.E., here is the reference for Simpson:

Just enter in the letters he gives you in the box - top left. Be safe, G
I hope this picture helps. Don't pay any attention to the temporary rafters, the ledger attached to the house, or the leftover stud. I buttoned it up last fall to get through the winter. You can't see it but the wall is supported on the second floor.

The top plate that I want to cut out is a 4x6 and the top edge is on the same plane as the 2nd floor floor. The construction is a bit unusual in that way. You can see the new top plate that will bear the new joists. The old joists on the other side of the plate are 2x8 and run parallel.

There will floor space in the room above the sun room as well (the new master closet), so the choice would be either a flat ceiling on the first floor or a 4" step up into the walk-in closet. That's the reason I can't put this above the top plate. In either case the top plate must go.

Strapping is what I was thinking but I was concerned with lateral strength/stiffness.
I came up with an idea, if I sister a 2x6 along what would be left of the existing 4x6 top plate bridging into the new beam, I will be able to extend that well into beam by about 5' on both sides. I won't be able to make the sistered 2x6 one piece throughout because I need to get hanger somewhere around the middle of this beam to pick up a point load, but this should work.


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