Basement Bearing Wall Removal

[Sokka10]

Hello gals and gents, I'm working on a basement remodel which I haven't done much of in the past. We're replacing a bearing wall with a new beam. Pretty simple. However, as I was working through this I started to consider the connections of the new 6x6 posts to the foundation walls. One of these posts will only be about 4' tall and then sit on the existing sill plate. The post on the other side will be about 7' tall and then sit on a foundation. I'm attaching the beam to the posts with some simpson connectors. How would you go about the connections of the posts to the foundation wall? Just toenails? Some kind of mechanical connector? I guess I'm just worried about lateral movement in the beam from seismic forces. Since the existing floor joists (with floor sheathing on top) will tie into the beam do I need to worry about lateral movement in the beam? Am I overthinking this?

 

[phamENG]

Where the short post hits the sole plate, toe nails are probably fine. Where it hits the foundation...unless it's wood toenails might be a bit tough. I'd opt for a standoff post base to keep the wood off the ground/concrete and give you a positive connection.

Your post cap should be able to restrain the beam ends from rotating, so then you just have to either design the beam as unbraced (usually works) or fasten it to the floor joists to brace the top edge.

A side note - when I do designs in existing houses, I usually have the contractor upgrade things that we're touching to meet current code. So in this case, I would require blocking of the existing joists over the new beam unless I could convince myself the joists were already adequately restrained there.

 

[skeletron]

Maybe there is something missing on your sketch. I'm assuming that both new posts are within walls and not freestanding.

Simpson makes the BC6 or UB66 post base that you could anchor to existing foundation with. That might work for your arrangement instead of toenailing. Simpson also makes a bunch of column caps that may work for your situation.

As for the lateral: it depends on how the whole system is setup to provide any useful commentary. Yes, I think a beam replacing a wall should be connected for lateral load resistance (ie. positive connection as per phamENG's comment above). No, I don't think you necessarily connect it to act like a frame unless the whole system is dictating that.

 

[Sokka10]

Thanks for the responses.

phamENG, yes on the right end of the beam I'm not sure whether there is a plate on the foundation or not. Neglected to draw that in. I'm assuming there is a plate because that currently is a framed wall between stairs that go up and down. Won't know until the contractor opens it up.

skeletron, you assume correctly, both posts are in stud walls. I was too lazy to note that on my sketch. I'd rather go with toenails at the base but I'm not sure that would be a completely sound connection shear-wise. At the same time post bases seem excessive...

 

[phamENG]

Sokka10 - for stability, you want your top and bottom connections to have a lateral capacity of at least 1% of your maximum column load, but maybe more if you have significant seismic loading. Generally speaking, interior walls are also designed for a 5psf lateral load if not exposed to exterior wind pressures (normally open door - not exactly common in houses...) or higher seismic loads. So I'd take the worst of those scenarios and design the top and bottom connections for those. If toenails work, great. If not, a simple post base isn't all that expensive.

 

[JLNJ]

Do you have any soil thrust or other lateral loads which the wall might be taking in its current state?

 

[ProgrammingPE]

Just a few thoughts:
[ul]
[li]Connections must be made between the existing joists and the new beam. Since nothing is framing into the sides of the beam, this is the only way that the frame will be braced out of plane.[/li]
[li]Blocking should be provided for the existing joists since this is a bearing point (nothing has changed here from the previous condition with the wall, but it is still a good idea).[/li]
[li]If the beam is deep, the post top connection should be somewhat substantial (not just a an 18 gage plate with just enough room to add a few nails) since you don't want this connection to rotate out of plane since there's nothing framing into the sides of the beam.[/li]
[li]A standoff post connection at the base is probably worthwhile. It'll be significantly stronger than toe nails, they're not very expensive, and the existing sill plate is probably a 4x which is smaller than your 6x6 post.[/li]
[li]You're removing a bearing wall which may have contributed to the lateral system. This isn't frequently an issue for residential depending on your region, but just be aware.[/li]
[/ul]

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