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Hot Topics: Sister Floor Joist

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Original Post: Sister Floor Joist

Spinny24 Member

I have a second floor beam in other stories originally cut to accommodate a brick chimney. I removed the chimney and need a sister in the beam. Floor joists are redwood full dimension 2 "x8" x1

4 "at 16" centers. Do I need full-length, partial-length, single-sided or single-sided sister? What type of wood, or maybe Microllam LLV?

 a patched wooden beam from below

XSleeper Group moderator

Is it a loft above the beams? It makes a difference, because your beams are currently over-arched. [19659006] Spinny24 Thread Starter

Not the wind floor.This is the second floor of a built in 1892 in Northern California.

XSleeper Group Moderator

Yikes. stick to 8 "or can you use 9 1/2"? A single 9 1/2 "LVL sister on one side would do it. Yes, the entire span (from the bearing wall to the bearing wall).

Build a temporary wall under the broken beam and look it up until it is straight, or even slightly crested. PL these beams and underfloor when you are sure it will fit. Then insert the LVL and crown it a little with a jack to match when you attach everything together.

Spinny24 Thread Starter

Cannot go 9 1/2 ". Had to raise the entire second floor which is about 2000 square meters. Even with the cutout in the beam, the beam is still completely flat after 100 The home is designed with balloon framing.

XSleeper Group Moderator

Well, you will probably need to get a 9 1/2 "LVL and rip it to 8" then. I assumed it would was ballooning in a house so old. You just need the sister pins under the ends of the LVL.

Fantastic, it's still level. It says something about the old growth timber – far superior to the garbage they sell us today.

Spinny24 Thread Starter

Thanks, what's great is the living room with the same framing dimension is 18 feet wide and 18 feet long.

Added a few extra p hotos by the studs at each end. the studs should j ag sister? A double has cross support at the top.

 wooden floor joists from below

 a wooden floor joist from below

XSleeper – [1945900] ] In the right photo it looks like you want to do it on the left side.

On the left photo it looks like you would have to put out the entire right side 1 1/2 "so that your LVL slides next to that stud on the right, but will that cross support be in the way if you do?" 19659006] Spinny24 Thread Starter

What about boxing out the cut out section to the adjacent beams?

XSleeper Group moderator

You can, but it is asking a lot because they are already overstated by today's standards. Since you say that everything is still straight and even despite the hack job, it would probably be easy to do.

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