Cutting (and hanging) 100+ year old joists
We own a 130 year old, 2-story brick Victorian with a stone/rubble foundation. We’re planning on replacing the main wood support beam in the basement (currently supported by 7 lally jack posts) with a steel beam. The current beam is almost 30′ long…the joists above are continuous and run about 20′ across.
I’ve had a structural engineer do the calculations for beam and column size (W8x24) with the option of cutting the continuous joists, placing the beam flush to the floor above, and hanging the joists off the new steel beam.
My question is….how realistic / wise / prudent is it to cut these joists so the new beam sits up flush against the floor above? I’m not concerned with existing utilities / ductwork.
As I see it:
Pros: The most primary advantage is gaining the headroom. It would be really nice to have it flush with the joists and one smooth ceiling finish in our basement.
Cons: Cutting 130+ year old joists just makes me hesitant …It makes me think: “these have existed for such a long time just as they are…don’t mess with what works!”
What has been your experience? Have you cut continuous joists in order to rehang them from a new beam? How concerned should I be? Or is this a relatively straightforward process?
Thanks!
Replies
What would the ceiling height be in both cases? If you make the beam flush, what happens to the duct?
I will already be rerouting the ductwork, which is why I’m not concerned by that.
Current ceiling height (unfinished) is just shy of 7’ at bottom of joists....around 6’2” at underside of beam.
I’ve seen lots of finished projects where homeowners open a load-bearing wall and then move a beam flush into the joists...but not many details on the particulars of cutting the joists and hanging them off the new beam (whether steel or LVL).
Has anyone else seen anything like this?
Build a false wall on each side of the beam location but far enough away to have room to lift the beam. If it's an I beam fill the space between the flanges with wood 4x would be best. Bolt through the beam, but you don't need too many bolts because the bottom flange will support the wood. Saw the joists to where the beam will just fit in the space between the ends. You'll need to use a recripocating saw for most of the cutting. Be sure to use a very sharp blade. You might go through quite a few. Jack the beam into place and install the columns. Attach joist hangers to the wood on the sides of the beam for each joist. Remove the false work.
a. does NOT appear to be 'continuous' jioist, just butted withteh plywood scabs, so cut has no negatives. Use Mike's technique or similar.
Alternately, if the joist TRULY are continuous (and not 2 joist butted over the girder) an alternative for adding 4" of headroom would be for your engineer to specify 2 each 4 ro 5" deep box beams. Space them offset from the center. A LOT less work than cutting existing joists
If there is a new post, make sure of the footing, you many have to pour new footing even for the 8W24.