Anyone have experience with flitch plates? Have a call into an engineer but this job may be too small or the existing setup may be too dicey for him to put his name to.
Situation is 4×10 (2 2×10) beam across a 11′ span, which I know is undersized by current code. The lovely thing is that some genius cut a notch right in the center of one of the 2x10s, 3″ wide and 2-1/2″ deep. In repitching a steam pipe that ran to the center of this beam, I discovered the steam pipe was 1-1/2″ out of pitch (!). Now maybe it wasn’t pitched right when it was installed….
So I’m trying to figure out how to fit a flitch plate in to beef this thing up, before I close up the floor. With sistering of joists there is about 13″ of joist bay to play with. There’s also a 2×4 ledger for joists (joists notched to sit on it). And a BX cable running through the SW corner of the remaining beam face. See pic. As you can see, space is tight for any fixes.
My thought is to put a steel plate over this space with holes drilled for screws as shown. I’m thinking of 2-1/2″ Timberlok screws since (a) I don’t have access to the other side of the beam without tearing holes in the kitchen ceiling and (b) Timberlok screws have impressive shear strength (about 230 libs) with smaller shank diameter than lags or carriage bolts (but does that mean they are more brittle?). I’m thinking of 1/8″ steel plate, covering the notch to pick up some of the compression the beam is feeling at that point. Should I beef up to 1/4″?
It has occurred to me to try to extend the plate down behind the ledger. This would require cutting a (20d?) nail holding the ledger, and my feeling is, First do no harm.
Any comments or advice gratefully accepted.
Edited 12/20/2005 10:53 am ET by Taylor
Replies
Here's a smaller revised version of the previous attachment.....
Notch on the top, correct?
Top of beam is in compression, so a tight fitting wood "plug" can also help.
That coupled w/ the 1/8" plate will probably handle it, but I do NOT KNOW WHAT LOADS ARE ON THE BEAM.
Have it double checked.
Since you only have 13" between the joists, the plug if it's snug enough will probably do more good than the plate. The big problem is transferring any load at all to such a small plate with just a few screws. A real Flitch plate runs the full length of the beam.
-- J.S.
The big problem is transferring any load at all to such a small plate with just a few screws. A real Flitch plate runs the full length of the beam.
Since it is a compression load, the plate will mostly be holding the plug in. Not in tension as a standard "flitch plate" beam.
My worry is that if I do not have enough fasteners, the wood will tear itself apart at the fastening points while it flexes but the plate doesn't.Probably something like this is best I can hope for:
My worry is that if I do not have enough fasteners, the wood will tear itself apart at the fastening points while it flexes but the plate doesn't.
It's not tearing apart now is it? Am I correct in assuming that this is an exisring flaw in a beam that has not "failed" so far?
The cut is on top. The notched area is in compression, so you need to fill the void. The compression loads will transfer through the plug, NOT the plate. Think of it this way, if you place a block of wood UNDER a column, how many screws do you need to hold it in place?
Adding the plug, and the plate is an improvement over what you have now. .The screws are for holding on the plate which keeps the plug in place.
Unless I am not understanding something, this should suffice.
The real super-important thing here is to make that plug snug. Jack up under the notch to relieve some of the load, just lift it a teensy, like 1/16 - 1/8". Make the plug a very hard driving fit. The plate is just sort of a nominal thing to retain the plug under extreme conditions, like an earthquake.
-- J.S.
Thanks can't jack up the beam, suspended DW ceiling under it (one of a series of bandaids to hide the sagging is my guess).
I feel a need to share this.I was following your advice, plugging a notch in the center of a beam. I punched a hole in the suspended DW ceiling below to put a post in and jack it up a little. And lookee here....The beam has a second notch, 4", on the bottom.Now I have to hastily add that it's a notch on either of the 2 2x10s making up a 4x10.Still.Time I think for a structural engineer.Anyone wanna buy a house?
I would use channel iron to manufacture a cover for the notch, top and side. Put a zerk fitting in it and use a throw-away grease gun to pump it full of expanding epoxy.
SamT