The Simspson SDS 1/4 x 2 seem like a good choice. BTW, the holes for
the screws need to be a hair over 1/4", I had some holes punched at
1/4" exactly and had to ream them out a little to allow the screws to
So the screws are there are to transfer the shear load to allow
unitary action and then as you say to keep the plate from buckling out
of plane. How does one design the fastener pattern for each of these
purposes? Obviously for the buckling, the plate thickness is
important. So the fastener pattern will determine the answer to
another question raised, what is the minimum plate thickness?
Looks good to me: E_steel / E_oak is about 18, and 2" / (1/4") = 8, so
a full height steel side member is 2.25 times as stiff.
You've got a couple of things going on depending on how the plate
isadded & whether is bears on the joist support.
Like I said in my post to Steve, I'm really not sure how I'd calc the
screw pattern but two rows 12"oc staggered seemed reasonable for 1/4"
plate. Since the plate is full depth we're not making a "composite"
beam like a T-beam or other assymetric shape, the fastener schedule
need not be as dense as for those types of apps.
So I'm thinking all we need to consdier is the overall load path.
Load goes into the "joist & steel plate system" over the entire span.
If the plate doesn't bear on the joist support (wall top plate?) then
we need to take the collected load out of the plate & back into the
joist at the end of the plate. And this would require a heavy screw
pattern If it does bear, we need to provide a bearing plate so that
side plate doesn't cut into the top plate.
Here's where I really like to bounce this concept of someone who can
poke holes in my ideas. I'm not totally sure what the screws pattern
needs to look like near the ends IF the steel plate doesn't bear on
the joist support. If it does, I pretty sure that the 2 rows- 12"oc
staggered is fine.
What I'm say is that if the steel side plate completely mimics the
joist then the screw pattern is less important. If side plate doesn't
span & bear as the joist does....then the screw pattern is more
Insufficient data- what problem are you trying to solve? Is joist
damaged, is floor bouncy or sagging, are you planning to add a grand
piano and a waterbed above, or what? What you are describing is
gusseting, not sistering, and is usually only used on a damaged joist
that would be a PITA to switch out or sister, which means setting
another real joist right beside it, going all the way out to where the
ends of the joist rest on the sill plate, crossbeams, or whatever.
Gusseting to stiffen a joist is usually done with metal plates, by the
way, through-bolted through the joist. If the joist is sagging, you have
to jack things back into square before you start. If it is just a bouncy
floor, adding or replacing the 'X' braces between the joists may be all
that is needed. Traditional cure for a too-long span is to add a beam at
the midpoint, held up by screw columns, or grafted into the structure of
the basement or lower-floor walls.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.