I have used this type of detail several times in exactly
this condition. I have used LTT19 and 20 and at times the PAI8 and 24
ties. It has been successful with spacings at about 5' +/-. Spacing
has been determined by assuming a UDL pulling off the wall and thus anchoring
that to the floor/roof. Here in Canada we have to ensure that if the wall
is a firewall, then we make sure that the floor/roof can rotate in such a way
that the wall is not pulled down with any loss of floor/roof capacities. I
believe that these ties will not hamper such behaviours.
For joist parallel to the wall, I block out from the wall
at tie spacings for a distance that I calculate is necessary to distribute the
tie load into diaphragm shear. I add MST, or similar, straps
where necessary to extend the tie length.
The capacities available for the tie are determined by the
masonry pull-out capacity in most cases.
I have also applied them to the sides of roof and floor
truss/joists, but as close to the diaphragm as possible.
For retrofit cases that have space restrictions side-mounted
are probably the easier to install.
----- Original Message -----
Sent: Monday, June 25, 2001 9:31 PM
Subject: Tension Tie of floor framing to
know this has been discussed a number of times, but I have not had time to
search the archives. I am connecting a wood framed mezzanine to an 8-inch
reinforced masonry wall via a 3x ledger. The CMU wall is reinforced with solid
grouted cavities (as confirmed by the contractor). I have to make the
tensile tie of the framing to the wall and to avoid cross-grain bending of the
3x ledger (cross-grain failure).
Simpson shows an LTT19 nailed to the
top of the joist and secured with a 5/8" threaded rod into a concrete wall
with their ET Epoxy anchor. While Simpson provides values for tension in
masonry, their literature for the LTT anchor only shows its use in
Considering this is a retrofit, it might be difficult to
drill the hole
for the anchor because the "leg" of the LTT is short and the
of the hole too close to the sheathing to get a drill bit
place. This is my impression and it could be wrong. Has
experience in this type of connection?
Can I use the LTT
flush nailed to the side of the joist and drilled
through the ledger to
secure into the masonry with an epoxy anchor? I'm
sure this must be a
fairly common detail and would appreciate it if I
can obtain a copy of a
detail from another office familiar with this
Only 7-feet of diaphragm tributary is connected
the the wall - the rest
is bearing on interior stud bearing walls which are
designed for shear.
The length of the ledger at the edge of the diaphragm
is only 14-feet on
one wall and about 30-feet on the other wall (one side
is open, the
fourth side is a wood stud wall). The masonry wall is 8"
pilasters at 20-feet on center - the mezzanine is not connected
roof. The 14-foot ledger is bolted to a wall that is about 80-feet
and the 30-foot ledger connected to a cmu wall 160 feet long. The
contributed by the tributary area of the mezzanine connected to
masonry wall is much less than 2% of the existing demand to be
insignificant. The CMU walls are virtually solid (about 80% solid
long direction and 100% in the shorter direction).
lateral contribution of the mezzanine is insignificant, I
still have to
consider the effect of the mezz to pound the wall if it
Therefore, I need to make the tension tie which I believe
still has to be
equivalent to 200-plf or 30% of the tributary wall area
(at least it was in
past codes). Can anyone clarify this for me to save
me a few minutes of
searching the code?
Any suggestions for a tie connection would be
Dennis S. Wish, PE
(208) 361-5447 E-Fax