A.Christopher DeBlois,
P.E., an engineer with Palmer Engineering in
Chamblee, Ga., responds: Whenever there is a
design alternative, I generally recommend against
bolting a deck ledger board to brick veneer. I
prefer to provide independent support adjacent to
the house, usually with posts and beams. In many
cases that is impractical or undesirable, however,
so the deck gets bolted to the house.
The brick veneer on a house typically supports
its own weight and nothing else. The section of the
CABO One & Two Family Dwelling Code
on lintels states that “masonry veneer
shall not support any vertical loads other than the
dead load of the veneer above.” When
independent support is provided against the house
to support the deck, standard practice is to bolt
through the brick and the band at the house to
provide lateral stability for the deck. That way
the brick veneer is not forced to carry the weight
of the deck, so there is no violation of the
lintels section of the CABO code.
Although I’m against bolting the deck
ledger to or through the brick veneer, I recognize
that it’s not an uncommon detail and that
building officials often approve it. With that in
mind, here are some thoughts if you choose such an
approach:
I have heard the direct bolting of a deck ledger
to the house through the brick justified by arguing
that because the bolts extend to the house band,
the band will carry the deck weight. I disagree.
With a separation of several inches between the
back of the deck band and the face of the house
framing, the bolts will bend or rotate before the
weight is carried by the house framing. As soon as
that starts to happen, the bolts will bear on the
brick, and the veneer will be carrying the load.
The good news is that in most cases the brick has
substantial extra capacity. In fact, the capacity
of the bolt-to-brick component of this connection
will generally exceed the capacity of the bolt to
the deck ledger itself. As a result, the required
size and spacing of bolts are no different than for
typical wood-to-wood connections (see Practical
Engineering, 3/96). I strongly recommend
bolting all the way through the house band to
properly transfer forces pulling the deck away from
the house into the framing instead of into the
brick. Also, no lag bolts are allowed. And pay
careful attention to sealing bolt holes and
flashing against the house.
In some situations, requiring brick veneer to
support the weight of a deck is a bad idea
regardless of what local building officials allow.
Do not bolt the deck band to the brick veneer if
you suspect that there are no brick ties (all too
common on older houses), if the condition of the
brick and mortar is questionable, or if the brick
ledge or footing supporting the brick veneer is not
sound and stable.
Finally, a number of circumstances may warrant
contacting a structural engineer for guidance. If
there are large openings in the brick (for a bank
of full-height windows, for example), stresses in
the brick at the sides of these openings may be too
high to permit support of deck loads. Similarly, if
you need to support the end of a beam instead of
just a continuous, uniformly loaded band, special
support will be necessary.