To any architects out there....
I am curious about the type of framing used for multi-storey homes
with ashlar stone masonry on the facades. I once read that large homes
with ashlar stone walls had to be balloon-framed. I think that it had
to do with the expansion and contraction of the frame. Is that true?
Or may such structures be constructed using platform framing?
Maybe he is thinking about the need to pick up the masonry veneer load every
2 floors, although the type of framing would not make any difference that I
can see. I wouldn't do it with a wood frame anyway.
The only other concern I can imagine is differential expansion vs. framing
shrinkage. Balloon shrinks less than western, but I'm not sure of the
difference in the coefficients of expansion for brick vs. stone....I would
think that brick was lower because of the internal voids but I don't think
the difference is large. Western framing shrinkage can easily reach 3/4" or
more once you get to three floors, depending on the usual variables.
Yes, with vertical strip windows between.
Shaped like this in section, with post tensioning.
Stepped to exterior. Bricks were 4x4x12 with semi-gloss glazed exterior.
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As I previously said, going over 2 stories may require the veneer to be
supported from the structure and a "soft" joint below the support. This is
precisely because of the expansion coefficient differences. All tiebacks
must allow for vertical movement.
An example: I was the architect on a team investigating leakage in a
Federally owned building in the Boston area that had been built in 1968 with
185' high x 16" thick post tensioned brick piers supported at the base, with
no weep holes, tied back to a concrete frame. The concrete frame shrank 3"
in 185', and the brick did not. The tiebacks (4x6x1/2" with 1.5" slots) were
torn apart in the upper half of the building, and the flashing at the top of
the brick was shredded. Why the detailers of this architect's wet dream did
not understand differential shrinkage I do not know. $2,500,000 in repairs
for bad detailing.
It was bizarre! We consulted a prestressed masonry expert from England who
was amazed. The building was by Edward Durell Stone and was to be a cutting
edge design for NASA. NASA was moved to Huston after Johnson became
president and 120 million in buildings being constructed were left empty.
Eventually the Dept of transportation occupied the buildings (It is a
campus) and the labs were converted to offices with an increased building
occupancy load. After 1974 the building managers cut off the dehumidifying
systems to save fuel. This caused a positive vapor pressure into the
building walls, trapping moisture behind the brick glazing. As this metro
area has over 500 freeze-thaw cycles per year, the brick faces began to pop,
a lot. Especially where the sun hit, so the falling brick slices would work
around the tower, with the only safe side being North. That's when we got
brought in. A very very interesting job. BTW we spot inspected the post
tensioning cables and ends and they were in great shape. Major solutions
were dehumidifying the building, new flashing, tie backs to the concrete,
drilling new weeps, and applying EFIS over the upper third of the tower.
This was done 14 years ago and 2 years ago the EIFS was in excellent
condition. I've always felt that I improved Stone's building appearance a
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