Every
so often, perhaps once every 50 years, an opportunity appears for
an industry to surge ahead at a pace which boosts sales at a surprising,
unexpected rate.
There are very positive
signs around today that the ceramic tile industry is moving into
such an opportunity. It has
been gradually
building up for several years and ready to become a reality ... an
explosive opportunity for growth to those who are prepared and aggressive.
Tile
contractors, distributors and manufacturers of tile and related products
should
commence research, training and marketing plans if they plan to
profit from this new frontier.
The new market
is in: prefabricated,
exterior tile panels framed with lightweight steel studs.
Although the basic concept is not truly new, this system
has now become economically feasible due to recent, cost-reducing production line methods
of making lightweight steel studs and other elements in the system.
Thirty years ago, the con cept was first used on a Tishman high rise office building in Los Angeles.
Although a highly publicized
and successful project, steel studs and other elements were then customformed which priced the system out of the market for that time. Today, the situation
is reversed. Prefab panels are now more competitive (often by a big margin)
than glass or aluminum curtain wall, precast concrete, masonry, etc.
ADVANTAGES OF PREFAB
Prefabricated panels installed over gypsum sheathing, framed with lightweight
steel studs, comprise a new system for high-rise exterior walls where permanent architectural beauty, surprising economy and most efficient scheduling are desirable or necessary.
Although steel stud prefabricated buildings have a long and successful history, this marks the first time that a system has been available nationally using exterior facing of the most prestigious and permanent material
... ceramic tile. The lightweight,panels are assembled and finished indoors then transported to the j ob-site for erection with rooftop rigging or other lightweight lifting gear. Costly scaffolding is eliminated except on lower floors when hand-setting of tiles may be advantageous.
From initial design stages through final installation, technical services are available without obligation to architects and contractors for consultation, drawings and specifications.
In brief, prefabricated ceramic tile panels on steel stud framing offer the following advantages:
- Eliminates tons of costly
deadload in design and requires less structural mass since panels weigh approximately 80% less than brick or pre-cast concrete.
- Significantly less expensive than glass or aluminum curtain walls ... superior insulation capability, more energy efficient.
- Eliminates costly scaffolding ... panels are hoisted by lightweight lifting gear such as rooftop rigging and welded into position from the inside of the structure.
- Panel cavities
provide a chase for pipes and wiring along exterior walls,
for faster, easier and more economical installation.
- Exterior
ceramic surface is virtually maintenance-free; requires no painting, acid-cleaning, or renovation.
- Factory
supervision and quality control assures utmost accuracy, closer tolerances and more consistent
results.
- Rain,
snow and freezing temperatures do not delay completion schedules
since panels are constructed in enclosed building; Superior
resistance to wet weather compared to other prefabricated
panels.
- Tile exteriors
are permanent and non-fading and frostproof ... aesthetic
additions to any community, forever.
- Exclusive
keyback ridges on some ceramic tiles permanently lock tiles
into portland cement mortar in panels for superior margin
of safety.
THE
MARKET POTENTIAL
According to some respected construction
industry executives, prefab the panels represent one of
the most exciting and explosive growth potentials
for ceramic tile in the next decade. It's a concept, they
believe, whose time has come. According
to latest F. W. Dodge Statistics, non-residential construction (office buildings, commercial stores, schools,
hospitals and manufacturing) construction in 1979 was almost $50 billion dollars. Exterior walls for these
buildings consume 3-11% of the total construction costs
(for brick, block, stucco, curtain wall glass
or aluminum, etc.) which boils down to a conservative $2.5
billion dollar market each year. Up to now, ceramic
tile has captured an insignificant share of this potential
due to various reasons (scaffolding costs, weather
limitations, etc.) but now the situation has changed 180
degrees.
If
tile can capture 5% of this exterior market, the potential
is $250 million per year. Even at a conservative
2%, the volume will be $100 million per year which is
more than 10% of the total tile market in the1979
year for the United States.
Obviously, prefab tile exteriors are not for every office building, hospital,
school or other building. However, many, many contracts now going to
curtainwall, concrete or masonry would be excellent prospects for the
prefab tile system for economy reasons alone. Block and brick, for
example, do about 10 times the sales of tile according to the U. S.
Department of Commerce. Glass and aluminum curtainwall (now on a downhill
trend due to poor insulation
qualities) cost at least 30% more than installed prefab
the panels.
PIONEER PROJECT DENVER,
COLORADO
In
September, 1980, the first modern-day high-rise with prefabricated
ceramic tile panels was completed in Denver, Colorado ... the stunning 12-story Lincoln Court Building.
The Lincoln Court office building
was designed by McMorran Obermeier Goss Bershof Architects
(better known as "McOG") and erected by Turner Construction Co., general contractor. Tile was laid by
Ace Tile & Terrazzo Company in lightweight steel stud panels made by John Burke, Inc. The
tile is Gail Unglazed Red Range Brickplate with brown and black flashing to provide
iridescent blending of colors within each panel. The keyback ridge design in Gail Brickplate locks the
tile
permanently into the mortar bed for an extra margin of safety.
FABRICATION AND
ATTACHMENT OF PANELS
All panels were assembled and finished indoors,
a great convenience in Denver's winter weather, then transported to the job site. While other
projects may require different arrangements of steel, backing and attachments,
the Denver
panels demonstrate the basic idea.
They
were framed by 16-gauge punched steel Cee studs 6" wide, on 24" centers, and rest
on tracks of unpunched 18-gauge steel. Each roughly-two-inch-thick
panel is backed by 1/2" asphalt impregnated gypsum sheathing (core treated) on which is placed self-furring
expanded
metal lath with asphalt treated
paper back. These are screwed to the studs with self-tapping
screws over washers. This is followed by two 3/e" coats
of portland cement plaster, latex modified portland cement
bond coat and then the tile.
Crucial to the success of this new system is the method of affixing the panels
to the
structure of the building, which has a steel frame and poured-in-place
concrete floors.
Three-foot-long
2" x 2" x 3/16" clip angles were welded vertically to the spandrel beams all the way around the
building, including corners. The steel studs of the tile panels are welded to
these angles, making a sturdy and permanent installation. Glass fiber insulating
batts, 6" thick,
are placed between the studs.
READILY AVAILABLE MATERIALS
The basic
elements of the newstyle walls are light gauge steel studding:
and joists. These are practically off-the-shelf items available throughout the country from many manufacturers-such
as Bostwick, Inryco/Milcor, U. S. Gypsum, U. S. Steel and others. Assembling
and erecting of the steel framing can best be done by journeymen lathers rather
than iron-workers or carpenters. The remaining materials: asphalt impregnated gypsum sheathing, self-furring
lath,
cement, gypsum wallboard and the are also available everywhere.
Different methods of anchoring the panels to the building may be devised according
to need, as long as the whole affair conforms to local building codes.
In addition to code
requirements, it is advisable to ascertain allowable spans
from the supplier of the steel framing as protection against
wind and seismic overloading.
It cannot
be emphasized too strongly that fabrication and fastenings
must be of top quality for permanent reliability. Also, the tile selected must be of a frostproof type that
resists local weather conditions.
The very
nature of tile panel construction helps induce the highest standards of quality control. Since panels
are made under shelter, they can be
fabricated with extreme accuracy, closer tolerances and more consistent results. For the same reason, completion
schedules are not delayed by rain, snow and freezing.
At the construction site, this type of framing facilitates rapid formation of
window and door headers. It also tends to distribute and dissipate
strains throughout the entire structure. It is, however, recommended
that the architect and design engineer consult with the panel prefabricator
right from the
start.
FIRE RESISTANCE
The various
components of prefabricated exterior tile panels are made of non-combustible
materials and generally carry a flame spread and smoke density rating of
zero. After fire rated gypsum wallboard is attached to the interior flange
of the steel stud framing, most building codes qualify the wall as a one-hour
fire-rated system.
TEMPERATURE CYCLING
TESTS
To prove that
the Gail Brickplate panels used on the Lincoln Court Building were durable
under adverse conditions, tests were conducted by an independent testing
construction research laboratory in 1980, which subjected a panel to severe
temperature changes and freeze-thaw conditions to simulate extreme weather
conditions.
The test panel was constructed identically to the prefabricated wall panels used
on
the Lincoln Court Building in Denver, Colorado. The exterior surface of the panel was subjected to 150 heating and cooling cycles
alternating from 25 degrees F to 145 degrees F with each temperature extreme
held for 15
minutes.
The panel was also subjected to twelve freeze-thaw cycles in which the panel
was covered with 1/4 inch of water and frozen to -20 degrees R The average cycle time was four
hours with
complete thawing after each freezing phase.
The laboratory reported that there was no evidence of any, damage or cracking
resulting from
these tests.
A final word: All reasonable clearance between panels and structural members
for adjustments in vertical, horizontal and rotational positioning.
The use of metal shims or other adjusting devices to align panels is
recommended.
While details may differ from one locality to another, these easy-toerect prefabricated
tile panel walls offer the multiple advantages of lightweight, economy
and maintenance-free permanent beauty.
SOURCES OF
INFORMATION
Already some of the more aggressive major companies
have been planning and preparing for the future growth of prefab tile panels.
Probably the most experienced is Gail Ceramics, Orange, California, which supplied
the tile for the Lincoln Court Building in Denver and worked closely with the
architects. Gail has prepared excellent technical information, brochures and
slide presentations on the system and also has an architectural consultant on
staff to answer questions and assist in problem solving, estimating and detailing.
Since Gail was the first to be involved in a major prefab job, their experience
is also advantageous to a firm anxious to learn and expand. Moreover, Gail has
a special "keyback ridge" on the backside of their tile which serves as a sales lock-in advantage when
an architect or engineer is worried about the tiles falling five floors from
the
surface of the structure.
Huntington-Pacific has also been active in this market and has produced a slide
presentation on the system which has been shown at industry meetings
in recent months.
For counsel on the installation of tile over the sheathing, the Lathing Bureau
has
information available.
In one year, dozens of companies will be jumping on the bandwagon but only a
few of the better financed firms are prepared right now to help without
obligation.
SUMMARY
The tile industry is on the threshold
of a major breakthrough for growth. Not every contractor is geared for
this work: it is for the medium and big operations. But, the potential
looks very bright. Aggressiveness in learning sales, training and risk-taking
can pay
big dividends for these firms.
FURRING & LATHING INFORMATION BUREAU
PANELIZING
EXTERIOR WALLS WITH STEEL STUDS, LATH, PORTLAND CEMENT PLASTER AND CERAMIC
TILE
INTRODUCTION
Architects and builders, wanting to reduce dead load, construction
time and costs, are more frequently utilizing light gauge steel stud
framed panels with any of several different finish materials to construct
exterior walls on their building. Tile and masonry veneer are two of
the most desirable finish materials designers would like to use on their
buildings; however, they are concerned with the cost.
Remarkable cost savings are possible when the steel stud panels with a tile finish
are fabricated
off the job site, then shipped to the job and hoisted in place. The panels are simply but securely
welded to the structural frame of
the building.
TERMINOLOGY
There
are a few terms and definitions which should be understood to be familiar
with prefabricated
tile panel construction.
- STEEL
STUDS AND TRACKS
Steel studs and tracks are roll formed sections
usually fabricated from metal in thicknesses of 16, 18, 20 or 25 gauge. They
may be fabricated from galvanized
steel or are available painted with rust inhibitive paint. Steel studs and tracks
are available
in widths of 2-1/2", 3-1/4", 3-1/2", 3-5/8", 4" and 6" and in lengths cut to order,
up to 20' - 30'.
 
A. STUDS
There are over a half a hundred different types,
sizes and gauges of steel studs, so care should be taken to select the most appropriate
one for any particular application.
The webs of steel studs typically contain punchouts
through which electrical and mechanical
lines can be run. The punchouts also serve to reduce the
weight of the sections.
B. RUNNER
TRACKS
Runner tracks, which secure the
studs at the top and bottoms of panels, do not have punched webs. They are fabricated
slightly larger than the stud width in order to provide secure attachment top
and bottom.
- GYPSUM
SHEATHING
In order to assure flattest
panels with adequate racking strength, 1/2" thick fire resistant gypsum sheathing is screwed to the steel stud framing with
self tapping screws prior to lath and plaster application.
Gypsum sheathing has
a water resistant gypsum core encased in specially treated brown
water repellent paper on both sides and long edges. It is not a
vapor barrier!
Available 24" wide
with V-shaped T & G long edges, normally applied horizontally with tongue up. Also available 48" wide with square edges for vertical application.
-
CASING
BEADS (Plaster stops)
Fabricated from 26 gauge galvanized
steel, casing beads are available in 1/2", 3/4", 7/8",
1" and 1-1/4" sizes to accomodate different thicknesses
of plaster and finish materials. Best quality panels are produced
when 1-1/4" casing beads are installed to the framework first, then the sheathing, lath and plaster is installed. Casing beads are also available
on special
order in zinc alloy and stainless steel.
- PAPER
BACKED, SELF-FURRED METAL LATH
Lath for Portland cement
plaster can be expanded metal, woven wire (chicken wire) or welded
wire fabric. All three are available with a self-furring feature
and with factory applied paper backing.
The building codes allow
for the elimination of paper backing when lath is installed over
a solid backing like gypsum sheathing but best results are achieved
when the weather resistant paper is included.
There are two grades
of building paper approved for use as a weather resistant underlayment
for exterior plaster. Both are covered by Federal Specification
UU-B-790, Type I, Grade B or Grade D. The difference between the
two grades is in the allowable moisture permeability.
- FORCES
AND STRESSES
The exterior skin
of any building is subject to many different forces, from wind, earthquakes,
framing movement, thermal fluctuations and vibrations. Whenever a force
acts on a body, there is an accompanying change in size or shape of the
body. These forces cause the wall materials to bend, deflect, deform
or compress, sometimes to the point of failure. Any material's ability
to withstand these forces depends on the strength, stiffness and method
of installation.
A. DEFLECTION
Deflection is a typical physical action. It is that deformation
which occurs from bending forces perpendicular to the panel face. Brittle
materials like plaster and tile may crack or delaminate when the matrix
deflects as much as 1/360 of the overall
span.
Deflection ,in steel stud framed
panels can be reduced several different ways;
1. Use larger stud. (6" stud
instead of 4")
2. Use stud of heavier gauge. (16 gauge instead
of 18 gauge)
3. Decrease stud spacing. (24" to 16" or 16" to 12")
4. Reduce the height of the panel.
B. RACKING
Racking is a physical action resulting
from earthquakes, framing movement or forces in the direction of the plane of
the panel.
Sheathing, lath, wallboard, and
other collateral materials properly attached to studs afford a small degree of racking ,resistance, Diagonal bracing welded to every intersecting stud provides
the best values.
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