FACILITIES - THE BRANCHES
EXTERIOR DESIGN AND BUILDING IMAGE
IV - 49
EXTERIOR DESIGN AND BUILDING IMAGE
An interesting and unusual aspect of the Dallas Public Library branch system is that each of its
twenty-two locations has its own distinctive exterior design expression. However, there are some
common themes in plan organization that are expressed in the building form and exterior treatment
that generally reflect the period in which they were constructed. The exterior design guidelines of
the Master Plan were developed to avoid the problems and build upon the successes identified at
the present branch locations.
Branches built during the 1960's and early 1970's
Most of these older facilities such as Walnut Hill, Hampton-Illinois, Casa View, Polk Wisdom and
Audelia Road are simple rectangular shaped structures with low-slung flat roofs. These are unassuming buildings that don't stand out in their surrounding environment, especially in a busy retail
strip.
The exterior designs of these branches feature facades with either large expanses of storefront glazing or solid masonry. The glazed facades usually face a public street, which is good. Unfortunately
the solid walls block views to parking areas.
Branches built during the 1970's and 80's
Many of these branches introduced new design features to increase their visual impact and attractiveness. Though very similar in plan to the branches of the 1960's, Dallas West mixed smaller
alternating sections of glass and solid walls at each façade of the building, resulting in a more accessible and inviting appearance. Lakewood retained the simple shape and low roofline but utilized
high quality materials such as copper mansard roofs with deep overhangs at its windows, attractive
brick walls, lush landscaping and bold exterior sculpture.
Branches such as Fretz Park, Highland Hills and Skyline employed complex plan configurations
and higher, more distinctive rooflines. Of these, Skyline has the most successful exterior design
because it is compatible in scale and design expression to its park-like surroundings. In contrast,
Fretz Park faces its parking lot and public entrance with large expanses of almost windowless brick
walls at its meeting room, staff room and Children's wing.
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FACILITIES - THE BRANCHES
RECOMMENDATIONS FOR EXTERIOR DESIGN
Branches built in the mid to late 1990's
These branches are even more varied in form and are successful in holding their own as special
buildings in their neighborhoods. Mountain Creek combines a complex shaped floor plan with a
bold sloped roofline. Kleberg-Rylie has a less complex plan and a high and broadly arching
roofline over its reading rooms. Renner Frankford has an even simpler plan but numerous gable
and contrasting flat roof forms. Oak Lawn has a simple rectangular plan and roofline but varied
wall and window treatments on each facade. North Oak Cliff also has a simple rectangular plan,
but has a bold gable skylight that runs like a tall central spine from the drop-off at its entry to the
opposite end of the building.
The strongest point of these newer designs is their distinctive higher rooflines. Given the flat topography and long views common in Dallas, this makes them more visible and recognizable. These
high roofs also create a feeling of spaciousness and light within the central public service areas of
these branches. The weakest part of the latest designs is that most have solid, almost windowless
entry facades, which create safety and security problems. This issue is most evident at the Skillman
Southwestern, Kleberg-Rylie and Renner Frankford branches.
RECOMMENDATIONS FOR EXTERIOR DESIGN
The Dallas Library does not wish to create a common design expression for its branches, but rather
to provide design guidance for dealing with common issues and for creating high quality designs
at all branch locations.
Plan Configuration
Library programs fit best in simple rectangular spaces, especially the stack areas. The use of varied building massing, to create wings for example, is generally most successful to delineate and
draw distinction between major program groupings such as the meeting room complex, the staff
room and other supporting core facilities, and the primary public service areas. Excessive gratuitous use of projections and corners in a design can reduce efficiency, increase costs and create
blind spots both within and outside the facility.
FACILITIES - THE BRANCHES
RECOMMENDATIONS FOR EXTERIOR DESIGN
IV - 51
Rooflines
Given the size of a single story branch, and the relative simplicity of its plan, the use of interesting
roofline forms and attractive roofing materials is recommended as a way to create a distinctive
appearance that will mark a branch as a landmark in its community. Bold yet simple designs are
best to control costs and avoid potential leaks. Varying roof heights and contrasting flat and sloped
roof forms are strategies that have been successfully employed in some of Dallas Public Library's
latest branches.
Skylights can be used but only in limited applications due to concerns about heat gain, leaking and
glare. Raised roof sections with clerestory windows, window monitors or dormers are better alternatives for creating higher spaces and bringing added natural light to center of the branch.
Regardless of the system chosen for introducing natural light from overhead, quality materials and
careful detailing is required, especially at flashing conditions, to avoid leaks.
Walls and Windows
Light to medium tone brick masonry or similar high quality, durable low maintenance material such
as "real" stucco is recommended. These materials are appropriate for this region. They will minimize heat gain, and tend to increase the apparent size and visibility of the branch, especially in contrast to shaded landscaped areas. Deep roof overhangs and/or solar louvers or awnings are recommended at southern and western exposures to control glare and excess heat gain. These will also
create bold shade and shadow lines and enhance the transparency of windows.
Wherever possible each facade should have at least some glazed areas to improve security and create a feeling of accessibility and welcome. This is especially important at the entry façade. Lightly
tinted or low reflectance glazing is recommended to maintain transparency here and in other areas
where the goal is to showcase the interior of the library and increase awareness of its resources to
the community. If darker tinted glass is used in these areas its effects should be offset with external shading devices and interior accent lighting of surfaces and objects near the window surface.
This is a design strategy often used for storefront display windows.
Storefront and window frames should be of durable low maintenance anodized or Kynar painted
aluminum. The color and value (lightness or darkness) of these frames should be used to compliment exterior walls and add interest to the design. Clerestory and/or monitor windows should be
of curtain wall construction to avoid the potential of severe damage from overhead leaks.
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FACILITIES - THE BRANCHES
BUILDING SHELL TECHNICAL GUIDELINES
BUILDING SHELL TECHNICAL GUIDELINES
The construction industry is a dynamic, ever changing industry with materials, products and
processes constantly evolving in response to market and environmental demands. Guidelines for
quality construction must take into consideration the existence of proven building techniques and
materials while being flexible enough to adapt to the evolving industry process. Even the use of
the best construction design, materials and techniques requires a process for maintaining the building investment.
Glazing - includes transparent or opaque glass or plastic materials and opaque panels set into a system designed to hold those materials in a secured or weather tight condition.
•
Selection of materials should be based on durability, safety, security, vandalism
and energy conservation.
•
Clerestory windows should have lightly tinted, insulating, security glass to
avoid condensation problems which occur when heat rises in ceiling spaces.
•
Avoid the use of translucent, insulated fiberglass which have a short life-span.
•
Control light transmission and heat gain with site location and architectural
elements. Limit the use of glass on southern and southwest exposures.
•
Use lightly tinted, heat absorbing, low-E , insulating glass on exposed southern
and southwest exposures.
Skylights
•
•
When thoughtfully used, skylights can be an important source of improved
ambient lighting. Care must be taken to provide units that are insulated and have
heat reducing glazing. Curbs should always be well elevated above the roof
surface and should be insulated, and properly flashed.
In order to limit condensation on the glazing material, avoid the use of light wells
which trap warm air or provide a means of air movement with additional return
or supply air grills.
FACILITIES - THE BRANCHES
BUILDING SHELL TECHNICAL GUIDELINES
IV - 53
Roofing
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Materials should be selected on the basis of longevity and compatibility with the
majority of existing library roofing systems.
For low-slope roofs, conventional four-ply, built-up fiberglass roof systems are
easier to repair than single-ply, non-asphalt based systems.
Low slope single ply and foamed-in-place roof systems require a great deal of
technical skill in application and repair and should be avoided.
Where possible, avoid the installation of interior roof drains and always have an
over-flow drain or scupper.
Flashings associated with roofing must be compatible with the roofing product
and should be able to be soldered if the material is metal. Painted coated
flashings that rely entirely on sealants for waterproof connections should be
avoided.
High sloped roofs should have coverings that resist wind, fire and hail damage
and have at least a 20 year life cycle. Avoid the installation of gutters on roofs at
sites with adjacent trees.
Typical manufacturer's roof guarantees are written to protect their interest in lieu
of that of the owner. If other than the standard one or two year guarantee is
desired, it should be written by the owner's representative.
Exterior Wall Materials
•
Most buildings should be constructed with a hard surface exterior material such
as stone or brick and installed as a veneer to allow for interior drainage to the
exterior if the veneer or flashings fail for some reason.
•
Select proven materials based on long life expectancy and attach them to a stiff
back-up wall with anchors designed to resist horizontal wind loading and cavity
corrosion.
•
Avoid construction of exterior walls with directly attached exterior finish. Most
soils in the Dallas area are expansive and movement in foundations is difficult to
control. Stucco directly applied to masonry will usually crack and is difficult to
repair in a satisfactory manner. Because of its ability to bridge cracks, synthetic
exterior finish is a good top coating for traditional three coat plaster stucco.
•
If synthetic insulated exterior finish systems are to be used, they should always
be installed with a moisture drainage system and water repellent barrier. Impact
resistant systems should be installed at lower levels adjacent to pedestrian and
service areas.
IV - 54
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FACILITIES - THE BRANCHES
BUILDING SHELL TECHNICAL GUIDELINES
If aluminum storefront or curtain wall systems are to be used, careful attention
should be paid to the system design and installation. Most systems use dry
glazing and depend upon gravity draining of water to the outside. Thermal break
systems are now available and should be considered in an effort to reduce
interior winter sweating maintenance problems and to increase thermal
insulation.
Thermal Insulation
•
Walls and ceiling should be insulated with mineral fiber insulation encased in
fire-rated protective plastic or paper sleeves to reduce the amount of fibers in the
air.
•
Care must be taken when using sprayed-in-place plastic foam or cellulose
materials such as insulation. Although generally good insulators, these materials
limit access to ceilings or walls when future work in those areas needs to be done.
•
When the building design requires roof insulation under the roof membrane, the
insulation must be dense enough to support the roofing installation work and
should be a closed-cell, non-gassing insulation compatible with the roofing
membrane.
Water penetration and Vapor Control
•
Wall penetrations such as doors and windows should be protected from water
damage with metal flashing such as copper, lead coated copper, stainless steel,
tern coated stainless steel or metal laminates. Avoid the use of thermoplastics or
bituminous sheet membranes which may to break down chemically when
subjected to other building materials. Also avoid the use of factory painted sheet
metal which cannot be soldered.
•
Use elastomeric sealants such as urethane or silicone with backer rods at
expansion and control joints. Sealants must be compatible with substrate. Use
latex, acrylic and siliconized caulks at interior conditions only.
•
Window, door penetrations, and other penetrations through the exterior building
envelope should be sealed with expanding foam to reduce air infiltration.
•
To protect flooring materials, floor slabs constructed directly on the ground must
be protected from ground water vapor transmission. This is usually accomplished
with an under slab vapor barrier. If the site water table is particularly high, a
quality waterproof membrane must be installed.
FACILITIES - THE BRANCHES
BUILDING SHELL TECHNICAL GUIDELINES
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Durability
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IV - 55
To protect the building insulation from being saturated with moisture, provide a
vapor retarder membrane at the stud face behind gypsum board at exterior walls.
Building wrap over exterior sheathing at exterior stud wall construction should
be considered to control air infiltration.
Buildings with a masonry back-up wall should have a water based liquid vapor
retarder applied to prevent water damage to interior surfaces.
The ability of a building to withstand the cycles of nature and human use is
normally associated with the quality of the materials and craftsmanship used in
construction.
New projects should be carefully reviewed before requesting bids to ensure that
only those products and procedures with a good durability record are used in the
project.
Appearance and Compatibility With Surroundings
•
Effort should be made to assure the design of a building which relates visually
and aesthetically to its physical location and environment. The choice of design
features and appearance is often dictated by programmatic requirements, but the
approval of local residents, who will ultimately be the end users, should be
incorporated into the design process.
•
Local cultural character can often be used to determine the materials and
appearance of a building, but should not be the sole criteria for visual design. The
local neighborhood should receive a building that represents the over-all goals
and quality established by the central library system.
Environmental Conservation
•
The City of Dallas policy is to adhere to the principles of sustainable architecture.
The goal is to develop buildings that are sensitively designed to the
environmental factors of the site, the use of renewable materials and minimal
impact to energy consumption in the production of materials and in the building
systems operations. The L.E.E.D.S. program is currently being used on public
buildings. Other programs may evolve over time as national standards are
adopted.
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FACILITIES - THE BRANCHES
BUILDING STRUCTURAL ENGINEERING GUIDELINES
BUILDING STRUCTURAL ENGINEERING GUIDELINES
Codes and Regulations
All new library facilities shall have its structural components designed by a Registered Professional
Engineer in the State of Texas, and all structural drawings shall have his sealed affixed. The structural engineering design shall comply with the latest edition of the following codes:
A.
City of Dallas Building Code
B.
American Concrete Institute
C.
American Institute of Steel Construction
D.
Steel Joist Institute
In the event of discrepancies between these codes on a specific item, the most conservative
approach shall be followed.
Design Live Loads
Design Live Loads shall be as indicated by the appropriate building code section, except that the
following minimum live loads shall be used in the structural design of floors:
a)
Public Areas
100 psf (150 recommended for flexibility)
b)
Stack Rooms
150 psf
c)
Mechanical Rooms
125 psf
The Architect and the Structural Engineer shall determine if it is intended to have high density filing or shelving systems in the library immediately upon occupancy or at some future date after the
building is completed. Floors shall be designed to safely support the loads imposed by those systems, and the areas designated for those special loads shall be clearly indicated in the floor framing plan.
The structural drawings shall include appropriate notes listing the design live loads for which the
structure is designed.
Floors shall be designed sufficiently rigid to prevent objectionable vibrations.
Foundations
FACILITIES - THE BRANCHES
BUILDING STRUCTURAL ENGINEERING GUIDELINES
IV - 57
Building foundations shall be designed following strictly the recommendations given in the
Geotechnical Investigation Report. However, shallow foundation systems shall be avoided, except
in cases where shale or limestone rock formations are found very close to the proposed finished
floor elevation. In general use either straight shaft or underreamed belled drilled piers, with a minimum length of 8 feet regardless of the depth from top of drilled pier to the bearing formation.
Spread footings on sand may be used if recommended by the geotechnical engineer but not on clay.
Provide trapezoidal carton void forms as recommended by the Geotechnical Investigation Report,
to prevent expansion of clay soils from exerting pressure on the bottom of grade beams. The bottom of perimeter grade beams must be set 12 inches minimum below final outside grade.
If the ground floor is designed as a suspended structural slab, provide an accessible crawl space (18
inches clear below lowest member) with 2-inch thick, 2500 psi unreinforced mud slab properly
sloped and drained. All crawl spaces must be ventilated and lighted. Typically the finish elevation
level of the slab should be a minimum of 6” above the exterior finish grade level.
Slab-on-Grade Ground Floors
Slab-on-grade ground floors shall be designed only if the existing surficial site soils are inactive
(Plasticity Index less than 15) or if the slab-on-grade subgrade may be improved to reduce the
Potential Vertical Rise (PVR) to 1 inch or less in accordance with the recommendations of the geotechnical engineer, and that approach is agreeable to the City. During the Schematic Design Phase
the Architect and Structural Engineer will submit to the City the proposed method for designing the
ground floor.
Provide slab on-grade control joints (construction or contraction joints) as required to break the slab
into sections with a maximum area of approximately 400 square feet. Provide "diamond" leaveouts
at all columns, with control joints intersecting the corners of the leaveouts. The top of exterior and
interior grade beams, as well as the top of interior drilled piers, shall be set not less than 8 inches
below the top of the slab-on-grade. Slab-on-grade shall not be cast monolithically with grade
beams. All grade beams shall be formed on both sides. Earth forming shall not be permitted. Design
slab reinforcing using re-bars supported by chairs. Do not use welded wire fabric reinforcing. Do
not use postensioning steel tendons. Provide not less than 3 inches of clear cover over electrical or
mechanical conduits embedded in the slab. Provide minimum 8-mil polyethylene vapor barrier
sheets between subgrade and slab-on-grade. Use minimum f 'c = 3,000 psi concrete, with a maximum 1-inch aggregate size, and a maximum slump of 5 inches.
IV - 58
FACILITIES - THE BRANCHES
BUILDING STRUCTURAL ENGINEERING GUIDELINES
Structurally Supported Ground Floors
Ground floors designed as structurally supported slabs may consist of suspended structural systems
(usually steel or concrete) with a crawl space, or concrete slabs and beams cast over carton void
forms or loose inert fill, without a crawl space. Depending on cost and other factors, the use of a
suspended structural system with a crawl space is favored over any other alternatives.
Suspended structural systems made out of precast or cast-in-place concrete are preferred over structural steel. However, if a suspended structural steel system with a crawl space is selected, use steel
wideflange beams (either composite or non-composite) and concrete topping over form metal deck,
with a minimum slab thickness of 5". A maximum span length to beam depth ratio of 20 shall be
used when designing floor beams made out of structural steel. Do not use steel joists. Specify a
good corrosion protection shop priming system, with a minimum dry film thickness of 5 mils.
If a precast concrete system is utilized for the ground floor use a minimum concrete topping thickness of 2 inches at midspan of precast members. Provide control joints using "T-strips" set in the
fresh concrete topping in line with the joints between members. Provide welded wire reinforcing of
adequate size in the concrete topping to control cracking.
If a cast-in-place concrete system is used, special attention shall be given to construction joint locations and details. The structural framing plans, sections and notes shall clearly indicate the location
of permissible construction joints, to be located within the middle third of the spans. Provide sections and details as required to define the size and arrangement of reinforcing steel dowels. Provide
details as required showing additional reinforcing steel at corners and openings. Provide beam
schedules and typical bar bending diagrams as required. Specify the compressive strength, maximum water-cement ratio, minimum cement content, maximum coarse aggregate size and slump to
be used in the design of the concrete mixes for the different parts of the structure, in accordance
with the recommendations of the American Concrete Institute. Use minimum f 'c = 4,000 psi for
suspended floor systems.
If a structurally supported slab on carton forms is used, provide minimum 8-mil polyethylene vapor
barrier sheets between the carton forms and the concrete slab. Develop clear notes and specifications to ensure that carton forms that are defective or have been weakened by long periods of exposure to rain are removed from the site and replaced prior to placing the concrete. Specify that all
reinforcing steel is to be supported by chairs and tied as required before placing the concrete. Do
not allow the beams to be cast monolithically with the slab. Provide specifications and notes as
required to indicate that the slab is to be cast at least 7 days after the beams have been poured. Show
construction joint details indicating how the slab is to be doweled to the beams.
FACILITIES - THE BRANCHES
BUILDING MECHANICAL ENGINEERING GUIDELINES
IV - 59
The following systems material & performance requirement should be evaluated in the design
of building systems.
Heating System
Boilers
Capacity
Efficiency
Durability Features: I.E., Liners, Materials & Construction
Maintenance access hatches and doors
Radiators
Efficiency and Capacity per foot
Durability of materials and construction
Accessibility for maintenance
Ductwork
Construction-Galvanized Steel w/Fiberglass insulation, Flex duct at air devices only, NO
"FUZZ DUCT"
Design- Flexibility to accommodate future changes, i.e.,, VAV versus constant volume
Piping
Copper Pipe with Jacketed insulation, isolation as required.
Fans
Sized to deliver volumes and pressures QUIETLY
Require Manufacturers Warranty
Maintainability: i.e., Access doors, Belt Drives, Self-lubricating bearings, or lubricating
cups
Controls
Adequate number of thermostat, i.e. one per 1200 Square Ft.
Solid State for durability and flexibility
Hot Water Pumps
Sized for System pressure and volume
Designed for system static pressure and Temperature
Cooling System
Rooftop A/C Unit
Sized for CFM's and BTU's required
Designed for Outdoor Operation
Access doors and panels
Chilled Water preferred. DX systems should be avoided
Permanently lubricated bearings or lubrication cups for bearings
IV - 60
FACILITIES - THE BRANCHES
PLUMBING GUIDELINES
Air Handler (Buildings)
Sized for CFM's and BTU's required
Access doors and panels
Chilled Water preferred over DX ( Durability & Energy Efficiency)
Permanently lubricated bearings or lubrication cups for bearings
Air Handlers (Auditorium)
Sized for CFM's and BTU's required
Access doors and panels
Chilled water preferred over DX (Durability)
Permanently lubricated bearings or lubrication cups for bearings
Chillers
Sized for GPM's and BTU's required
For Air-Cooled Units Sized at 105F Ambient
Non-CFC refrigerants
Cooling Towers
Sized for GPM's and BTU's required Sized at 105F dry bulb, 78Fwet.
Fiberglass Plastic construction and fill
Access doors and panels
Chilled Water Pump
Sized for GPM's and pressure drop required
Permanently lubricated bearings or lubrication cups for bearings
Designed for ease of Maintenance
PLUMBING GUIDELINES
Water Piping
Sized for fixtures plus growth
Copper or Steel, no PVC
In chases where possible, isolation bushings as needed
Sanitary Serer Piping
Sized and sloped for flow
Cast Iron Soil Pipe, no PVC
In chases where possible
Storm Drainage piping
Sized and sloped for 100 year rainfall, with overflow where needed
Steel, no PVC
FACILITIES - THE BRANCHES
PLUMBING GUIDELINES
Grates, grilles or domes on all intakes, provide roof access for cleaning
Gas Piping
Sized as needed for Maximum possible flow
Black Iron pipe with lining.
Roof mounted where possible, attic runs where not, with access
Valves, Traps and accessories
Sized as needed
Copper or brass
Nut assembly for easy disassembly
Plumbing Fixtures
Water conserving fixtures w/infrared beam automatic operation
Porcelain fixtures with copper water pipe.
Individual stops on each fixture
Drinking Fountains
Sized for adequate recovery rates
Designed for durability
Maintenance access
Sprinkler (Irrigation) Systems
Designed for complete coverage of area
Steel pipe and metal heads
Easily adjustable time clock controls
IV - 61
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FACILITIES - THE BRANCHES
TYPICAL BRANCH PROGRAMMING ANALYSIS
TYPICAL BRANCH PROGRAMMING ANALYSIS
An important goal of the Master Plan is to promote greater consistency in the design, quality and
functionality of all branch facilities. This is not meant to be overly prescriptive in a way that would
limit or stifle the creativity and variety of design needed to respond to each site and every neighborhood’s needs. There will always be some variation in the size and distribution of program elements due to the special needs of the communities, but there are basic minimum space requirements
and plan relationships that must be met to assure a successful design.
In order to develop the proposed new library ‘Kit of Parts’ recommendations that follow later in this
section, it was important for the library planners to fully analyze the existing programs of the
branches. The following quantitative look at an existing library program is provided to illustrate
what, in the opinions of both the library staff and the consultants, comes closest to being an “ideal”
program: