ASTM C981-95
(Guide)Standard Guide for Design of Built-Up Bituminous Membrane Waterproofing Systems for Building Decks
Standard Guide for Design of Built-Up Bituminous Membrane Waterproofing Systems for Building Decks
SCOPE
1.1 This guide describes the design of fully adhered built-up bituminous membrane waterproofing systems for plaza deck and promenade construction over occupied spaces of buildings where covered by a separate wearing course.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 981 – 95
Standard Guide for
Design of Built-Up Bituminous Membrane Waterproofing
Systems for Building Decks
This standard is issued under the fixed designation C 981; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1327 Specification for Bitumen-Saturated Woven Burlap
Fabrics Used in Roofing and Waterproofing
1.1 This guide describes the design and installation of
D 1668 Specification for Glass Fabrics (Woven and
bituminous membrane waterproofing systems for plaza deck
Treated) for Roofing and Waterproofing
and promenade construction over occupied spaces of buildings
D 2178 Specification for Asphalt Glass Felt Used in Roof-
where covered by a separate wearing course.
ing and Waterproofing
1.2 This standard does not purport to address all of the
D 2626 Specification for Asphalt-Saturated and Coated Or-
safety concerns, if any, associated with its use. It is the
ganic Felt Base Sheet Used in Roofing
responsibility of the user of this standard to establish appro-
D 2822 Specification for Asphalt Roof Cement
priate safety and health practices and determine the applica-
D 4022 Specification for Coal Tar Roof Cement, Asbestos
bility of regulatory limitations prior to use.
Containing
2. Referenced Documents D 4586 Specification for Asphalt Roof Cement, Asbestos
Free
2.1 ASTM Standards:
D 4601 Specification for Asphalt-Coated Glass Fiber Base
C 33 Specification for Concrete Aggregates
Sheet Used in Roofing
C 136 Test Method for Sieve Analysis of Fine and Coarse
D 4990 Specification for Coal Tar Glass Felt Used in
Aggregates
Roofing and Waterproofing
C 208 Specification for Cellulosic Fiber Insulating Board
D 5295 Guide for Preparation of Concrete Surfaces for
C 717 Terminology of Building Seals and Sealants
Adhered (Bonded) Membrane Waterproofing Systems
C 755 Practice for Selection of Vapor Barriers for Thermal
Insulation
3. Terminology
D 41 Specification for Asphalt Primer Used in Roofing,
3.1 Definitions—The definitions of the following terms used
Dampproofing, and Waterproofing
in this guide are found in Terminology C 717: creep; cold joint;
D 43 Specification for Coal Tar Primer Used in Roofing,
compatibility; construction joint; hydrostatic pressure;
Dampproofing, and Waterproofing
laitance; reglet; spalling; waterproofing.
D 173 Specification for Bitumen-Saturated Cotton Fabrics
3.2 Definitions of Terms Specific to This Standard:
Used in Roofing and Waterproofing
3.2.1 cellular (adj).—having a composition of plastic or
D 226 Specification for Asphalt-Saturated Organic Felt
5 rubber with relative density decreased by the presence of cells
Used in Roofing and Waterproofing
disposed throughout its mass. In closed-cell materials, the cells
D 227 Specification for Coal-Tar Saturated Organic Felt
5 are predominantly separate from each other. In open-cell
Used in Roofing and Waterproofing
materials, the cells are predominantly interconnected.
D 312 Specification for Asphalt Used in Roofing
3.2.2 construction joint—a butt joint formed in a structural
D 449 Specification for Asphalt Used in Dampproofing and
slab in order to end one pour and start another pour later. The
Waterproofing
joint is usually a cold joint and may be held together with
D 450 Specification for Coal-Tar Pitch Used in Roofing,
reinforcing steel in the slab, or the steel may be discontinuous
Dampproofing, and Waterproofing
by design.
3.2.3 curing time—the period between application and the
This guide is under the jurisdiction of ASTM Committee C-24 on Building
time when the material reaches its design physical properties.
Seals and Sealants and is the direct responsibility of Subcommittee C24.80 on
3.2.4 deck—the horizontal structural substrate supporting
Building Deck Waterproofing Systems.
Current edition approved Dec. 10, 1995. Published February 1996. Originally the plaza deck system. See also structural slab.
published as C 981 – 83. Last previous edition C 981 – 89.
3.2.5 deflection—the deviation of a structural element from
Annual Book of ASTM Standards, Vol 04.02.
its original shape or plane due to physical loading, temperature
Annual Book of ASTM Standards, Vol 04.06.
changes, or rotation of its supports.
Annual Book of ASTM Standards, Vol 04.07.
Annual Book of ASTM Standards, Vol 04.04.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 981
3.2.6 drainage course—See percolation layer, geotextile 3.2.18 protection board—a semi-rigid sheet material placed
drainage composite, and Fig. 1. on top of waterproofing membrane to protect it against damage
3.2.7 dry occupancy—an occupied space below the plaza during subsequent construction and to provide a protective
deck system in which the computed or anticipated relative barrier against compressive and shearing forces induced by
humidity is below 30%. materials placed above it (see Fig. 1).
3.2.8 dynamic—exhibiting change or movement. 3.2.19 raggle—same as reglet.
3.2.9 finish—the exposed top surface of the plaza deck 3.2.20 scaling—same as spalling.
system, or traffic, or wearing surface. 3.2.21 static—exhibiting little or no change or movement.
3.2.10 flashing—(1) a generic term describing the transi- 3.2.22 structural slab—a horizontal, supporting, cast-in-
tional area between the waterproofing membrane and surfaces place, concrete building deck (see Fig. 1).
above the wearing surface of the plaza. (2) a terminal closure
4. Significance and Use
to prevent ingress of water into the system.
4.1 This guide provides information and guidelines for the
3.2.11 floated finish—a concrete finish provided by consoli-
selection of components and the design of a built-up bitumi-
dating and leveling the concrete with only a power driver or
nous membrane waterproofing system in building deck con-
hand float, or both. A floated finish is coarser than a troweled
struction. Where the state of the art is such that criteria for
finish. For specifications, see ACI-301-72 (1975).
particular conditions are not established or have numerous
3.2.12 freeze-thaw cycle—the freezing and subsequent
variables that require consideration, applicable portions of
thawing of a material.
Design Considerations, Sections 5-17, serve as reference and
3.2.13 geotextile drainage composite—a performed porous
guidance for selection by the designer of the system.
material, usually plastic, with a filter-type fabric over it.
3.2.14 grout—concrete containing no coarse aggregates; a
DESIGN CONSIDERATIONS
thin mortar.
3.2.15 insulating concrete—a lightweight concrete made 5. General
with lightweight coarse aggregate and having relatively low
5.1 The design of plaza deck waterproofing cannot be
insulating characteristics.
satisfactorily determined without consideration of the several
3.2.16 percolation layer (drainage course)—a layer of
subsystems, their material components, and interrelationships.
washed gravel that allows water to filter through to the drain
The proper selection from a variety of components that form a
(see Fig. 1).
built-up bituminous membrane waterproofing system must be
3.2.17 ply—a single layer of membrane reinforcement in
predicated upon specific project requirements and the interre-
the bituminous membrane waterproofing system.
lationship of components. The variety of the types of surfaces
exposed to weather, the difference of climatic conditions to
which the deck is exposed, and the interior environmental
requirements of the occupied space are major determinants in
the process of component selection. Essential to determination
of the deck design components is information relative to
temperature extremes of the inner and outer surfaces, precipi-
tation rates, solar exposure, prevailing wind direction, the
pattern and reflectivity of adjacent structures, anticipated
amount and intensity of vibration resulting from function or
adjacent occupancies, and design live loads both normal and
emergency.
6. Compatibility
6.1 It is essential that all components and contiguous
elements be compatible and coordinated to form a totally
integrated waterproofing system.
7. Major Components and Subsystems
7.1 The plaza deck system is normally composed of several
subsystems: the structural building deck (membrane substrate),
the waterproofing membrane, the drainage subsystem, the
thermal insulation, protection or working slab, and the wearing
course (see Fig. 1). Fig. 1 as well as details, subsystems,
components, and illustrations that follow are intended to
illustrate a principle but are not necessarily the only solution
for a diversity of environments.
FIG. 1 Basic Components of Built-up Bituminous Membrane Wa-
8. Horizontal or Deck Substrate
terproofing System with Separate Wearing Course (see Section
7) 8.1 The building deck or substrate referred to in this guide
C 981
is reinforced cast-in-place structural concrete. (2 in.) and should be sealed or weighted (see Practice C 755).
8.1.1 High early strength and insulating concretes do not
8.5.3 Chemical Curing—Liquid or chemical curing com-
provide suitable substrates. Additives made to the concrete mix
pounds applied to the surface of the structural slab should not
(such as calcium chloride) to promote curing, reduce water
be used unless approved by the manufacturer of the built-up
requirements, or modify application temperature requirements
bituminous membrane as the material may interfere with the
should not be used unless the manufacturer of the waterproof-
bond of the membrane to the structural slab.
ing system specifically agrees.
8.6 Dryness—Membrane manufacturer’s requirements for
8.1.2 Precast concrete slabs pose more technical problems
substrate dryness vary from being visibly dry to having a
than cast-in-place concrete, and the probability of lasting
specific maximum moisture content. Since there is a lack of
watertightness is greatly diminished and difficult to achieve
unanimity in this regard, it is necessary to conform to the
because of the multitude of joints that have the capability of
manufacturer’s requirements for the particular membrane be-
movement and must be treated accordingly. Moving joints are
ing applied. Adequate drying of residual moisture from slabs
critical features of waterproofing systems and are more critical
poured over a permanent metal deck will normally take longer
when sealed at the membrane level than at a higher level with
than from slabs stripped of forming. Subsequent underside
the use of integral concrete curbs. Such curbs are impractical
painting of stripped concrete slabs that might inhibit moisture
with precast concrete slabs and necessitate an even more
vapor transmission and possibly cause loss of membrane
impractical drain in each slab. Other disadvantages of precast
adhesion should be avoided.
concrete slabs are their inflexibility in achieving contoured
8.7 Joints—Joints in a structural concrete slab are herein
slope to drains and the difficulty of coordinating the placement
referred to as reinforced joints, unreinforced joints, and expan-
of such drains.
sion joints.
8.2 Slope for Drainage—Drainage at the membrane level is
8.7.1 Reinforced Joints—Reinforced joints consist of hair-
important. When the waterproofing membrane is placed di-
line cracks, cold joints, construction joints, and isolation joints
rectly on the concrete slab, a monolithic concrete substrate
1 held together with reinforcing steel bars or wire fabric. These
slope of a minimum 11 mm/m ( ⁄8 in./ft) should be maintained.
are considered static joints with little or no movement antici-
The maximum slope is related to the type of membrane used.
pated because the slab reinforcement is continuous across the
Slope is best achieved with a monolithic pour as compared
joint.
with a separate concrete fill. The fill presents the potential of
8.7.2 Nonreinforced Joints—Nonreinforced joints consist of
additional cracks and provides a cleavage plane between the fill
and structural slab. This cleavage plane complicates the detec- butt-type construction joints and isolation joints not held
together with reinforcing steel bars or wire fabric. These joints
tion of leakage in the event that water should penetrate the
membrane at a crack in the fill and travel along the separation are generally considered by the designer of the structural
system as nonmoving or static joints. However, the joints
until reaching a crack in the structural slab.
should be considered as capable of having some movement, the
8.3 Strength—The strength of concrete is a factor to be
magnitude of which is difficult to predict.
considered with respect to the built-up bituminous membrane
insofar as it relates to finish, bond strength, and continuing
8.7.3 Expansion and Seismic Joints—Expansion joints, as
integrity. The cast-in-place structural concrete should have a
differentiated from control joints, are designed to accommo-
3 3
minimum density of 1762 kg/m (110 lb/ft ).
date movement in more than one direction, are an integral part
8.4 Finish—The structural slab should have a finish of of the building structural system, and must be carried through
sufficiently rough texture to provide a mechanical bond for the the entire structure. Expansion joints are incorporated in the
membrane but not so rough to preclude achieving continuity of structural frame (1) to reduce internal stresses caused by wide
the membrane across the surface. As a minimum, ACI 301-72 temperature ranges or differential movement, or both, between
(1975) floated finish is required with ACI 301-72 (1975) structural elements as might be the case in large adjoining
troweled finish preferred, deleting the final troweling.
heated and unheated spaces; (2) where there are different
foundation settlement conditions between adjacent elements;
8.5 Curing—Curing the structural slab is necessary to
or (3) where movements between high- and low-attached
provide a sound concrete surface and to obtain the quality of
structures are anticipated. Seismic joints are a special case in
concrete required. Curing is accomplished chemically with
moisture and should not be construed as drying. which the joints are generally quite large and are designed to
limit damage to the structural frame during earthquakes.
8.5.1 Moist Curing—Moist curing is achieved by keeping
Expansion and seismic joints are best located at high points of
the surfaces continuously wet by covering with burlap satu-
contoured substrates to deflect water away from the joint. For
rated with water and kept wet by spraying or hosing. The
expansion joints
...
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