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DRAINAGE AND VENTILATION SYSTEM FOR
BUILDING WALL ASSEMBLIES
TECHNICAL FIELD
The embodiment relates to several common types of building wall assembly
systems used
in commercial and residential buildings. Specifically, the embodiment may be
used in masonry
cavity walls, cement plaster finish systems (stucco) and Exterior Insulation
Finish Systems
(EIFS). Stucco and EIF=S are referred to in this disclosure as typical
"veneer" wall assemblies.
A cavity wall genE~rally ha:o a structurally significant inner "wythe" made of
concrete block
or other framing materiials, and an exterior wythe, which is typically non-
load bearing, made of
brick, stone, or other masonry material. Between the wythes is a cavity which
provides an air
space which must be kept open for the lifetime of the building to allow any
accumulation of
water to drain and air to circulate. The embodiment prevents mortar and debris
from entering
the cavity, bridging the ties, obstructing the air space and blocking the
drainage weeps. In
addition, a new ventilation system for head joint vents and wall cap vents is
described. Pressure
equalization within the cavity i:> assured by application of this embodiment.
The likelihood of
premature failure of the cavity wall is greatly reduced by using the
construction system
disclosed herein which prevent:. the air space and weeps from becoming
obstructed during or
after building construction.
Stucco walls generally have a structurally significant masonry wall or a
sheathed framing
system that supports metal lathe embedded in wet stucco. Stucco is cement
plaster applied to
the outside of a wall, u;>ually in several layers, to create a weather-
resistant finished surface or
exterior layer. The sheathing is typically covered with a protective air
infiltration barrier such as
building felt or other material that resists water penetration but allows
water vapor to escape.
Metal lath is mechanically fastened over the air infiltration barrier to
secure the stucco to the
structure. Cracks may develop in the stucco finish due to shrinkage of the
cementitious
materials, movement of the building or other causes. Such cracks create a
potential for water
infiltration through the stucco barrier to the structural components of the
building. Water
accumulation may cause rotting of wooden materials, corrosion of metallic
components,
degradation of interior finishes, .and damage to electrical devices located in
a wall. Traditionally,
stucco has been installed in direct contact with the air infiltration barrier
and sheathing without
including specific methods for drainage and ventilation to remove accumulated
moisture.
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The embodiment provides drainage to remove water that penetrates the stucco
finish and
ventilation to dry the wall assembly. The embodiment removes water by allowing
any water that
penetrates the stucco to flow through a non-woven mat layer interposed between
the air
infiltration barrier and the stucco. Gravity moves the water through the non-
woven mat to weep
holes installed at the bottom of t:he finished wall. The weep holes allow air
to circulate through
the non-woven mat and vent 'water vapor to the atmosphere. An additional
benefit of the
present embodiment is that the resilience of the non-woven mat allows more
thorough
penetration and encapsulation .of the metal lath by the cementitious coating.
An EIFS wall system has do exterior layer made of an acrylic-modified,
Portland cement
containing material that is customarily applied directly to expanded
polystyrene board insulation
or to a cementitious structural sheathing material. EIFS is applied to the
outside of a wall in a
thin exterior layer, approximately ~/s," whereas the thickness of traditional
stucco is 5/s" to'/."
EIFS manufacturers m<ay specif'~ that the finished exterior layer is actually
made from multiple
layers of coating materials. EIF~~ typically includes a separate reinforcing
product such as glass
fiber fabric. The appearance of a~n EIFS wall is similar to traditional stucco
systems. As originally
introduced, EIFS was Considered a barrier system because it was believed that
it would reliably
prevent water penetration. ExpESrience has shown that EIFS, like stucco, can
develop cracks
that allow water to penetrate and damage the building components in all of the
same ways that
water damages stucco walls. The EIFS industry has responded to the problem of
water damage
to the system by introducing the concept of water management. This concept
recognizes that
a wall can seldom be constructed in a way that guarantees water will never
penetrate the
completed assembly. I~owever, the materials and methods used in attempts to
adequately
manage water penetration present undesirable limitations. The embodiment
provides drainage
to remove water that penetrates the EIFS and ventilation that dries the wall
assembly. The
2.5 embodiment removes vvater by allowing any water that penetrates the EIFS
to flow through a
fibrous mesh, or non-vroven m;at, interposed between the EIFS substrates and
the polymer
based coating. Water moves through the non-woven mat to weep holes installed
at the
lowermost level of the finished wall. Air circulates through the non-woven mat
and vents water
vapor to the atmosphere.
BACKGROUND AND SUMMARY
In cavity wall construction, an inner wall portion or wythe is usually made of
concrete block,
wood framing, or steel framing. lNhen frame construction is used, sheathing
materials such as
wood, gypsum board or cementitious sheet material, are installed on the outer
side of the
3.5 framing members. Board insulation is often applied to the outer side of
the concrete block or
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sheathing and ordinary interior finish materials to the interior side of the
inner wythe. A second,
exterior wythe is constructed using the desired exterior finishing material
such as brick, block,
or stone to cover the insulation or sheathing. The facing sides of the two
wythes are typically
separated two to four inches to form a cavity; the cavity provides an air
space and may include
insulation. Walls formed from finro wythes separated by an air space of less
than finro inches are
sometimes denominated "void collar joint walls." For simplicity, this
disclosure will refer to both
types as a "cavity wall."
Regardless of the material used in construction of the wythes, it is essential
that an air
space be maintained between them. It is also essential to provide a way to
remove moisture
from the cavity. Drainage holes, openings, or channels called "weeps" are
normally provided
at the first course of brick above grade elevation, at lintels and at other
flashings which direct
water away from the iniierior of the building. Moisture can enter the cavity
due to condensation,
permeation, plumbing faults, roof faults, and cracks in the masonry which
inevitably occur over
time, among other ways. It is irnpossible to prevent small amounts of water
from penetrating
brick or other masonry walls because the materials are porous and prone to
cracking. If water
accumulates in the cavity between the inner and outer masonry portions of a
wall, problems
with degradation of the brick, efflorescence, interior damage, and damage to
foundations can
develop.
A common problem in cavity wall construction is that excess mortar and other
debris may
fall into the cavity and create places where moisture can accumulate. If
mortar or other
construction debris obstructs the: weeps or provides a place where water can
pond, the build-up
of moisture can damage insulation, carpets, interior wall finishes and
furnishings. Efflorescence
is another problem resulting frorn accumulation of water in the wall. In
addition, the freezing of
accumulated moisture c;an cause spalling and other damage. Although various
techniques have
been implemented in attempts to prevent air spaces, vents and weeps from
becoming blocked,
but none has proven adequate.
One technique to (keep the cavity wall air space open is to increase its size.
However, that
necessarily results in increased foundation size, thicker walls, more
expensive window and door
installations, and greater labor costs.
Other common tE:chnique~s also have serious drawbacks. For example, the cavity
is
sometimes filled with pea gravel to prevent dropped mortar from filling the
weeps. Pea gravel
itself will sometimes block they weeps or else simply raise the elevation at
which mortar
accumulates to the hr:ight of the pea gravel. The installation of pea gravel
is laborious,
especially as the wall increases in height.
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Another technique requires construction workers to lift a board through the
cavity to
dislodge and remove dropped mortar. In the course of lifting a board through
the cavity, the
board may catch on bricks which have partially set and compromise the
integrity of the bond
of the mortar to the brick. The technique is also disruptive of the normal
work of the mason and
is difficult to accomplish when horizontal joint reinforcement materials are
incorporated into the
wall design.
Another technique is described by Ballantyne in U.S. Patent No. 4,852,320 and
requires
the mason to install inclined shapes of sheet or extruded metal within the air
space of the cavity
wall. In U.S. Patent IVo. 5,230,189, Sourlis describes shapes made of polymer
mesh for
'~ 0 catching mortar debris as it dlrops into the wall cavity. Although such
techniques may be
improvements to traditiional mel:hods, they do not overcome all of the
problems associated with
cavity waU construction. First, the on-site installation is difficult to
properly supervise because
the components are hidden from view almost immediately after installation. In
the event that
problems with the installation are discovered, correction is likely to be
expensive, perhaps
7 5 prohibitively so. Secornd, the techniques and equipment are designed to
trap and collect debris.
Once collected, that dE:bris may itself accumulate water that could lead to
structural damage.
Another shortcoming of previous attempts to solve the problem is the expense
of implementing
them. Most are relatively unproven and represent a substantial initial expense
to obtain an
uncertain benefit.
20 What is needed, vlhen, is a way to keep excess mortar and other
construction debris out
of the air space from the very beginning. The present embodiment meets that
need by
preventing, from the outset, creation of excess mortar debris which could
block the weeps and
allow moisture to accumulate, and by excluding other debris from the cavity by
preventing it
from entering in the first place. Not only does the present embodiment prevent
blockage of
25 weeps, it also prevents bridging of masonry ties with mortar. It is
expected to reduce
construction costs by allowinc,~ smaller cavity dimensions which can reduce
the cost of
foundations and window and door openings. It is especially significant that
the present
embodiment is expected to reduce the cost for mortar by reducing waste while
increasing
productivity. The present embodiment also allows the specification of smaller
air spaces thereby
30 providing space for additional wall insulation and/or smaller foundation
sizes.
The cavity-filling mesh may be formed from any non-absorbent, non-woven co-
polymer
fibers. It is believed preferable that the cavity-filling mesh be formed of
non-woven polyester
polymer fiber with 80°~o to 100% of the fibers being 200 denier and 0%
to 20% of the fibers
being other sizes. It has been found that a satisfactory mesh can include up
to about 20% fibers
35 in the range of 15 to ~45 denier. The binder used to hold the polyester
fiber mesh in place
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preferably comprises 25% to 65% of the final product by weight. It is believed
preferable to use
a flame-retardant PVC:, EVCL polymer type binder when using polyester fibers
and to have the
weight of the binder comprise approximately 50% of the product, by weight. No
limitations to
the acceptable ratio of binder to fiber have been established experimentally.
Satisfactory results
5 have been obtained wising ratios of binder to fiber in the range from 30% to
70%. The weight
of the mesh, in a 3/e" thickness, is between five and ten ounces per square
yard, and preferably
approximately eight ounces per square yard.
The choice of particular polymers for the fibers and binders is not critical
to the
embodiment and may vary dE:pending on the price and availability of
alternatives. For the
purposes of fabricating this embodiment, all polymer materials that can be
readily formed into
a suitable non-woven mesh are deemed equivalent. Acceptable mesh samples have
also been
made using nylon, polyethylene and polypropylene. High quality samples of the
mesh have
been produced using the air-laid process from recycled polyester staple, the
material currently
believed preferable. It is likely that other recycled materials, perhaps
mixed, could be used as
'I 5 well.
Mesh used to form head ,joint weeps and cap vents could be made in the same
manner
as the mesh used in i:he cavity. However, it is believed preferable to use
thinner fibers than
those comprising the fluid-conducting medium. Compared to cavity non-woven
mat, weep and
vent mesh is preferably fabrical:ed using a higher density of thinner fibers,
resulting in less void
:'0 space and a lower ratio of binder to fiber. It is anticipated that an
ultraviolet-resistant binder
would be required in the head joint weep and cap vent mesh to prevent
photochemical
degradation.
With or without insulation, the fluid-conducting medium is attached to the
first wythe (the
inner wythe) and disposed within the air space at a distance of approximately
'/e" from the inner
:!5 surface of the second wythe (the exterior wythe). The mortar expressed
from the inner side of
the bricks as they are laid will be prevented from falling because it would
become entangled in
the mesh fibers. The expressed mortar would not extend across all of the
distance from
between the second wythe and the first wythe whether it is fitted with board
insulation or other
sheathing material. Thus, an uninterrupted air space will be maintained from
the top to the
a0 bottom of the wall cavii:y and throughout the entire length of the wall to
assure proper moisture
drainage and air circulation.
Included in the present embodiment is the optional provision of ventilation
mesh for use
in vented masonry cavity wall systems. Mesh panels cut to the size of the end
section of the
masonry unit being usE~d to construct the exterior wythe may be installed in
place of mortar in
.c5 some of the "head" (vertical) ;joints near the bottom of a wall. The mesh,
when made with
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ultraviolet resistant binder and fiber, is believed to be superior to
previously known drainage
devices. The non-woven polymer mesh will exclude insects and other vermin from
the air space
more effectively than the currently known drainage inserts.
In addition, the non-woven polymer mesh may be fabricated in colors and
textures that
resemble the appearance of mortar. It is possible for designers to specify
adequate drainage
and ventilation without compromising the aesthetic appeal of the exterior
facade.
The mesh, or heavier formulations of the mesh, can not only be used between
the brick
head joints, but may odso be used at the top of the wall beneath the capstone
or wood blocking
and flashing to provide an opening for air ventilation and circulation.
Ventilating the cavity
between the wythes can reduce the formation of frost and mildew by allowing
any moisture that
enters the cavity, whether as liquid or vapor, to escape rather than
accumulate
Another advantage of the presently disclosed system is that it provides
improved insulation
performance. Mortar bridging an air space allows thermal transfer between the
wythes across
the air space. The e~mbodim~ent prevents this thermal transfer by preventing
mortar from
3 5 entering the air space.. In addition, when mortar bridging is present,
water may accumulate and
degrade the insulation. The non-woven mat is expected to provide enhanced
thermal properties
compared to an air space alone.
A further advantage of the present embodiment is that mortar is prevented from
accumulating on the adjustable masonry ties which are designed to accommodate
normal
movement of the wythes. Differential movement caused by thermal expansion and
contraction
of the building materials can result in cracking if mortar obstructs the air
space or bridges the
masonry ties. This embodiment allows adjustable ties to function as intended
rather than as
limited by the accumulation of mortar. In addition, the structure may be less
susceptible to
damage due to seismic activity.
It is to be understood that, although the fluid-conducting medium is
preferably bonded to
insulation sheet material in the facility where the product is manufactured,
it may also be
pressed into place at the construction site or affixed using any suitable
adhesive. It is
anticipated that sheets of fibrous mesh fluid-conducting medium could be
installed by placing
them between the ma:;onry ties. It is further to be understood that the
preferred resilience and
strength of the material will be 'sufficient to allow it to hold mortar but
also soft enough to permit
workers to readily insi:all masonry ties and to otherwise work with it easily.
A further advantage of the embodiment disclosed herein is that it provides a
method for
equalizing air pressure throughout the cavity wall when used in conjunction
with open, or
vented, head joints in lieu of rope wicks. When wind is blowing, the pressure
on the down-wind
side of the building is less than the pressure on the up-wind side. If the
outside of the building
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is wet, for example dine to rain, the existence of any significant pressure
differential will cause
water to be drawn from the outside of the building through even very small
cracks, defects, and
other openings in the masonry. In addition to climatic causes, a pressure
differential exists
between the interior and the exterior of most buildings due to the operation
of mechanical air
handling systems that exhaust "old" air and introduce fresh air resulting in a
net negative interior
pressure. The presence of obstructions in the air space or weeps can result in
wet spots during
rains which can be very difficult to correct. The present embodiment, by
preventing any
obstruction of the cavity air space vents or the weeps, allows air pressure to
equalize at all
points on both sides of the outer wythe and thereby reduces the extent of
water infiltration.
'I 0 The embodiment is expected to improve the overall quality of the
constructed building. The
expected improvements include reduced re-work, fewer complaints by owners, and
longer
building life. In order to obtain generally satisfactory cavity wall
construction, the industry
standard recommendation is that masonry cavity walls be configured with an air
space of from
1" to 2" in addition to any insulation (normally 4" total, including
insulation). The present
embodiment provides the benefit sought by the industry using a wall cavity
that is only 2"
(nominal). The cost of the materials used in the embodiment are offset by
savings resulting from
reduced mortar waste, reduced foundation size, lower costs to construct window
and door
openings, reduced costs for si:eel members such as lintels, cap blocking and
flashings, and
improved productivity. Unlike those approaches intended to collect
construction debris which
0 enters the cavity air space, the present embodiment may lower overall
construction costs; that
benefit is complemented by easier installation and improved quality of the
final product.
The figures of the present disclosure that depict masonry cavity walls show a
typical
installation with brick e:Kterior finish, a clearance space of'/", a mesh
thickness of'/Z" to 5/B', an
insulation layer of 1'/Z" to 2", and an interior structural masonry wall of
concrete block. The
~:5 system of the present disclosure provides the benefits normally associated
with a wall having
a nominal 4" cavity in a~ wall having a nominal 2" cavity. It is well
understood that construction
costs for a wall with a 2" cavity are much lower than the costs for a wall
having a nominal 4"
cavity. It is believed that the mat thicknesses most commonly used will be in
the range of 3/B"
to 2". Some applications may require other mat thicknesses.
3.0 Alternatives to masonry finished wall systems include veneer wall
assemblies that are
finished with cementitious materials such as stucco and EIFS. Conventional
stucco and EIFS
walls, like masonry cavity walls, can be damaged by water penetration when the
installation
does not provide specil5c, effective provision for removing water and venting
water vapor to the
atmosphere.
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In stucco construction, an inner structural wall assembly, or wythe, is
usually made of
concrete block, wood framing, or steel framing. When frame construction is
used, sheathing
materials such as wood, gypsum board or cementitious sheet material are
installed on the outer
side of the framing members. Eloard insulation may be secured to the outer
side of the concrete
block with steel framing. A stuc~~o exterior layer, analogous to the outer
wythe of masonry cavity
wall construction,, is applied to metal lath that has been affixed to the
structural wall assembly.
Stucco finishes are typically applied in several layers to achieve a thickness
of approximately
3~".
4
In EIFS construction, as with stucco construction, an inner structural wall
assembly, or
'10 wythe, is usually made of concrete block, wood framing, or steel framing.
When frame
construction is used, exterior sheathing materials such as wood, gypsum board
or cementitious
sheet material are installed on i:he outer side of the framing members. Board
insulation may be
secured to the outer side of concrete block with special-purpose, often
proprietary, fasteners.
Similarly, board insulation may be secured to wood framing or steel framing
over the exterior
'I 5 sheathing materials. P,n EIFS exterior Payer, comprised of finish coating
materials, is somewhat
analogous to the outer wythe of masonry cavity wall construction. However, the
EIFS finish
coating materials have typically been applied in a thickness of approximately
~/s' directly to the
board insulation or exterior sheathing. Wall system failures due to water
penetration and
accumulation have been caused by the absence of a cavity and air space in
traditional EIFS
a!0 assemblies
Regardless of the material used to make the exterior layer, it is essential
that an air space
or cavity be maintained between the exterior layer and the structural wall
assembly. It is also
essential to provide a way to remove moisture from the air space or cavity.
Drainage weeps
must be provided at the lowermost level of the exterior layer, at lintels and
at other flashings to
~!5 direct water away frorn the interior of the building. Moisture can
penetrate the exterior layer
through shrinkage cracks, window and door openings, inadequate flashings,
improperly applied
or failed sealants and other gaps. In addition, moisture can accumulate
between the exterior
finish coating and the structural wall assembly, among other ways, as the
result of
condensation, permeation, pluimbing faults, roof faults, vapor barrier
failures, and cracks that
..0 inevitably occur over time. Wood rot, framing degradation, metal
corrosion, sheathing
disintegration, and interior finish deterioration are some of the problems
that occur when water
accumulates between the exterior finish coating and the structural wall
assembly.
One important characteristic of the coatings used in constructing these veneer
wall
assemblies is that they have low permeability. Although the coatings were
intended to create
~~5 an impenetrable barrier to moisture, that barrier could seldom be
perfectly maintained. Moisture
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that penetrated to the interior structural wall escaped slowly in the absence
of a drainage and
ventilation system. For this reason, even small defects in the barrier coating
of a veneer wall
assembly led to significant moisture accumulation over time. The damage caused
by
accumulated water has forced the manufacturers of the materials used in this
type of
construction to adopt the concept of water management for these finish
systems. Since
traditional methods of veneer wail construction had no provision to remove
this accumulated
moisture it has recently becomes necessary to create components intended to
drain water from
these wall assemblies.
One limitation of as recenthy introduced veneer wall drainage product is that
the drainage
material can be installed only on the interior side of the thermal board
insulation. The effect of
providing drainage at the interior side of the board insulation is that the
ventilation provided by
the drainage material introduces outdoor air to the temperature-controlled
side of the thermal
envelope. In climates where year-round cooling may be required, warm moist air
that enters
through a drainage component will tend to condense. This condensation will
contribute to
potential moisture damage. In addition, when water vapor condenses, heat is
released creating
additional Toad on the cooling aystem. In climates having greater heating
requirements, the
drainage material provides a channel for cold air to enter the thermal
envelope. There is a
danger that this solution may replace one problem with another.
Veneer wall assemblies, even with the constraints identified above, remain
desirakile for
several reasons. Design opportunities are greater than those afforded by many
other
techniques. Lightweight materials used in veneer wall assemblies reduce labor
and
transportation costs. Material costs, especially for EIFS wall assemblies, are
lower than those
for comparable exterior systems. The expansive selections of colors and
textures that are
available at reasonable cost aucament aesthetic possibilities. These and other
benefits can be
realized by overcoming the known limitations of veneer wall assemblies.
These potential benefits are widely known in the construction industry. These
benefits,
unfortunately, cannot be realized in the absence of effective solutions to the
acknowledged
problems. Persons skilled in this art have long recognized the need to
overcome the
disadvantages of the techniques and products presently available. This
disclosure presents, for
the first time, an effective solution to the existing problems of veneer wall
assemblies. Not only
is the present embodirnent versatile, moderately priced, and easily installed,
it also provides
benefits not possible uaing traditional methods and materials.
The present embodiment comprises a non-woven mat fitted to the exterior side
of board
insulation and secured to the structural wall with mechanical fasteners. The
exterior layer is
applied to the outside of the non-woven mat that makes up the fluid-conducting
medium. The
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non-woven mat may also be installed at the interior side of the board
insulation. Reinforcing
fabric or metal lath may be iinstalled on the outer side of the non-woven mat
and board
insulation combination and held in position with fastener plates and
conventional mechanical
fasteners. A fastener plate specifically adapted for use with this non-woven
mat is disclosed,
5 although other fastener plates might adequately secure the non-woven mat in
place. It is also
possible that EIFS coating materials could be applied directly to the non-
woven mat.
Embodiments having the non-woven mat affixed to the board insulation prior to
delivery
to the construction site may prove to be efficient and convenient. It is
anticipated that the non-
woven mat may be bonded to the board insulation with adhesive compounds or
heat by a
10 manufacturer. It is also anticipated that some jobs will require field
application of the non-woven
mat.
A continuous, fluid-conducting channel is created by the non-woven mat. An
advantage
of this non-woven mat is that it conducts the water that penetrates the
exterior layer to weeps
installed at the lowermost level of the wall. Water may then drain from the
structure through the
weeps.
A further advantage of the present embodiment is that any residual water is
dispersed
through the non-woven mat. This residual moisture can be removed as vapor by
ventilation of
the air space that is made possible by the fluid-conducting medium, or non-
woven mat.
Ventilating air is admitted to the air space through stucco starter strips,
EIFS starter strips, and
alternate EIFS starter strips. Each of the starter strips is designed to be
inverted and used also
as a termination strip at the uppermost level of the wall. The weep holes that
provide drainage
of liquid from the air space also serve as vents. Air can flow into the
starter strip weep holes
at the lowermost level of the wall, through the air space created by the non-
woven mat, and
then out the vents created by the weep holes of the invented starter strip
located at the
uppermost level of the wall. It is to be understood that the air space,
because it is continuous,
also provides wind and atmospheric pressure equalization.
It is anticipated that the non-woven mat will limit thermal transfer from the
exterior layer
to the structural wall assembly because the non-woven mat isolates the
cementitious materials
from direct contact with other wall materials.
Another advantage provided by the present embodiment is that the metal lath
can be more
completely embedded into the atucco cementitious material. This improved
integration of the
reinforcing component within 'the exterior layer will strengthen the stucco.
The improved
embedding of the metal lath is the result of the compressibility and porosity
of the non-woven
mat that allows the wet stucco to completely surround the reinforcing metal
lath.
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Similarly, the EIFS coating material and the reinforcing fabric integrate more
completely.
When EIFS exterior layer is applied, trowel pressure forces the coating
material all of the way
through the openings in the reinforcing fabric assuring that the strands are
throughly
encapsulated.
It is believed preferable to fabricate the non-woven mat similar to the mesh
used to form
head-joint weeps and cap vents. However, the non-woven mat may be formed of a
higher
density of thicker fibers resulting in less void space, but also a higher
ratio of binder to fiber. The
reason for higher density and increased binder is to provide a higher and more
uniform lateral
load-bearing capacity with better support for the exterior layer.
Experienced design professionals understand that water will invariably reach
the inner side
of the weather-resistant layer of any building wall assembly system. That
understanding has
prompted designers to search 'for methods and materials to manage that water.
A great deal
of effort has been directed toward developing improved materials that will,
somehow, make the
exterior weather barrier impervious to water. Unfortunately, no effective
integrated water
management system for wall assemblies has been developed prior to the drainage
and
ventilation system novv disclosed. The present embodiment satisfies this
previously unmet
need. It teaches an integrated drainage and ventilation system that prevents
water damage by
providing a practicable water management system. '
This solution may be applied to several popular wall systems. In the most
basic terms, this
system works by providing a continuous conduit that drains water from between
the layers of
any multiple wythe wall assemblly. It also ventilates the conduit by creating
and maintaining an
effective air space.
This integrated syatem uses new methods and materials to create the continuous
conduit.
Non-woven textiles have been adapted for installation at each type of building
component.
These polymer meshes and mats were specifically designed to serve as masonry
cavity mat,
veneer system mat, and vent/weep meshes. These integrated products accomplish
water
management through this interconnected drainage and ventilation system.
BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 shows an exploded isometric view of a preferred embodiment.
Fig. 2 shows a cross-sectional detail of the embodiment depicted in Fig. 1
wherein the
masonry cavity wall terminates at a lintel above a building opening.
Fig. 3 shows a cross-sectional detail of an embodiment wherein the inner wythe
is a stud
structure system.
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Fig. 4 shows a cross-sectional detail of the embodiment depicted in Fig. 1
wherein the
unobstructed air space is more fully illustrated and the air pressure
equalization properties of
the embodiment are shown.
Fig. 5 shows an isometric detail of the embodiment depicted in Fig. 1 taken
along line A-A.
Fig. 6 shows an isometric detail of the embodiment depicted in Fig. 1 taken
along line A-A
wherein the mesh material is not bonded to insulation or other sheet material.
Fig. 7 shows a cross-sectional detail of the mesh holding mortar expressed
from a mortar
joint.
Fig. 8 shows a cross-sectional detail of a masonry wall with a stucco finish.
Fig. 9 shows a cross-sectional detail of a wood framed wall system with a
stucco finish.
Fig. 10 shows a cross-sectional detail of a metal framed wall system with a
stucco finish.
Fig. 11 shows a cross-sectional detail of a masonry wall with EIFS wherein the
non-woven
mat is located between the insulation and the polymer based exterior layer.
Fig. 12 shows a cross-sectional detail of a masonry wall with EIFS wherein the
non-woven
'I 5 mat is located between the masonry and the insulation.
Fig. 13 shows a cross-sectional detail of a wood framed wall system with EIFS
wherein
the non-woven mat is located between the insulation and the polymer based
finish coating.
Fig. 14 shows a cross-sectional detail of a wood framed wall system with EIFS
wherein
the non-woven mat is located between the insulation and the cementitious
sheathing material.
?0 Fig. 15 shows a cross-sectional detail of a metal framed wall system with
EIFS wherein
the non-woven mat is located between the insulation and the polymer based
coating.
Fig. 16 shows a cross-sectional detail of a metal framed wall system with EIFS
wherein
the non-woven mat is located between the insulation and the cementitious
sheathing material.
Fig. 17 shows a~n isometric detail of the non-woven mat termination drain and
vent
:'S extrusion depicted in F=ig. 8.
Fig. 18 shows a~n isometric detail of the non-woven mat termination drain and
vent
extrusion depicted in F=ig. 13 and Fig. 15.
Fig. 19 shows an isometric detail of the non-woven mat termination drain and
vent
extrusion depicted in f=ig. 14.
30 Fig. 20 shows a cross-sectional detail of a metal framed wall system with
EIFS wherein
the non-woven mat is located between the insulation and the polymer based
coating.
Fig. 21 shows an isometric view of the fastener plate depicted in Fig. 11,
Fig. 13 and Fig.
20.
Fig. 22 shows any cut-away isometric view of the embodiment.
:35
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13
DETAILED DESCRIPTION OF THE DRAWING
Fig. 1 shows a masonry cavity wall 10 constructed on a foundation 11 which
supports an
exterior (or second) wythe 12 separated by an air space 14 from an interior
(or first) wythe 15.
The interior wythe 15 may be made of concrete block 16 as shown in Fig. 2,
wood or steel
framing 17 as shown in Fig. 3, or a variety of other materials including, but
not limited to,
structural clay tile, wood, hollow brick, and concrete. The exterior wythe 12
is preferably made
of brick 18 but may be made of other masonry materials including, without
limitation, rock,
artificial stone, concrete, block, stone, glass, and the like. The cavity air
space 14 is provided
with board insulation 19 to which is attached a fluid-conducting medium 20.
This fluid-
conducting medium 20 is a material which allows gases, including air, and
liquids, including
water, to pass through it with negligible resistance but generally prevents
solid materials from
passing through it. The fluid-conducting medium 20 is preferably made of
fabric non-woven mat
bonded to standard extruded or expanded polystyrene foam board insulation 19
as shown in
Fig. 5. The fluid-conducting medium 20 may also be fabricated, sold, and
installed separately
as illustrated in Fig. 6. Although the illustrated fluid-conducting medium 20
is a coarse non-
woven mat, it is to be understood that other equivalent materials and
techniques may be used
in its fabrication. The fluid-conducting medium 20 may be attached to any
materials used to
construct the first wythe. For example, when the side of the first wythe
defining the cavity is
made of gypsum board sheathing 22, the fluid-conducting medium 20 could be
bonded to the
gypsum board or to board insulation 19 as shown in Fig. 3.
The wythes are normally constructed to yield a cavity width of two to four
inches in order
to allow for air circulation and insulation 19 between the wythes; however,
the exact dimension
of the cavity may vary. l3oth wythes of the wall 10 normally rest on a single
foundation 11 which
may be cantilevered or stepped to provide support for the exterior wythe 12.
The foundation 11
is normally covered with a mortar cant 24 which slopes downward from the
cavity side of the
interior wythe 15 to thE: exterior. A masonry flashing 26 communicating
between the interior
wythe 15 and the exterior of the wall 10 rests on a mortar cant 24 so that any
moisture in the
cavity will drain to the exterior oaf the wall 10.
A non-woven polymer mesh 27 may be used to fill drainage openings called
"weeps" 28
which communicate between the exterior of the masonry cavity wall 10 and the
air space 14.
Weeps 28 drain moisture from the surface of flashing 26 and provide
ventilation of the air space
14. Another benefit of unobstructed ventilating weeps 28 and air spaces is
that air pressure is
equalized on both sides of the exterior wythe 12 as illustrated in Fig. 4.
Some design
professionals specify installatioin of additional vents 29 in the upper part
of the exterior wythe
3 5 12 to provide greater circulation of air through the air space 14. Weeps
28 may be made using
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14
a non-woven polymer mesh 27 that is similar to the mesh described for the
fluid-conducting
medium 20, pre-formed plastic devices, cotton wicking, rope, formed sheet
metal components,
tubing, perforated tubing, or simply by excluding mortar from the head joints
of the bricks 18
comprising the first course of bricks in a wall. Weeps 28 and vents 29 are
preferably made with
non-woven mesh 27 to excludE~ vermin. The non-woven mesh 27 preferred for
weeps 28 and
vents 29 is preferably more dense than the mesh from which the fluid-
conducting medium 20
is made and, in the case of the weeps 28, made using a binder that is
resistant to ultra-violet
fight and photochemic<31 oxidation. As with the mesh used for the fluid-
conducting medium 20,
the mesh used for the weeps 28 and vents 29 will preferably be self-
extinguishing and have the
following additional properties: mildew resistance, fungi resistance, flame
spread resistance,
and smoke production resistance,.
The wythes are secured together with steel masonry ties 30 and attachment eyes
32. The
masonry ties 30, eyes 32, and horizontal reinforcing 34 and any other steel
components used
in construction must b~e kept free of moisture to prevent rust. If steel
components of masonry
construction oxidize, expansion results which can, in turn, cause destructive
cracking of
masonry and loss of structural integrity.
In the usual cavity wall 10 construction, an interior wythe 15 is made of
concrete block 16
to which board insulation 19 is affixed. Sealant 36 is applied to all joints
38 and penetrations 40
of the board insulation 19 including, for example, those made by the masonry
ties 30 and eyes
2 0 32.
The exterior wythe 12 is usually face brick 18 secured in mortar 44. When the
brick is laid
by the mason, mortar 44 may be expressed from between the bricks. The mason
removes
excess mortar 44 from the exterior of the brick wythe. The fluid-conducting
medium 20 holds
any mortar 44 expressed from between the bricks in its interstices as shown in
Fig. 7. Mortar
44 and other construction debris is thereby prevented from falling into the
cavity air space 14
and obstructing it or the weeps 28.
Fig. 8 through Fig. 22 show a new alternative to the masonry-finished cavity
wall system
10. This alternative may be described generally as a trowel-applied,
cementitious, veneer wall
assembly 60 that is finiahed with stucco 62, EIFS 64 or similar materials.
Conventional stucco
62 and EIFS 64 walls can be damaged by water penetration when the installation
does not
provide specific provisions for removing water and venting water vapor to the
atmosphere.
Features of the cavity uvall drainage and ventilation system of this
disclosure make it possible
to improve the performance of the veneer wall assembly 60.
Fig. 8 shows a vE;neer wall assembly 60, specifically, a concrete block 16 and
stucco 62
wall. The wall in Fig. 8, unlike previous concrete block 16 and stucco 62
walls, incorporates an
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air space 14 between 'the exterior layer made by the stucco 62 and metal lath
66, and the layer
made by the framing 17 and board insulation 19. The air space 14 is created
and maintained
by installing a semi-rigid, partially compressible fluid-conducting medium, or
non-woven mat,
68 adapted for use in construction of a veneer wall assembly 60. The framing
17 may be
5 mechanically attached to the concrete block 16 using standard masonry
fasteners 70. Board
insulation 19 may be press-fit within the metal framing 17. Metal lath 66 is
held in place using
standard, self-drilling, sheet metal fasteners 74 that connect it to the
framing 17.
Metal grounds 76 are typically used to provide perimeter termination for the
stucco 62.
Although other terminations for stucco 62 may be employed, the term metal
grounds 76
i~ 0 includes, for the purposes of this disclosure, all stucco 62
terminations. The system of the
present disclosure provides an additional starter strip 78 at all bottom edges
of the stucco 62
installation that receives and secures the metal grounds 76.
Fig. 17 presents a detail of the starter strip 78 shown in Fig. 8. The starter
strip 78 can also
be inverted to serve vvith an upper metal grounds 76 to assure that clear
openings will be
15 provided to remove moisture arid other vapors. The starter strip 78 is
attached to the concrete
block 16 with masony fasteners 70 and has a channel 80 to secure the bottom
edge of the
board insulation 19. A drip edge 82 extends downwardly from the bottom surface
of the starter
strip 78. Weep holes 84 perforate the bottom surface of the starter strip 78.
Water that
penetrates the exterior finish layer of the veneer wall assembly 60 flows down
the board
insulation 19 or through the non-woven mat 68 and passes to the outside of the
structure
through the weep holes 84 that are formed through the web of the channel 80
and through the
flange 85 that secures. the mel:al grounds 76. Water is shed from the drip
edge 82 onto the
metal flashing 88. Additionally, an air infiltration barrier 86 may be
installed either adjacent the
concrete block 16 or between the non-woven mat 68 and the board insulation 19.
In Fig. 9, an improved wood frame 17 stucco 62 system is disclosed. A vapor
barrier 90
may be installed as required by a design professional on either side of the
batt or other type of
stud space insulation 92. Wood sheathing 94 and cementitious sheathing 96 or
gypsum board
sheathing 22 may be installed according to the specifications of a design
professional to
complete the structural wall assembly 98. The term "structural wall assembly"
denotes the load-
bearing portions of thE; buildinct wall, collectively, excluding the outermost
weather-resistant
layers. The wood frame embodiment incorporates an air space 14 between the
exterior layer
made by the stucco 6's! and metal lath 66, and the layer made by the
cementitious sheathing
96. The air space 14 is created and maintained by installing a non-woven mat
68. Water
removal and stucco 62 termination in the wood frame 17 construction shown in
Fig. 9 is similar
to that described and shown in Fig. 8.
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Fig. 10 illustrates the incorporation of the present embodiment in a steel
frame 17 structure
having a stucco 62 veneer wall 60. Vapor barrier 90, air infiltration barrier
86, stud space
insulation 92 and sheathing materials may be installed as required by project
specifications. The
metal frame 17 embodiment incorporates an air space 14 between the exterior
layer made by
the stucco 62 and metal lath 66, and the layer made by the cementitious
sheathing 96. The air
space 14 is created and maintained by installing a non-woven mat 68. Water
removal and
stucco 62 termination in the metal frame 17 construction shown in Fig. 10 is
similar to that
described and shown iin Fig. 8.
Fig. 11 depicts an EIFS 64 veneer wall assembly having a concrete block 16
structural
system. Board insulation 19 is mechanically attached to the concrete block 16
in accordance
with the specification of the EIF:S 64 manufacturer. In the present
embodiment, the non-woven
mat 68 is preferably bonded to the exterior side of the board insulation 19
prior to delivery at
the construction site. Masonry fasteners 70 extend through the board
insulation 19 and fastener
plates 100 to secure the non-woven mat 68 and the board insulation 19 to the
concrete block
16 structural system. The fastener plate 100 is corrugated or otherwise shaped
to provide
secure attachment performance with minimal compression of the non-woven mat
68. Air
infiltration 86 and vapor barrier 90 products may be installed in accordance
with the
specifications of the responsible design professional.
The mat/insulation assembly of the present embodiment would be overlaid by
reinforcing
fabric 102 made or specified by the EIFS 64 manufacturer. It is anticipated
that bonding the
reinforcing fabric 102 to the non-woven mat 68 opposite the board insulation
19 will improve the
adhesion and the tensile strength of the EIFS 64 coatings. This improvement
will result because
the non-woven mat separates the reinforcing fabric 102 from the solid surface
of the board
insulation 19 and allow:; the EIFS 64 finish materials to penetrate and
completely encapsulate
the reinforcing fabric 102.
In Direct-Applied E=xterior F=inish Systems (DEFS), EIFS 64 coatings are
normally applied
directly to the sheathing material instead of to the board insulation 19.
Performance of DEFS
may be similarly improved by interposing the non-woven mat 68 between the
sheathing and the
reinforcing fabric 102.
Another method of EIFS 64 construction that is similar to methods currently
promoted by
manufacturers is set forth in Fig. 12. In this method, the non-woven mat 68 is
interposed
between the concrete block 16 structural system and the board insulation 19.
The EIFS 64
materials are applied directly to the board insulation 19 and any reinforcing
fabric 102 specified
by the manufacturer. Board insulation 19 is affixed to the structure with a
fastening system 103
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17
specified by the E1FS 64 manufacturer. Vapor barrier 90 and air infiltration
86 aspects of this
embodiment are like those described for Fig. 11.
Fig. 13 presents a wood framed 17 EIFS 64 veneer wall 60. The wood framing 17
has
gypsum sheathing 22. The EIFS 64 materials are applied to the reinforcing
fabric 102 and the
non-woven mat 68 as described and depicted in Fig. 11. In this embodiment, the
non-woven
mat 68 is bonded to thE: board insulation 19 and the reinforcing fabric 102 is
bonded to the non-
woven mat 68 prior to delivering the insulation to the construction site. The
board insulation 19
is affixed to the framing 17 and/or sheathing 22 with fastener plates 100
(shown in detail in Fig.
21) and wood fasteners 104 specified by the EIFS manufacturer. The air
infiltration barrier 86
and vapor barrier 90 are shown in suggested locations, but, again, would be
installed in
accordance with project specifications.
The ventilation and drainage system of the EIFS 64 system of the present
disclosure
provides an architectural shape, preferably an extrusion, to terminate and
ventilate the EIFS 64
at the top of the wall aind to provide an EIFS starter strip 106 at all bottom
edges of the EIFS
64 installation. Top and bottom extrusions may be similar or identical but
inverted. Fig. 18
presents a detail of the EIFS starter strip 106 that is attached to the
framing 17 with wood
fasteners 104. The EIFS starter strip 106 has a channel 80 to secure the
bottom edge of the
board insulation 19 and a separate mat channel 107 for receiving and securing
the non-woven
mat 68. A drip edge 8:! extends downwardly from the bottom surface of the
starter strip 106.
Weep holes 84 perforate the bottom surface of the channel 80 and the mat
channel 107 of the
EIFS starter strip 106. Water flows through the non-woven mat 68 and passes to
the outside
of the structure through the weep holes 84 and drips from the drip edge 82
away from the
foundation 11 or other structural features.
Fig. 14 shows a wood framed 17 structure with wood sheathing 94 and
cementitious
sheathing 96. The features of the wall system of Fig. 14 are like those
depicted in Fig. 12 with
cement block 16 being replaced with wood framing 17, wood sheathing 94, and
cementitious
sheathing 96 or gypsum sheathing 22. The board insulation 19 would be overlaid
by reinforcing
fabric 102 made or specified by the EIFS fi4 manufacturer. It is anticipated
that locating the
non-woven mat 68 bei:ween the board insulation 19 and the sheathing will
provide superior
moisture removal and ventilation compared to systems now known in the art. The
board
insulation 19 will be omitted in installations such as DEFS. Placing the non-
woven mat 68
between the sheathing and the reinforcing fabric 102 is expected to enhance
the performance
of the DEFS installations in the same way that EIFS performance is improved by
increasing
ventilation and moisture drainage with the non-woven mat 68 disclosed herein.
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18
Fig. 15, summarizes the entire system of the present disclosure by depicting a
commonly
employed wall assembly in which masonry construction is used on the lower
elevations and
frame 17 construction with Elf=S 64 is used at higher elevations. Economies
are achieved by
reducing the amount of heavy masonry elements that must be conveyed to
elevated areas of
the building. The lighter EIF;S 64 materials are installed more quickly and
easily than is
masonry. However, the transition from one construction system to another
creates a region with
greatly increased likelihood for water penetration. The present embodiment
prevents moisture
problems with integrated drainage and ventilation systems. Mortar 44 bridging
between the
brick 18 and the board insulation 19 is prevented by the fluid-conducting
medium 20 which
holds extruded mortar' 44 proximate to the exterior wythe 12. The air space 14
maintained by
the fluid-conducting medium 20 communicates with the exterior of the structure
through the
non-woven polymer mesh 27 that is incorporated in the vents 29. The interior
wythe 15 supports
the wood or steel framing 17 wised with the veneer wall assembly 60.
Wood or steel framing 17 terminates the masonry cavity wall 10 with metal
flashing 88 at
the top . Rain shed from the exterior surface of the veneer wall assembly 60
drips from the EIFS
starter strip 106 onto the metal flashing 88, as does water removed from the
interior of the EIFS
64 (or stucco 62, not shown) by means of the non-woven mat 68. Wood sheathing
94, gypsum
sheathing 22, and stud-space insulation 92 are protected from moisture
penetration by the
embodiment disclose~9 herein. As with the descriptions associated with all
figures, the air
~0 infiltration barrier 86 and the vapor barrier 90 must be provided as
required by contract
specifications.
Fig. 16 shows the' embodiment disclosed for the EIFS configuration details of
Fig. 12 and
Fig. 14 as applied to steel frame 17 building wall assemblies.
Fig. 17 shows an isometric detail view of the stucco 62 starter strip 78.
?5 Fig. 18 shows an isometric detail view of the EIFS starter strip 106.
Fig. 19 shows an isometric: detail view of an alternate EIFS starter strip 108
that is adapted
for use in installations in which the non-woven mat is situated between the
board insulation 19
and the cementitious sheathing 96. The alternate EIFS starter strip 108, like
the EIFS starter
strip 106 and the stucco G2 starter strip 78, may be inverted and used as a
termination strip at
:30 the top of the veneer wall assembly 60.
The interrelationship of the insulation holding channel 80, the weep holes 84
and the drip
edge 82 are more readily seen in Figs. 17-19 than is possible from the section
details of Figs.
8-16.
Fig. 20 shows the' embodiment disclosed for the EIFS configuration details of
Fig. 11, Fig.
:35 13, and Fig. 15 as applied to steel frame 17 building wall assemblies.
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19
Fig. 21 shows an isometric detail view of the specially designed fastener
plate 100 that is
adapted to hold the board insulation 19 equipped with reinforcing fabric 102
and non-woven mat
68 to the various builoling wall assemblies that incorporate EIFS.
Fig. 22 shows, in an isometric detail view, the wall assembly shown in the
elevational
cross-section of Fig. 15. Fig. 22 shows the generalized configuration that
incorporates the
component materials comprising the present embodiment.
Changes and modifrcations in the specifically described embodiments can be
carried out
without departing from the scope of the invention which is intended to be
limited only by the
scope of the appended claims.
INDUSTRIAL APPLICABILITY
From the foregoing description, it can be readily seen by those skilled in the
art that the
methods and articles disclosed have general applicability in the building
construction industry.
20
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LIST (~F DRAWING REFERENCE NUMBERS
10 masonry cavity wall 66 metal lath
11 foundation 68 non-woven mat
5 12 exterior (or second) wythe70 masonry fasteners
14 air space 74 self-drilling sheet
metal screws
15 interior (or first) wythe76 metal grounds
16 concrete block 78 starter strip
17 wood or steel framing 80 channel
10 18 brick 82 drip edge
19 board insulation 84 weep holes
20 fluid-conducting medium 85 flange
22 gypsum board sheathing 86 air infiltration barrier
24 mortar cant 88 metal flashing
15 26 masonry flashing 90 vapor barrier
27 non-woven polymer mesh 92 stud space insulation
28 weeps 94 wood sheathing
29 vents 96 cementitious sheathing
masonry ties 98 structural wall assembly
20 32 attachment eyes 100 fastener plate
34 horizontal reinforcing 102 reinforcing fabric
36 sealant 103 fastening system
38 joints 104 wood fastener
penetrations 106 EIFS starter strip
25 44 mortar 107 mat channel
60 veneer wall assembly 108 alternate EIFS starter
strip
62 stucco
64 EIFS
