16-Composite and Cavity Wall Study Guide - Career Institute of ...

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CAREER INSTITUTE OF TECHNOLOGY

STUDYGUIDE

CHAPTER 16
:

COMPOSITE AND CAVITY WALLS

INSTRUCTOR
:

Mr. Brian Iasiello


USEFUL INFORMATION


1.

Not only are masonry composite walls and cavity walls chosen for their

strength, but their resistance to rain, fire, an
d sound transmission keep

these two wall designs at the forefront of popular wall selections.


2.

The designs for composite walls and cavity walls are similar. Both are

multiwythe masonry walls, two separate wythes of different masonry

units, with each wyt
he having different properties and strengths.


3.

Tying the wythes together with joint reinforcement and insulating the

air cavity between them creates excellent exterior structural bearing

walls.


4.

Frequently, aesthetically appealing low
-
maintenance bri
ckwork is used

for the outside wythe and cost
-
saving concrete masonry units are used

for the inside wythe, also becoming the interior wall face.


5.

Although similar, there are differences between composite walls and

cavity walls, affecting both their phys
ical properties and selection in

wall design.


6.

Successful performance of cavity walls and composite walls depends on quality workmanship
and attention to details such as wire joint reinforcement, control and expansion joints, and
flashing and weeps.


Te
rms



Adjustable A
ssemblies

-

Masonry w
all reinforcement consisting of
ladder
-
type or truss
-
type
rein
forcement embedded in the inner
wythe with exte
nded tabs or eye hooks to which
rectangular
adjustable sections are connected and embedded in the joints
of
the
outer wythe.


Bearing P
lates

-

Steel plates with welde
d anchors on their bottom sides
embedded in the tops of
masonry bearing walls to which structural

steel beams or joists are secured by welding.

Bond B
eam

-

A horizontal reinforced beam comprised

of s
pecially formed
bond beam concrete
masonry units,

grout, and horizontally placed
steel reinforcement bars designe
d to strengthen a
wall, support
loads above openings, or distribute imposed loads uniformly.


Cap

-

An architectural concrete or stone mem
ber f
or part of or an entire
wythe that is terminated
below the top of an adjoining wall.


Capital

-

An architectural concrete or s
tone top for piers and columns,
protecting them from the
weather and enhancing their appearances.


Cavity W
all

-

A masonry wall co
nsisting

of an inner and an outer wythe
bonded with corrosion
-
resistant met
al ties and separated by an air
space not less than 2


or more than 41

2

.


Cleanouts

-

O
penings in the face
-
side of CMU walls, enabling the removal

of mortar droppings
before grouting.


Composite Masonry W
all

-

A masonry w
all consisting of two wythes of
different masonry
units having dif
ferent strength characteristics
conne
cte
d with corrosion
-
resistant wire
reinforcement or brick
headers and acting as a single wall in resisting forces and loads.


Control J
oint

-

A vertical separatio
n completely through a concrete
masonry wall that is filled
with an inelastic substance contro
lling
the location of cracks caused by
volume changes resulting
in the
shrinkage of block.


Coping

-

The projecting top cap of a wall.


Differential M
ovement

-

The u
nequal movement of the building
materials in a wall system.


Drainage Wall S
ystems

-

Masonr
y wall
s designed to divert water from
their air cavity to the
exterior of the outer wythe.


Drip

-

A cutout in the underside of caps
, copings, and sills preventing
water from traveling back
to and run
ning down the face of the wall,
causing water to drip be
yond the face of the wall.


Expansion J
oint

-

A horizontal or vertica
l separation completely through
a

brick wythe that is
filled with an elastic substance permitting the

expansion o
f brick walls caused by thermal
movements or
increasing volume of brick.


F
ire W
all

-

A fire
-
resistant rated wall usuall
y built within a structure from
the foundation and
extending above
the roof to restrict the spread
of fire from one part of a structure to another.


Granular Fill I
nsulations

-

Lightweight, inorganic, perlite o
r

vermiculite
granules treated for
water repellency and used as wall insulation.


High
-
Lift G
routing

-

Grouting done once a wa
ll is built to its story height
or final height,
whichever is less, in a single pour.

Ladder
-
Type Wire R
einforcement

-

Masonry wal
l reinforcement
c
onsisting

of two or more
longitudinal rod
s welded to perpendicular cross
rods, forming a ladder design.


Load
-
Bearing W
all

-

A wall supporting it
s own weight and the structural
loads, weights, and
forces to which the structure is subjected
.


Low
-
Lift G
routing

-

Grouting done in multiple pours as the wall is built.


Multiwythe Grouted Masonry W
all

-

A m
ultiwythe wall whose air cavity
is filled with grout.


Parapet W
all

-

That part of a wall extending above the roofline.


Rain Screen W
all

-

A

masonry cavity wal
l containing protected openings
permitting the passage
of air but not water into the cavity,

permitting equal air pressu
res of the outside air and that
within the
air cavity.


Rigid I
nsulation

-

Polystyrene materials produced from extrud
e
d foam or
molded bead
processes placed bet
ween the wythes of cavity walls
as wall insulation.


Shelf A
ngles

-

Steel structural member
s on which brick are bedded for
wall support.


Soft J
oints

-

Horizontal expansion j
oints minimizing wall cracks by
permitt
ing both the
expansion

of brick masonry walls and the
deflection of the shelf angles.


Through
-
Wall F
lashing

-

Flashing exte
nding completely across the air
cavity separating
masonry wy
thes and through the outer wall
beyond the exterior face of the wall.


T
r
uss
-
Type Wire R
einforcement

-

Masonry wall reinforcement consisting

of two or more
longitudinal rod
s welded to diagonally oriented
cross rods, forming a truss design.


Wythe

-

A masonry wall.


STUDYGUIDE


A.

Multiwythe Walls
:



1.
Two separate wythes of diff
erent materials


2.

Each with different properties



3.

Tied together with joint reinforcement



4.

Great strength, resistant to fire and moisture, excellent insulator




B.

Comparing Composite and Cavity Walls
:



1.
Composite Masonry Wall
:


a)

Built of two w
ythes of differing masonry units



b)

Connected with corrosion
-
resistant reinforcement



c)

Acts as a single wall


2.
Cavity Wall
:


a
)

Built of an inner and outer wythe connected by corrosion
-
resistant metal ties

and separated by an air space


b)

Differen
t from a composite wall in that the outer wythe resists forces

independently without transmitting stress to

the inner wythe



c)

Cavity walls and composite walls are similar in that they

are both multi
-
wythe

walls, but a 2" or wider air cavity is a di
stinguishing characteristic of cavity walls.


C.

Controlling Moisture
:



1.

Cavity walls are drainage wa
ll systems, as penetrating rain
drains to the bottom and is

diverted to the exterior.

2.

Flashing and weep holes are required.


D.

Insulating Composite and

Cavity Walls
:


1
.
Air cavities may receive insulation.


a)
Granular fill insulations


1)
Poured into cavities




b)
Rigid insulation board


1)
Polystyrene material adhered to the back
-
up wall


E.

Wall Reinforcement
:



1.
Always corrosive resistant, s
uch as hot
-
dipped galvanized or

stainless steel
.

2.
Ladder type


3.
Truss type


4.
Adjustable assemblies


F
.
Accommodating Differential Movements
:


1.
Differential movement is the unequal movement of different building materials in a
wall system.

2.
Expansion joints
allow materials to expand.


3.
Control joints attempt to control crack locations.


G
.
Parapets, Copings, and Caps
:


1.
A parapet wall is that part of a wall above the roofline.

2.
Coping is the projecting top cap of a wall.


3.
A cap is an architectural me
mber for a wythe terminated below the top of an adjoining
wall.


H
.
Grout
-
Reinforced Walls
:


1.
Grout is a mixture of cement, water, and small aggregates.

2.
It is used to strengthen masonry walls
.


3.
Grout is used in conjunction with steel reinforcing rods.