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| Topic:
Locating CMU Control Joints (CJ's) |
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Question:
What is the approximate spacing of Control Joints (CJ’s)
for reinforced CMU?
Answer:
Using the Empirical Method in NCMA TEK 10-2B, Table
1 calls for a length to height ratio of 1.5 not to exceed
25ft. This assumes you have wire every 16” o.c.
The engineering method in NCMA TEK 10-3 has different
ratios but still does not exceed 20 or 25 ft.
Kelly L.K. Walker
Architectural Services Director
Masonry Institute of Michigan, Inc.
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| Supporting
Documents: |
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NCMA
TEK 10-2C
Control Joints For Concrete Masonry
Walls - Empirical Method
Click
here for Tek Note
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NCMA
TEK 10-3
Control Joints For Concrete Masonry
Walls- Alternative Engineered Method
Click
here for Tek Note
www.ncma.org
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| Topic:
Locating Brick Veneer Expansion Joints (EJ's) |
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Question:
What is the approximate spacing for Expansion Joints
(EJ's) for a typical brick veneer application?
Answer:
Please read the following supporting documents.
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Supporting
Documents:
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BIA
Tech Note 18A
Accommodating Expansion of Brickwork
Click
here for Technical Note
www.gobrick.com
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Brick
Expansion Joints and
Wall Openings
By: J Gregg Borchelt, PE
Courtesy of The Story Pole
Click
here for article |
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| Topic:
CMU Wire Reinforcing |
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Question:
What is the best wire for Single Wythe CMU and for
Multi-Wythe CMU Cavity Wall?
Answer:
Contrary to popular
belief, wire reinforcing today typically offers no
structural stability. In fact, the primary purpose
of wire reinforcement in modern masonry wall systems
is simply to help resist CMU shrinkage cracking. Typically,
vertical and bond beam rebar reinforcement serves
to resist wind loading.
Truss
wire is not recommended for use is reinforced CMU.
Diagonal cross rods make it impossible to meet modern
grouting standards referenced in the IBC and sub-referenced
in ACI Building Code Requirements for Masonry Structures.
Ladder wire with cross rods spaced 16 inches on center
allows code required centering of rebar, freer flow
of grout and promotes full embedment in mortar at
every intersection where side and cross rods meet
on the inner and outer CMU face-shell, resisting wall
shrinkage.
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Supporting
Documents:
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Climb
the Ladder
To
Improve Wall Reinforcing Design
Written
by Kyle Lochonic & Jeff Snyder
and is published in the Masonry Magazine.
Click
here for article |
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Building
Code Requirements and
Specification for Masonry Structures
Reported by the Masonry Standards
Joint Committee (MSJC)
Click
here for Building Code Requirement
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NCMATEK
12-2B
Joint Reinforcement
For Concrete Masonry
Click Here for Tek Note
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NCMA
TEK 12-1A
Anchors and Ties for Masonry
Click
here for Tek Note
www.ncma.org
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| Topic:
CMU Wire Reinforcing |
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Question:
Is wire reinforcement with 3/16 inch diameter side rods
or 3/16 inch diameter side and cross rods better than
standard 9 gauge side and cross rods?
Answer:
No, for the most part it is just the opposite. The primary
purpose for wire in todays reinforced walls is to reduce
CMU wall shrinkage. It is very difficult to surround
3/16 inch diameter wire with mortar when placed in 3/8
inch bed joints. This is especially evident when considering
allowed tolerances for masonry units and joint sizes.
Mortar better surrounds wire when utilizing 9 gauge
flush welded side and cross rods, increasing resistance
to shrinkage cracking. It is no surprise demand for
truss wire has fallen significantly in the last decade.
The market simply demands higher performance 9 gauge
16 inch core-clear ladder!
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| Supporting
Documents: |
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TECH
Talk
Daniel S. Zechmeister, P.E.
Executive Director
Masonry Institute of Michigan, Inc.
Click
here for article
www.mim-online.org
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Selecting
the right reinforcement for the job
Mario J. Catani
Click
here for article
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