| |
Frequently Asked Questions |
|
|
1)
How do I recognize a stability problem with the existing veneer
anchors?
2) What are causes to veneer anchorage issues
that cause instability?
3) What options does a building owner have when
confronted with a bulging or cracked veneer?
4) What are the re-anchoring ties or anchors intended
to do?
5) What type of anchors are available to re-connect
an unstable veneer?
6) How do I select an anchor for my re-stabilization
application?
7) Is there one anchor that can be used for all
applications?
8) What tools and equipment are necessary to install
various retrofit anchor types?
9) Will any of these anchors draw together walls
that are separating?
10) Why not use a mechanical expansion anchor
to re-attach the walls?
11) How often do the re-anchoring ties get spaced
in the veneer?
12) Why do you recommend “rotation only”
when drilling through the masonry?
13) Is there any exposed hardware with any of
the CTP anchors after they are installed?
14) Why not manufacture the anchors of carbon
steel?
15) Why not use all thread rod that goes through
the width of the wall and is nut and washered from both sides?
16) Wouldn’t it be better to just tear
down the veneer and re-build it?
17) Why re-anchor if the building has lasted
many years with errors or has been diagnosed with a possible
issue?
18) Will a re-anchoring system add benefit in
seismic related areas of the country?
19) Why “stitch” a cracked veneer?
20) Is field testing of restoration anchors always
necessary?
21) Do I have to have the building façade
inspected?
22) Are there installation time guidelines that
can be used for estimating purposes? |
|
|
|
|
|
|
1)
How do I recognize a stability problem with the existing veneer
anchors? |
|
|
|
a) Look
for excessive wall movement. Most anchors and ties are manufactured
with a code limit of free play; distance beyond this dimension
deserves attention. (see picture 1,
2
and 3)
b) The veneer moves when pressure is applied.
Loading applied to the veneer should not exceed code allowable
limits of wall movement or tie deflection.
c) Check around doors and windows for obvious
gaps in the wall. (see pictures 1
,2
and 3)
d) Cracks at corners that show wall movement.(see
picture 1,
2 and 3)
e) Bulges at shelve angles or large wall
segments. (see picture)
f) Fallen panels of brick or stone
g) Rust staining on the mortar joint form
the ties (see picture)
h) Open segments of the wall and probe
the cavity. If the wall is built within standards, a tie
should be present within code requirements.
i) Shards of stone at joints pop from the
veneer
|
|
|
|
|
top of page |
|
|
|
2)
What are causes to veneer anchorage issues that cause instability? |
|
|
|
a) Over
half the experiences encountered relate to the lack of wall
ties. That is, either an insufficient quantity or the complete
omission of ties. Next would be corrosion related decay
of the tie.
b) Corrosion exemplified by rust and decay
of the tie. When one considers that the use of hot dip galvanized
anchors weren’t popular until the mid to late 80’s,
there are a number of structures with ties that are mill
galvanized or brite basic. But corrosion can also be a result
of galvanic activity. The combination of differential materials
is the culprit in this case. With this circumstance the
less noble element is attacked such as stainless with carbon
steel whereby the carbon steel is sacrificed in the presence
of moisture. (see pictures 1
, 2, 3
and 4)
c) Improper anchor types or sizes can be
over stressed and cause problems. Undersized anchors that
are to light a gauge may have been used. Current wind loading
may have changed within the buildings effective perimeter
due to code changes, or new building neighbors that enhance
wind speed. (see
picture)
d) Poor quality products or construction
techniques can create an un-stable condition. Unfortunately
things happen and substitutions may have taken place that
was less substantial then required. Other situations such
as high absorption brick may have been used, insufficient
or poorly sized control joints, inadequate or ineffective
soft joints, suspicious mortar quality, improper fasteners
to the structure for the tie, etc are examples of various
quality issues. (see pictures 1,
2,
and 3)
e) Differential wall movement created by
the differences in thermal response of the material can
create an instability problem. Double wythe walls with brick
headers can become unstable if the header should crack due
to excessive wall movement between the inner and outer wythe.
Parapets under-go major temperature swings between the outer
face wall and inner most structure. If not designed properly,
dislocation of the wythes are possible. (see pictures 1
and 2)
f) Other less obvious issues are related
to environmental decay, such as acid rain. Also, chemicals
used improperly to wash down the masonry can attack the
existing ties over time.
|
|
|
|
|
top of page |
|
|
|
3)
What options does a building owner have when confronted with
a bulging or cracked veneer? |
|
|
Some attention
to the bulge and crack is required. Usually bulges occur
at shelve angles or relief angles. The cause can be associated
with the lack of adequate fastening, undersize anchor bolts,
improper installation, an undersize shelf angle, etc. Cracking
can be associated with improper jointing details, poor quality
or high absorption brick, poor mortar, differential wall
movement, base structure shrinkage, excessive building drift,
inadequate ties, no ties, rusting, etc. This will need repair
and the partial removal of brick about the angle can be
necessary. A licensed engineer must evaluate the conditions
and determine an appropriate remedial action. However, the
undisturbed masonry should be re-anchored to avoid shifting
of the wall during reconstruction, or to re-anchor a veneer
that has shifted beyond its plastic limits
|
|
|
|
|
top of page |
|
|
|
4)
What are the re-anchoring ties or anchors intended to do? |
|
|
|
One must first
remember that during construction, the ORIGONAL tie or anchor
was designed to act as a load transferal system between
the veneer and the back-up. In order to prevent the veneer
from deflecting excessively, ties are spaced at predetermined
intervals that transfer the live load of the veneer to the
structural back-up. This maintains a somewhat rigid facade
that will repel the elements of wind, rain, snow and ice
from the occupants. An unstable veneer is subject to excessive
deflection which causes cracking and will lead to excessive
moisture penetration. This scenario will lead to other issues
such as mold, mildew, or corrosion of other building elements.
A restoration anchor will need to resist live loads, transfer
the loads to the back-up structure, add stiffness to the
veneer and sustain a long term design life for the structure.
Structural engineers in your local would be most familiar
with the live load criteria’s. An anchoring selection
can then be made.
|
|
|
|
|
top of page |
|
|
|
5)
What type of anchors are available to re-connect an unstable
veneer? |
|
|
|
There are choices
from which to select. There are self-threading types (Stitch-Tie)
that thread the wythes together; friction pins that connect
via forced entry; mechanical anchors that are activated
via torque or hammer set to create an expansion connection
in the base material (Torque-Tie, Panel-Tie); chemical anchors
that use epoxies and wire mesh screens for adhering the
wythes together; cement based injection anchors that utilize
proprietary socks to create an intimate bond with the sub-strata.
Anchoring technology is continuously changing with more
scientific advances being made. Maintain a current contact
profile with CTP in order to stay current with new products
|
|
|
|
|
top of page |
|
|
|
6)
How do I select an anchor for my re-stabilization application? |
|
|
|
There are three
primary functions to consider for anchor replacement. The
architect/owner is concerned with aesthetics, the engineer
fulfills functional criteria’s, and the contractors
are concerned about installation requirements. Each anchor
type has its plus and minuses. That is, the easiest to install
may NOT be the best functionally to withstand the working
environment. Conversely, the most formidable system may
be the most elaborate to install which will drive the installed
cost beyond acceptable limits. The type of veneer and quality
of the veneer influence our decision. A large mortar joint,
butter joint, soft joints, solid brick, block veneers, stone
veneers, terra-cotta, precast, stucco veneers, etc are typical
examples of product decision choices. The back-up material
is just as important as the veneer. Is the back-up brick,
solid block, hollow block, concrete, steel, metal stud,
wood stud, sheathing, multi-wythe material, etc, influence
the style and type of anchorage one needs to use for selection
purposes. Call our Tech services for guidance.
|
|
|
|
|
top of page |
|
|
|
7)
Is there one anchor that can be used for all applications? |
|
|
|
Unfortunately
not. Each application requires a thoughtful understanding
of the requirements for anchorage then the anchoring system
features need to be matched to satisfy various functional
requirements that are influenced by the application. Situations
such as bending, positive attachment to metal stud, size
limitations, job site quality assurance testing, tensile
capacity, edge distances, mortar quality, back-up quality,
cavity depth, anchorage depth, quantity of anchors, etc;
all play into the selection process. Contact Tech services
for guidance.
|
|
|
|
|
top of page |
|
|
|
8)
What tools and equipment are necessary to install various retrofit
anchor types? |
|
|
|
a)
Stitch-Tie - Hammer drill; rotary hammer; appropriate Stitch-Tie
setting tool; carbide drill bit
b) Toque-Tie - Hammer drill OR rotary hammer;
carbide bit OR steel drill bit; Torque-Tie setting tools;
torque wrench
c) Panel-Tie – Hammer drill OR rotary
hammer; carbide OR diamond counter bore bit; carbide OR
steel drill bits; Anchor setting tools;
|
|
|
|
|
top of page |
|
|
|
9)
Will any of these anchors draw together walls that are separating? |
|
|
|
No. The intent
of any of these anchors is to stabilize the veneer at its
current location. Attempting to draw the walls together
may cause cracking damage to the wall.
|
|
|
|
|
top of page |
|
|
|
10)
Why not use a mechanical expansion anchor to re-attach the walls? |
|
|
|
Anchors of this
style are designed and intended to “clamp” the
work (in this case the wall) to its sub-structure. The clamping
forces exert a significant tension or preload on the fastener
and the reaction must be absorbed by the contact material-
the veneer. These clamping forces will crack the wall and
not restrain it.
|
|
|
|
|
top of page |
|
|
|
11)
How often do the re-anchoring ties get spaced in the veneer? |
|
|
|
Consult with
local codes for limits. If none exist, an engineer of record
can calculate the maximum spacing criteria’s. However,
a Stitch-Tie is typically spaced at one per 2 square feet
of veneer to be anchored. The Torque-Tie is usually spaced
at one tie per 4 square feet of veneer. Panel-Tie anchors
are usually no less then two per stone panel but actual
quantities are very application specific. Please contact
Tech services for assistance.
|
|
|
|
|
top of page |
|
|
| 12)
Why do you recommend “rotation only” when drilling
through the masonry? |
|
|
The hammering
action of a rotary hammer can cause significant damage to
the existing masonry. Most rotary hammers are developed
to drill into concrete whereby the chiseling intensity and
frequency aid the driller for efficient and quality drilling.
Drilling in masonry is more complicated. The veneers are
typically a 4” nominal thickness and the chiseling
action of the bit can dislodge the intimate mortar contact
between the brick and mortar. Field studies have shown the
mortar on the exiting side of the drilled joint tends to
be blown out sometimes half its distance from the joint
if too aggressive rotary hammer and pressure are applied.
Obviously, drilling fast saves time and money, however,
the performance of any anchoring system is function of its
embedded contact area. The less material we have to anchor,
the weaker the connection. There are many quality hammer
drills (3-jaw chuck type drills) that do not destroy the
hardened masonry and the installer is encouraged to try
the tool best suited for the application. Contact Tech services
for tool information.
|
|
|
| |
|
|
top of page |
|
|
| 13)
Is there any exposed hardware with any of the CTP anchors after
they are installed? |
|
|
All the anchors
are designed to be sub-surface when installed. No hardware
or scars are obvious when a re-anchoring application is
completed. This is an appealing feature with any of the
CTP products that are developed for façade re-anchoring.
|
|
|
| |
|
|
top of page |
|
|
| |
14)
Why not manufacture the anchors of carbon steel? |
|
|
| |
In many applications,
we face issues other than the lack of anchors as apart of
the façade repair scenario. Excessive moisture migration
into the cavity is a common problem with distressed veneers.
The excessive moisture can contribute to the accelerated
corrosion of the tie. The re-placement anchor should have
qualities that exceed original expectations and provide
for a long term solution. Austenitic stainless steel and
brass have proven to be a stable material that solves functional
requirements of the anchor and provides for a long term
anchoring solution.
|
|
|
| |
|
top of page |
|
|
| |
15)
Why not use all thread rod that goes through the width of the
wall and is nut and washered from both sides? |
|
|
| |
Fish plates,
or through wall bolting, does not restrain the veneer in
both directions. Wind loading on the veneer creates a suction
or compression force on the veneer. The intent of the ties
is to absorb theses forces and transfer them to the base
structure. The ties are to be stiff enough to limit veneer
deflection which will limit cracking. Through-bolts only
keep the wall from further separation and do little to function
as an effective wall tie. They become a maintenance issue
and an obtrusive projection from the face of the facade.
|
|
|
| |
|
top of page |
|
|
| |
16)
Wouldn’t it be better to just tear down the veneer and
re-build it? |
|
|
| |
A veneer condition
assessment by a licensed engineer should be performed in
order to determine the course of action. The cost of tear
down is an EXPENSIVE alternative and the replacement often
lacks the heritage of the former veneer.
|
|
|
| |
|
top of page |
|
|
| |
17)
Why re-anchor if the building has lasted many years with errors
or has been diagnosed with a possible issue? |
|
|
| |
It’s just
a matter of time. Obvious signs (cracks, bulges, rusted
ties) are warnings and shouldn’t be taken lightly.
A fortified veneer will add life and safety to an existing
façade.
|
|
|
| |
|
top of page |
|
|
| |
18)
Will a re-anchoring system add benefit in seismic related areas
of the country? |
|
|
| |
Yes. The addition
of restoration anchors will add stiffness and strength to
the existing veneer anchoring system. This provides a benefit
to the anchored façade by adding retention capabilities
to the existing veneers and by upgrading insufficiently
tied veneers with additional support and retention. Contact
Tech Services for assistance with seismic qualifications
and products capable of establishing a seismic connection.
|
|
|
| |
|
top of page |
|
|
| |
19)
Why “stitch” a cracked veneer? |
|
|
| |
First the determination
of the cause of the crack is important. Assuming the cracking
is a typical stair step opening originating at the corner
of a window or door, the crack will most likely be associated
with rusting lintels. The volume of rust created by the
oxidation of the steel is greater than the original steel
thickness. Much similar to an ice crystal that dislodges
objects due to the volume of ice created. Cracking such
as this creates a discontinuity of the veneer and allows
excessive moisture to the cavity while possibly creating
a structural issue with the brick veneer. Caulking will
seal the crack; however, the monolithic nature of the veneer
is still compromised. A Stitch-Tie repair technique is available
that can re-connect the disjointed veneer. Contact our Tech
Services for assistance and repair technique.
|
|
|
| |
|
top of page |
|
|
| |
20)
Is field testing of restoration anchors always necessary? |
|
|
| |
The decision
depends on the experience of the engineer, the quality of
the “as-built” structure, the size or quantity
of anchors, and the experience of the installer. Testing
should be performed by third party professionals as part
of the project requirements. Pre-bid testing by the manufacturer
creates a comfort level of the product choice and quantifies
the anticipated performance characteristics of the anchor.
Axial tensile loading as well as deflection under load are
important considerations to a field test. We perform this
service for successful bidders or as a pre-qualification
process. Contact Tech Services regarding your request for
testing and the testing criteria’s we follow. (see
picture)
|
|
|
| |
|
top of page |
|
|
| |
21)
Do I have to have the building façade inspected? |
|
|
| |
Unless your building
is in New York City, Columbus, Boston, LA, Chicago, or Milwaukee,
there are no laws requiring a façade inspection.
However, that doesn’t make the problem go away. These
locations have instituted an aggressive program of facade
inspection for the benefit of public safety, to add value
to the public domain, and to preserve our buildings historic
legacy for years to come. Check with local building authorities
regarding façade inspection requirements
|
|
|
| |
|
top of page |
|
|
| |
22)
Are there installation time guidelines that can be used for
estimating purposes? |
|
|
| |
As the manufacturer
and supplier, we evaluate installation time for general
proposes. The time to install an anchor is dependent on
the knowledge and capabilities of the installer, the quality
of the tools and equipment used, and the nature of the anchoring
location. That is, a vertical pinning scenario is very cost
effective versus a horizontal pinning pattern on a multi-story
structure. The type of work platform is important as well.
A swing stage versus a pipe scaffold or mast climber is
more difficult since the footing is less firm. The type
of anchor method can also vary installation time. If one
were to ignore the effects of footing, travel time on a
rig, or other job related interferences with anchor installations,
a Stitch-Tie for instance can be installed within 2 to 3
minutes per anchor. Hollow block backup the quickest and
concrete back up more time consuming. A Torque-Tie can take
3 – 4 minutes per anchor but solid back up is quicker
and the use of a cordless screw gun can cut the time substantially.
|
|
|
| |
|
top of page |
|
|