Removing And Replacing Deteriorated Brick Masonry
- Procedure code:
- Hspg Prepared For Nps - Sero
- Brick Unit Masonry
- Last Modified:
REMOVING AND REPLACING DETERIORATED BRICK MASONRY
A. This procedure includes guidance on removing and
replacing deteriorated brick masonry. It should be used
in conjunction with the procedure on repointing historic
masonry. For guidance on repointing, see 04520-02-R
"Repointing Masonry Using Lime Mortar".
B. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
C. For general information on the characteristics, uses and
problems associated with brick, see 04211-08-S.
1.02 PROJECT/SITE CONDITIONS
A. Environmental Requirements:
1. Do not proceed with brick replacement under adverse
weather conditions, or when temperatures are below
or above manufacturer's recommended limitations for
installation; Proceed with the work only when
forecasted weather conditions are favorable for
2. Wet Weather: Do not apply or mix mortar on outside
surfaces with standing water or outside during
3. Cold Weather, winter construction is not allowed
without consent of RHPO; Winter construction when
surface temperature of masonry is below 40o F. or
air temperature is predicted to be below 40o F.
within 48 hours. See #6 below.
4. Hot Weather: The surface temperature of the work,
not the ambient temperature, should not be higher
than 100o F.; Mortar mixing should be done only in
the shade; Cover mortar with water-misted burlap in
hot weather to reduce evaporation; Pointing work
should be done in the shade; Work around the
building during the day so that the fresh work will
be shielded from direct sunlight to reduce
evaporation rate. High temperatures can cause
flash setting of cements and rapid evaporation of
water in the mix, leading to lack of development of
final strength by the cement.
5. All materials must be kept above 40o F.
6. Special Precautions and Notes: Do not allow
masonry to freeze until mortar is thoroughly dry
and hardening almost complete (approx. three days
time); The setting of lime mortar is very much
slower than that of cement mortar because the
curing requires the absorption of carbon dioxide to
form hard lime carbonates; It is a very lengthy
process, so do not expect it to become hard
immediately, especially at the core of large masses
A. Salvaged Brick: Approved by RHPO, sound, crack free,
clean brick without face chips larger than 1/2 inch,
salvaged from removal of removed face brick work of same
B. Replacement Brick: Approved by RHPO.
C. Brick slips: Approved by RHPO.
D. Mortar to match existing (see 04100-03-S "Preparing Lime
Mortar for Repointing Masonry").
B. Joint tools
F. Stiff bristle brushes
A. Deterioration of brick due to moisture is evident as
spalling, erosion, cracking, peeling paint, and
deteriorated mortar joints.
B. Some causes of brick deterioration include: a) Rising
damp, b) the accumulation of dissolved acids carried by
rainwater and condensation, c) soluble salts
crystallizing in the pores of the brick face, d)
alternate freezing and thawing, and e) the accumulation
of dirt and air-borne particles on the exterior surface.
A. Surface Preparation:
1. Wet brick having absorption rates greater than
0.025 oz. per sq. inch per minute.
a. On the flat side of a brick, deposit water on
an area approximately the size of a 25 cent
b. If the water disappears in less than 30
seconds, wet the bricks.
2. Absorptive brick should be thoroughly soaked in the
pile each afternoon prior to the day they are to be
3. Cover the bricks with tarps or heavy paper to
4. Wet brick as necessary during the day; Sprinkle the
brick pile with a hose for a period long enough for
water to run down the side of the pile; Use wetting
methods which ensure that each masonry unit is
nearly saturated but surface dry when laid; (DO NOT
wet stone masonry units).
5. Repair flashing if necessary.
6. Where fresh masonry joins existing work, clean the
exposed surface of the set masonry by removing
loose brick and mortar and wet lightly to obtain
the best possible bond with the new work.
3.03 ERECTION, INSTALLATION, APPLICATION
A. Replacing Deteriorated Masonry with Brick slips: The use
of brick slips should be limited to replacement of
individual bricks or to small areas of brickwork.
NOTE: Brick slips are brick facings about 1 inch thick.
They are used when damage to adjacent sound brickwork is
likely to occur if full-size replacement is attempted.
1. Cut out the deteriorated masonry to a regular
2. Clean the cavity of loose mortar and other debris
by hand using a chisel and stiff bristle brushes.
3. Solidly set the slip in a bed of mortar.
B. Replacing Deteriorated Units with Full-Size Bricks:
1. Carefully remove deteriorated brick units by hand
using a hammer and chisel.
2. Rebuild back-up and substrate as required to
replace any unsound material that was removed.
3. Clean the cavity of loose mortar and other debris
by hand using a chisel and stiff bristle brushes.
4. Lightly wet the exposed brick surfaces.
5. Lay brick units with completely filled bed and head
joints; Butter ends with sufficient mortar to fill
head joints and shove into place.
NOTE: Lay masonry plumb and true following the
coursing and patterns of the adjacent existing
sound construction; Level off work at required
heights and form beds to build-in salvaged or moved
6. If adjustments are required, remove units, clean
off mortar and reset in fresh mortar.
7. Blend new work into existing work smoothly with no
lines of demarcation and no change of pattern or
8. Rake all joints in replacement work to receive tuck
pointing; Joints up to 3/8" in width shall be raked
to a depth of 1/2"; Joints 3/8" in width shall be
raked to a depth of 1".
9. Brush all excess mortar from the wall surface
frequently during the work; Protect all existing
surfaces from mortar dripping and splashing.
A. Clean off adjacent surfaces which have been spattered
during the course of the work. Rinse immediately with
clean, clear water.
B. Wipe all excess mortar as the work progresses. Dry brush
at the end of each day's work.
C. After mortar is thoroughly set and cured, remove loose
mortar and dirt from new masonry surfaces.
D. Wash down the masonry surface with clean, clear water.
END OF SECTION