Protecting surfaces. Spread tarps to catch mor-
tensile strength of any mortar listed here, so it best resists wind and soil movement.
tar droppings. And if you’re working on a chim-
Type N offers medium compressive strength (800 psi) and is suitable for
ney, tack plywood over the windows to protect
all above-grade uses, including those subject to heavy weathering, such as
glass from falling bricks or tools.
chimney mortar.
Cleanup. At the end of the day, clean tools well.
Type O has a low compressive strength (325 psi) and is limited to nonload-
Wet them down and use a wire brush as needed
bearing interior uses. However, it is sometimes specified for repointing chimneys
to remove hardened materials. Before lunch
with soft, old brick that would be destroyed by stronger mortar (see “The Mortar
breaks or at the end of the day, run a few shovel-
Mix” on p. 222 for more information).
fuls of gravel and a few buckets of water in the
Type K is an extremely low-strength (100 psi) mortar and is not recommended.
concrete mixer to loosen caked materials. Then
of the mortar types listed here, type n is the most versatile. a simplified version
dump it out, ensuring that the barrel wall and
of its proportions is 1 part portland cement, 1 part lime, and 6 parts sand (or 1 part
mixer blades are clean.
masonry cement and 3 parts sand). Before portland cement became widely used in
the 19th century, mortar was usually a mixture of lime and sand (animal hair was
Working with Brick
often added to reduce cracking). if brickwork 100 years old or older needs repointing,
Common brick-related repairs include repointing
use type o so it won’t destroy the brick (roughly, 1 part portland cement, 2 parts
mortar joints, repairing chimney tops, rebuilding
lime, and 4 parts fine sand).
chimneys and fireboxes, and cleaning bricks. You
may also have to repair or add flashing where the
chimney meets the roof, as shown in chapter 5.
Less common repairs include filling openings
after the removal of doors or windows. If you
want to create an opening in a brick wall, leave
that to a structural engineer and a licensed and
insured mason.
Masonry
217
To conserve resources and get the best-looking
TWo WAys To CUT BriCk
results, respect existing masonry. Match existing
bricks and mortar as closely as possible, includ-
ing the width of mortar joints. When repointing
brick, choose a mortar of appropriate strength.
Using a mason’s hammer, score all
TyPes and TerMs
the way around the brick, then strike
the scored lines sharply. Cuts will be
Of the many types of brick available, renovation
more accurate if you place the brick
calls mainly for building brick, also called com-
on a bed of sand.
mon brick. Building brick is classified according
to its weathering grade: SW (severe weathering),
MW (moderate weathering), and NW (nonweath-
ering). SW grade should be used where brick-
work will be below grade—that is, in contact
with the soil and hence subject to freezing in cold
climates. Use SW on all floors, whether indoor or
outdoor. MW grade is used indoors or on exteri-
ors above grade. NW is used only indoors,
though not as flooring.
Standard-size brick is nominally 8 in. by 4 in.
by 22⁄3 in., but it is actually 75⁄8 in. by 35⁄8 in. by
21⁄4 in. to accommodate mortar joints 3⁄8 in. thick.
Using a brick-cutting tool, slice
Thus, three courses of brick (and mortar) will be
small amounts of a brick to ensure a
approximately 8 in. high.
close fit. This tool is safer and
Brick also is named according to how it is
quieter than using a diamond blade
in a power saw.
positioned, whether it is laid on its face, end, or
side. Stretcher and header are the most common
placements, with rowlock patterns often being
used to finish courses beneath windowsills or to
cap the tops of walls where coping isn’t used.
In masonry work, the word bond has several
meanings. Mortar bond denotes the adhesion of
brick (or block) to mortar. Structural bond refers
to the joining or interlocking of individual units
to form a structural whole. If there are two
wythes (pronounced w-EYE-ths) of brick (a dou-
ble wall), the wythes may be bonded structurally
by steel ties, by header bricks mortared into both
wythes, or by grout poured into the cavity
between the two wythes. Finally, pattern bond
indicates brick placement, as shown in “Bond
Soldier
zzzzzz Brick names Based on Positioning
Patterns” on the facing page.
Rowlock
If you’re laying up a typical brick pattern—
say, running bond—you will need about
63⁄4 bricks per square foot of wall; figure 7 bricks
Header
per square foot to have enough extra for waste.
As you handle bricks, inspect each for soundness.
All should be free of crumbling and structurally
significant cracks. When struck with a trowel,
bricks should ring sharp and true.
Stretcher
218 chapter 9
Basic BrickWorking TecHniques
You should wet bricks before using them so they
won’t absorb moisture from the mortar. Hose
zzzzzz Bond Patterns
down the brick pile once a day (more often in
hot, dry weather), but don’t overdo it. If the
bricks become too wet, they will slide around on
the mortar bed.
Cutting bricks. Wear eye protection when cut-
Running
Common
ting bricks. If you’re cutting across brick faces,
rent a brick cutter, a levered tool that cuts easily.
Otherwise, cut bricks by hand.
An experienced mason can score and cut
bricks with only a trowel, but you’ll probably find
that a brick set works better. Placing the brick on
a bed of sand makes the brick less likely to jump
Roman third
Stretcher
when you strike the brick set. After marking the
cutline on the face of the brick, hold the brick set
perpendicular to the brick and strike it with a
4-lb. hand sledge. Because the edge of the brick
set is beveled on one side, keep the bevel on the
waste side of the line. You can also use a mason’s
hammer as shown in the top photo on the facing
Flemish
Dutch cross-bond
page, controlling the cut by using the hammer
point to score entirely around the brick. Then rap
the scored line sharply to break the brick.
Dry mixing. When mixing mortar, mix the ingre-
dients dry first to ensure a uniform mixture.
Once that’s done, create a pocket in the middle,
and add water gradually. As you add wate
r, be
Stacked soldier
Stacked header
fastidious about turning out the material in the
corner of the mixing pan so that there will be no
Running, common, Roman third, Flemish, and Dutch cross-bond
dry spots. Mortar should be moist yet stiff. A
are stronger because their head joints are staggered.
batch that’s too wet will produce a weak bond.
Once the mix is nearly right, its texture will
change radically if you add even a small amount
the right-hand edge of the trowel raised slightly,
of water.
take a pass through the mortar from 6:30 to
Mortar will remain usable for about 2 hours,
12:00. Make the second pass with the left-hand
so mix only about two buckets at a time. If the
side of the blade tipped up slightly, traveling from
batch seems to be drying out, “temper’ it by
5:30 to 12:00. According to master mason and
sprinkling a little water on the batch and turning
author Dick Kreh, a trowelful of mortar should
it over a few times with a trowel. As you seat
resemble “a long church steeple, not a wide
each course of bricks in mortar, use the trowel
wedge of pie.’
to scrape excess mortar from joints gently and
The second method is to hold the trowel blade
throw it back into the pan or onto the mortar-
at an angle of about 80° to the mortarboard.
board. Periodically turn that mortar back into the Separate a portion of mortar from the main pile
batch so it doesn’t dry out. Don’t reuse mortar
and, with the underside of the trowel blade, com-
that drops on the ground.
press the portion slightly, making a long, tapered
Trowel techniques. Hold a trowel with your
shape. To lift the mortar from the board, put the
thumb on top of the handle—not on the shank
trowel (blade face up) next to the mortar, with
or the blade. This position keeps your thumb out
the blade edge farthest away slightly off the
of the mortar, while giving you control. Wrap
board. With a quick twist of the wrist, scoop up
your other fingers around the handle in a
the mortar. This motion is a bit tricky: If the mor-
relaxed manner.
tar is too wet, it will slide off.
There are two basic ways to load a trowel with
To unload the mortar, twist your wrist 90° as
mortar. The first is to make two passes: Imagine
you pull the trowel toward you. This motion
that your mortar pan is the face of a clock. With
spreads, or strings, the mortar in a straight line.
Masonry
219
It is a quick motion, at once dumping and string-
ing out the mortar, and it takes practice to mas-
Mortar Types (asTM c 270-68)*
ter. If you are laying brick, practice throwing
,†
mortar along the face of a 2x4, which is about the
pOrTlaNd MaSONry hydraTed liMe
same width as a wythe of brick. Each brick
Type
ceMeNT
ceMeNT
or liMe puTTy
aggregaTe‡
course gets a bed of mortar as wide as the wythe.
After you’ve strung out the mortar, furrow it
M
1
1
—
not less than 21⁄4
lightly with the point of the trowel to spread the
and not more than
mortar evenly. Trim off the excess mortar that
1
—
1⁄4
three times the sum
hangs outside the wythe, and begin laying brick.
S
1⁄2
1
—
of the combined
laying brick. If the first course is at floor level
volumes of lime
—
>1⁄4–2
(rather than midway up a wall), snap a chalkline
and cement used
to establish a baseline. Otherwise, align new
N
—
1
—
bricks to existing courses.
1
—
>1⁄2–11⁄4
Throw and furrow a bed of mortar long
enough to seat two or three bricks. If you’re fill-
O
—
1
—
ing in an opening, “butter” the end of the first
brick to create a head joint, as shown in photo 2
1
—
>11⁄4–21⁄2
below. Press the brick into position, and trim
K
1
—
>21⁄2–4
away excess mortar that squeezes out. Both bed
and head joints are 1⁄2 in. to 5⁄8 in. thick until the
brick is pressed into place, with a goal of com-
* Adapted from the publications of the American Society for Testing and Materials, as are the compres-
pressing the joint to about 3⁄8 in. thick.
sion figures given in the text.
Use both hands as you work: One hand
† Parts by volume.
maneuvers the bricks, while the other works the
‡ Measured in a damp, loose condition.
trowel, scooping and applying mortar and tap-
ping bricks in place with the trowel handle. If
you use a stringline to align bricks, get your
FroM THE ArCHivEs: olD-sCHool BriCklAying
1. Experienced masons lay up bricks from the corners in, 2. After using a bricklayer’s trowel to throw and furrow a 3. Before the mortar is compressed, moving string guides up as they complete each course.
mortar bed, butter one end of the brick to create a head joint.
it is 1⁄2 in. to 5⁄8 in. thick, as shown.
Press the brick into the mortar to
create a good bond, compressing the
mortar to 3⁄8 in. thick.
5. After the mortar joints have set
enough to retain a thumbprint, strike
(tool) them to compress the mortar
and improve weatherability. strike
the head joints, as shown, before
striking the bed joints. (This tool is a
convex jointer.)
4. After using the end of the trowel handle to tap the
brick down, trim off the excess mortar.
220 chapter 9
thumb out of the way of the string just as you put
the brick into the mortar bed. As you place a
brick next to one already in place, let your hand
zzzzzz Throwing Mortar
rest on both bricks; this gives you a quick indica-
tion of level.
When you have laid about six bricks in a
course, check for level. Leaving the level atop the
course, use the edge of the trowel blade to tap
high bricks down—tap the bricks, not the level.
Tap as near the center of the bricks as the level
will allow. If a brick is too low because you have
scrimped on mortar, it’s best to remove it and
reapply the mortar.
Next, plumb the bricks, holding the level lightly
As you turn the trowel to unload the
against the bricks’ edges. Using the handle of the
mortar, pull it toward
you quickly, thus
trowel, tap bricks until their edges are plumb.
stringing the mortar in a line.
(Hold the level lightly against the brick, but avoid
pushing the level against the face of the brick.)
Finally, use the trowel handle to tap bricks forward
or back so that they align with a mason’s line or a
level held lightly across the face of the structure.
The last brick in a course is called the closure
zzzzzz Mortar joints
brick. Butter both ends of that brick liberally and
slide it in place. The bed of mortar also should be
generous. As you tap the brick into place with the
trowel handle, scrape excess mortar off, ensuring
Flush
a tight fit. If you scrimp on the mortar, you may
need to pull the brick out and remortar it, per-
haps disturbing bricks nearby.
Striking joints. Striking the mortar joints, also
called tooling the joints, compresses and shapes
the mortar. Typically, a mason will strike joints
every two or three courses before the mortar
Raked and tooled
“V”
dries too much. To test the mortar’s readiness for
striking, press your finger into it. If the indenta-
tion stays, it’s ready to strike. If the mortar’s not
ready for striking, wet mortar will cling to your
finger and won’t stay indented.
Use a tuck-pointing (or plugging)
Use a jointer to strike joints. First, strike the
chisel to cut back eroded mortar
head joints and then the bed joints. The shape of
before repointing joints. The tool’s
narrow blade fits easily into joints so
the joint determines how well it sheds water. As
Extruded
Struck
it is unlikely to damage brick faces.
suggested in “Mortar Joints,” joints that shed
water best include concave (the most common),
V-shaped, and weathered joints. Flush joints are
only fair at shedding water. Struck, raked, and
extruded joints shed poorly because they have
shelves on which water collects.
Concave
rePoinTing MorTar joinTs
Weathered
Even materials as durable as brick and mortar
break down in time, most commonly near the top
of a wall or chimney, where masonry is most
exposed to the elements. Often, the structure
wasn’t capped or flashed properly. If the bricks
are loose, remove them until you reach bricks
that are solidly attached. If joints are weathered
Masonry
221
Renovation 4th Edition Page 51
