Renovation 4th Edition

by Michael Litchfield

  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.

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  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