Renovation 4th Edition

by Michael Litchfield

  bricks heat up, they have no room to expand, so

  they crack and spall (flake).

  Tools foR RAkInG MoRTAR

  Although mortar analysis is the best way to

  Before you can repoint joints, you must rake (cut back) old mortar, preferably without

  match old mixes—historic preservation agencies

  damaging surrounding brick. you’ve got several options:

  can suggest mortar analysts—type O mortar

  

  (described in “Mortar Types,” p. 217) should be a

  TucK-pOiNTiNg (pluggiNg) chiSelS are usually thinner than mortar joints. used

  close match for most old mortars. For this, mix

  with a 2-lb. hand sledge, they’re slow but exact.

  1 part portland cement, 2 parts hydrated lime,

   aN 18-vOlT cOrdleSS griNder with a 41⁄2-in. abrasive wheel is the tool of choice

  and 8 parts fine sand. The mix should be fairly

  if you’re topside, raking out chimney mortar. There’s no extension cord to wrestle

  stiff as mortar mixes go, keeping its shape when

  with, and the tool has plenty of power—take care not to damage soft brick. Start the

  squeezed into a ball. If the mix becomes too stiff

  abrasive wheel in the middle of a mortar joint and gradually widen the cut.

  to work, periodically sprinkle on and stir in small

   pNeuMaTic air chiSelS represent a good balance of speed and control, but you’ll

  amounts of water.

  need to special-order mortar-removal bits. Trow & holden (Barre, vt.) offers a set that

  If you’re repointing only a section of a struc-

  includes 1⁄8-in. and 1⁄4-in. cape chisels, a 1⁄4-in. swept cape chisel, and a 4-tooth ripper.

  ture, however, and don’t want it to stick out like a

  sore thumb, experiment with combinations of

  Of course, wear safety goggles and a respirator when cutting mortar.

  mortar dye, cement, sand, and lime, carefully

  labeling the proportions of each batch and allow-

  ing it to dry for a month before committing to a

  recipe. Masonry-supply houses stock such mate-

  rials; they also carry new bricks manufactured to

  but bricks remain firmly attached, repoint (or

  look old should you need to replace bricks as well.

  tuck-point) the joints by partially cutting back

  the mortar, adding new mortar, and shaping the

  Repointing technique. Using a spray bottle or a

  joints. If the brick is painted, see “Stripping

  brush, dampen the newly cleaned-out joints

  Painted Brick” on the facing page. Finally, if

  before applying fresh mortar. There are two ways

  vertical or diagonal cracks run through several

  to fill joints with new mortar. If you’re repointing

  courses, there may be underlying structural prob- a relatively small area, use a bricklayer’s trowel

  lems, which must be corrected before repointing. as a palette for the mortar and a tuck-pointing

  In this case, consult a structural engineer.

  trowel to push the mortar into the joint (see the

  bottom photo on p. 230). Press the mortar firmly

  Raking old mortar. For best results, rake out

  so that it will stick.

  (scrape out) mortar joints in an inconspicuous

  If you’re repointing a large area, use a grout

  area as a test, starting with the least destructive

  bag to squeeze the mortar into the joint. A grout

  tool. If the mortar is soft enough, an old screw-

  bag looks like the pastry bag used to dispense

  driver may be all you need. But if the mortar is as fancy icing onto cakes. You force the mortar out

  hard as the brick, you’ll need to be patient. Cut

  by twisting the canvas bag. But you’ll need strong

  joints 1 in. deep, and try to cut a square trough

  hands and forearms to twist the filled 5-lb. to

  (not a V-groove) in the old mortar.

  10-lb. bag. And you may need to thin the mix

  Once you’ve raked the joints to the correct

  slightly so it will flow easily through the bag.

  depth, brush them out well, using a whisk broom After using a grout bag, you’ll still need to tuck-

  or a wallpaperer’s brush, which you can also use

  point the mortar joints.

  to wet down the joints before adding fresh mor-

  When the mortar has dried enough to retain

  tar. Remove debris with an air hose or a heavy-

  the imprint of your thumb, tool the joints. In

  duty vacuum. Of course, wear safety glasses and

  most cases, use a jointer that creates mortar

  a respirator for this work.

  joints the same shape as the old ones. Point the

  The mortar mix. Try to match the old mortar

  head joints first, then the bed joints. As you work,

  mix when repointing an older brick building.

  use a trowel to clean the mortar from the brick

  Before portland cement was widely used, mortar

  faces, but don’t disturb the mortar joints. Then

  joints were usually a resilient mix of hydrated

  wait two to three hours before using a stiff plas-

  lime and sand, which compressed slightly as the

  tic-bristle brush to remove the mortar still stuck

  bricks expanded during summer and expanded

  to the brick faces.

  slightly as the bricks contracted during cool

  weather. Soft, lime-rich mortars also show autog-

  cleaning and sealing exTeriors

  enous healing, an ability to self-repair hairline

  Use the gentlest, least damaging cleaning agents,

  cracks caused by seasonal temperature shifts.

  chemicals, steam cleaner, or water pressure that

  Mortar joints with portland cement, on the other works. Determine this by testing in an inconspic-

  hand, are relatively hard and inflexible: As old

  uous area. If the gentlest method doesn’t work,

  222 chapter 9

  move to the next strongest. If mortar joints are

  Working MorTAr inTo JoinTs

  eroded, a pressure washer may make them leak.

  After cleaning, allow the brickwork to dry for two

  to three days, then caulk gaps around doors and

  windows and replace worn flashing. Safety note:

  Whatever cleaning method you choose, wear a

  option 1: let your bricklayer’s trowel

  serve as a palette as you scoop mortar

  face shield, rubber gloves, protective clothing,

  from it with your smaller pointing

  and a respirator.

  trowel and press mortar into joints.

  Cleaning brick surfaces. Get bids on hiring an

  Two trowels are useful when

  authorized cleaning service. Because cleaning

  repointing old joints.

  solvents can be hazardous and must be disposed

  of according to Environmental Protection Agency

  (EPA) and local environmental standards, hiring

  professionals will spare you those headaches.

  Moreover, the service will be responsible for

  achieving the desired results, however long it

  takes. If you’ve got a tight budget or an adventur-

  ous spirit, consider the DIY options described

  option 2: or you can use a grout bag

  next; they’re listed more or less in order of gentle-

  if you’ve got a lot of joints to fill. But

  ness. Wear saf
ety goggles and rubber gloves for

  this is hard work: The bag is heavy,

  all procedures, and read operating manuals care-

  and you need to twist hard to force

  the mortar out a small opening—a bit

  fully before using pressure washers, steam clean-

  like wringing water from a stone.

  ers, and the like.

  Use a garden hose to soak the surface, and

  then scrub with a nylon scrub brush. The warmer

  the water and the longer the soak, the more dirt

  you’ll remove.

  If the hose wash isn’t sufficient, try a pressure

  washer on a low setting. Increase the pressure

  slightly—say, to 300 psi to 400 psi—and you’ll

  remove yet more. Note: If you see sand in the

  Here, a bullhorn jointer compresses

  mortar joints.

  runoff water, lower the machine’s pressure set-

  tings immediately. Otherwise, you may be strip-

  ping the mortar joints. Likewise, monitor the

  inside of the building, especially around win-

  dows, for leaks; it’s easier to lower the pressure

  than to replace drywall.

  Steam cleaning is especially effective if sur-

  faces are mossy or have ivy “trails” or built-up

  grime. Although somewhat slower than pressure

  washing, steam doesn’t generate the volume of

  runoff and won’t penetrate as deeply into brick

  surfaces or cracks.

  stripping PAInTeD BRICk

  If you’re in an urban area where soot and auto

  exhaust have soiled the building, try a nonionic

  if you intend to repoint a painted brick wall, strip the paint first—no small job. For

  detergent with a medium pressure (1,000 psi)

  this, rent a pressure washer. ask the rental company to recommend a tip size and pres-

  next. Nonionic detergents such as Rhodia®’s

  sure—1,800 psi to 2,500 psi is common for stripping—and show you how to use the

  Igepal® and Dow®’s Tergitol™ and Triton™ won’t

  machine safely. Buy heavy-duty tarps, too. Caveat: removing paint by any method

  leave visible residues, as household detergents

  makes a prodigious mess.

  and trisodium phosphate (TSP) will. Again, scrub

  at the job site, test the washer on an out-of-the-way area first. if the stripped brick

  with a synthetic-bristle brush, and rinse well.

  doesn’t look so great, rethink stripping it. The brick may have been painted in an

  If these methods don’t produce the results you

  attempt to protect crumbling mortar joints and eroding brick from further weather-

  want, proprietary chemical cleaners are the next

  ing. Finally, never sandblast old brick: Sandblasting equipment will destroy brick in a

  step. They usually involve a three-step process—

  flash, and it’s dangerous to use.

  wetting surfaces, applying the cleaner and scrub-

  bing it in, and then rinsing—repeated as many

  times as needed. If you apply the cleaner, follow

  Masonry

  223

  the manufacturer’s instructions to the letter.

  siloxanes, and silane/siloxane blends. Both pre-

  P R O T I P

  Instructions will be quite specific about safety

  mixed and concentrated coatings are available—

  garb, dilution rates, dwell times (how long the

  typically applied in several coats. Some water-

  although it may seem counter-

  chemical remains on), washer settings, and tem-

  repellent coatings double as graffiti barriers,

  intuitive, start washing brick

  perature ranges (most don’t work well below

  although they tend to be shiny.

  walls at the bottom and work up,

  50°F). Before committing to a cleaning system,

  Waterproof coatings come closer to being true

  keeping the whole wall wet as

  you progress. if the entire wall is

  visit the manufacturer’s website and call its tech-

  sealers because they’re usually pigmented or

  wet, dirty water and diluted

  support number.

  opaque and form a thin elastomeric (flexible)

  cleaners running down won’t

  film. Chemically, they run the gamut from water

  Sealing exteriors. Are water-repellent or water-

  streak the cleaned sections, but

  based to bituminous. Bituminous varieties are

  proof coatings necessary on exterior masonry

  dirty water and chemicals run-

  widely applied below grade on building founda-

  walls above grade? Mostly, no. There may be a

  ning over unwetted dirty sec-

  tions and, to a lesser extent, to interior basement

  few 200-year-old buildings in every city whose

  tions will leave marks.

  walls where mild leaks have occurred.

  porous brick would benefit from being coated,

  but most masonry exteriors won’t admit water if

  rain is directed away from the structure by gut-

  Chimneys

  ters, downspouts, and other standard drainage

  Masonry chimneys are freestanding units that

  details and if the masonry is properly flashed,

  carry exhaust gases out of the house. To prevent

  caulked, and detailed.

  superheated gases from escaping, chimneys

  Exterior sealants, loosely divided into water-

  should be tile lined and free from cracks or gaps,

  repellent and waterproofing coatings, don’t fully

  or they should have insulated stainless-steel

  seal masonry surfaces, nor would you want them flues. Annual inspections and maintenance are

  to. A perfect seal could trap water inside the

  crucial to chimney health: If you discover mortar

  walls. Moreover, masonry walls with water

  or flue tiles that are cracked or missing, the

  trapped inside and walls that are wicking mois-

  chimney is unsafe. Chimney flashing and roof

  ture from the ground will, in time, exude soluble

  safety are further discussed in chapter 5.

  salts in the masonry as powdery white substances

  These days, new and retrofit chimneys are

  called efflorescence.

  often nonmasonry. There are several reasons

  Water-repellent coatings, which are typically

  for this transition: building code and insurance

  clear, penetrate masonry pores and keep rain

  requirements; a shrinking pool of qualified

  from penetrating to a large degree, while allow-

  P R O T I P

  masons; and the inherent inflexibility and

  ing water vapor from living areas to escape

  tendency of masonry to crack and compromise

  through the wall. Most water-repellent com-

  in spite of recommendations

  safety when structurally stressed. Perhaps most

  pounds are water based, formulated from silanes,

  you may get from store clerks or

  important, a host of safe, cost-effective, and

  old-time masons, don’t use muri-

  atic acid to clean masonry sur-

  faces. its fumes are noxious. it

  can burn your skin and, if you get

  openings in Brick Walls

  it in your eyes, blind you. it also

  etches the surface of stone,

  if you want
to add a door or window to a brick wall, hire a structural engineer to see if that’s feasible.

  brick, and mortar joints and

  if so, hire an experienced mason to create the opening; this is not a job for a novice. if the house was

  weakens their ability to shed

  built in the 1960s or later, the wall will likely be of brick veneer, which can be relatively fragile because

  water. and it stains.

  the metal ties attaching a brick veneer to wood- or metal-stud walls tend to corrode, especially in humid

  or coastal areas. in extreme cases, steel studs will rust, and wood studs will rot. When opening veneer

  walls, masons often get more of a challenge than they bargained for.

  Brick homes built before the 1960s are usually two wythes thick (with a cavity in between), very

  heavy, and very likely to have settled. undisturbed, these walls may be sound, but openings cut into

  them must be shored up during construction, adequately supported with steel lintels, and meticulously

  detailed and flashed. Moreover, creating a wide opening or one too close to a corner may not be structur-

  ally feasible, so a structural engineer needs to make the call.

  To close off an opening in a brick wall, remove the window or door and its casings, and then pry out

  and remove the frame. Prepare the opening by toothing it out—that is, by removing half bricks along the

  sides of the opening and filling in courses with whole bricks to disguise the old opening. The closer you

  can match the color of the existing bricks and mortar, the better you’ll hide the new section. as you lay

  up bricks, set two 6-in. corrugated metal ties in the mortar every fourth or fifth course, and nail the ties

  to the wood-frame wall behind. leave the steel lintel above the opening in place.

  224 chapter 9

  easily installed insulated metal chimneys are now

  available. That noted, the review here is limited

  about chimney Fires

  to masonry chimneys.

  The root cause of a chimney fire is the imperfectly burned material in wood

  cleaning a cHiMney

  smoke that condenses and sticks to the inside of a chimney. creosote is a sticky

  Chimneys and their flues should be inspected at

  brown or black substance that may harden to the consistency of glass. incomplete

  least once a year and cleaned as needed—ideally,

  combustion also produces tar, ammonia, methane, carbon monoxide, toluene, phe-

  before the heating season. Better chimney-

  nol, benzene, and eventually, turpentine, acetone, and methyl alcohol.

  cleaning services will get up on the roof, inspect