Renovation 4th Edition

by Michael Litchfield

  keep fiber-cement siding

  be covered. Note: Use only one nail per stud

  blocks of cedar to China to be milled into siding—

  covered. It’s cement based and

  crossing, preferably 13⁄4-in. large-head nails,

  will absorb water, even when

  one can argue that fiber cement is a viable green

  which look somewhat like roofing nails.

  preprimed. Moreover, if you

  alternative to wood siding.

  Another important detail: Leave 1⁄8-in. gaps

  install it wet, the outside will dry

  Fiber-cement clapboards come in planks

  between the butt ends of boards to allow for

  faster than the back, which could

  51⁄4 in. to 12 in. wide and from 5⁄16 in. to 5⁄8 in.

  expansion and contraction. Behind each butt

  result in paint bubbling later on.

  thick. Because FC is roughly three times the

  joint, affix a piece of flashing tape to the building

  weight of wood, 12-ft. planks are an optimal

  paper, then caulk the joint with a siliconized

  length to work with.

  acrylic caulk, which is paintable and typically

  comes with a 45-year rating.

  WORkIng WIth FC ClAPBOARDS

  Unlike wood clapboards—which are lightweight,

  SPECIAltY tOOlS

  long-fibered, and springy—fiber-cement siding is In theory, you can cut fiber-cement planks with

  heavy, short-fibered, and brittle. So although its

  hand tools and all but eliminate harmful dust.

  layout is essentially the same as that described

  But if you’re siding a whole house, a few special-

  for wood clapboards, handling fiber-cement

  ized power tools will speed the job while greatly

  planks is quite different.

  reducing the dust.

  Whenever possible, carry fiber-cement boards A circular saw with a dust-collection container

  on edge—with the width of the board perpendic-

  will ideally have a housing over the blade, with a

  ular to the ground. Boards will flex less and crack dust port at the rear that connects to a large can-

  less if carried that way. For the same reason,

  ister vacuum. Makita® has a 71⁄4-in. corded fiber-

  always have help when handling or installing

  cement saw that is among the priciest available

  long boards—it’s not a one-man job. Especially

  Exteriors

  171

  P R O T I P

  When you get fiber-cement

  siding delivered to a job site, ask

  the supplier to unload the truck

  by hand rather than rolling the

  load off, which could crack the

  clapboards. If your shipment is

  Use electric shears—also called nibblers—for cutouts in

  too large for hand-unloading, ask

  fiber cement. Cordless shears are especially helpful when

  the supplier to put a layer of

  you’re working up on scaffolding, angle-cutting boards to

  framing lumber—2x8s or

  fit under rake trim, and you don’t want to climb down to

  2x12s—under the banded bun-

  use a circular saw.

  dles to protect the siding as it

  rolls off the truck.

  Minimizing airborne silica dust is the key to working

  safely with fiber cement. Specially designed to contain

  such dust, this circular saw features a plastic cover with a

  back port that connects directly to a canister vacuum.

  Always wear a respirator and safety glasses to further

  reduce exposure.

  Once you’ve correctly set the air pressure of a pneumatic

  coil nailer, you’ll be less likely to crack brittle edges. When

  but also one of the most effective in collecting

  using a pneumatic nailer, it’s not necessary to predrill

  siding nail holes.

  dust. Of course, you should still wear a respirator

  while using it. FC circular-saw blades typically

  have four to eight polycrystalline diamond

  nibblers) don’t create much dust, some installers

  teeth, which are far more durable than carbide-

  argue that you can do without a circular saw. But

  tipped blades.

  I beg to differ: A nibbler can cut across a plank,

  Electric or pneumatic shears are another must- but a circular saw is faster and yields a cleaner

  have tool for cutting curves or inside corners in

  edge. For those not siding a whole house, the

  fiber-cement siding. Because shears (also called

  Malco TurboShear™ attachment converts most

  drill/drivers into FC shears for about half the cost

  of dedicated shears.

  A pneumatic coil nailer designed for fiber

  nibbling iN thE Air cement is a big-ticket item, but it’s worth the

  money on a whole-house job. This nailer is also a

  acircularsawproducesthecleanestcutsina

  great asset when working with fiber cement:

  fiber-cementplank.butsometimesitismore

  Once you’ve established the correct air pressure,

  convenienttouseacordlessnibbler.Forexam-

  you’re unlikely to crack this brittle siding.

  ple,ifyou’reworkingundertheeaves,notching

  Moreover, although predrilling is recommended

  aroundrafters,ormakinglong,triangularcuts

  when you’re hand-nailing FC siding, that’s not

  inraketrim,abattery-powerednibblerisper-

  necessary when pneumatic-nailing if the air pres-

  fect.Smallandportable,ittakesupnoroomon

  sure is correct and you place nails far enough

  thescaffold.Soyoucanmarkandcutboardsin

  back from the edge. Pneumatic nailers also have

  placeratherthangoingupanddownaladder,

  exposure gauges that enable you to quickly posi-

  whicheatstimeandriskscrackingFCboards.

  tion siding courses before nailing them up, much

  as roofers set shingle courses (see p. 79).

  172 Chapter 7

  Miscellaneous tools include carbide-tooth hole

  saws for dryer-vent or electrical-box cutouts and

  a carbide scoring knife or hand snips for inciden-

  tal cuts when you don’t feel like going back down

  zzzzzz Stucco Details

  Casing bead

  the ladder to get your shears. You should also have

  an N95 NIOSH-certified respirator whenever

  Lath (either wire

  you’re using power tools with FC siding.

  mesh or expanded

  metal)

  Stucco Repairs

  Two layers Grade D

  Stuccoing a whole house requires skills that take

  building paper

  years to learn, but stucco repairs are well within

  the ken of a diligent novice. If you spend a few

  hours watching a stucco job in your neighbor-

  Solid sheathing

  hood, you’ll pick up useful pointers.

  A BASIC DESCRIPtIOn

  Stucco is a cementitious mix applied in several

  layers to a wire-lath base over wood-frame con-

  struction or to a masonry surface such as brick,

  Three-coat stucco

  block, or structural tile. Like plaster, stucco is

  usually applied in three coats: (1) a base (or

  scratch) coat approximately 1⁄2 in. thick, scored

  horizontally to help the next coat adhere; (2) ar />
  brown coat about 3⁄4 in. thick; and (3) a finish

  Weep screed allows

  coat (called a dash coat by old-timers) 1⁄

  water to drip free.

  8 in. to

  1⁄4 in. thick. For repair work and masonry-

  substrate work, two-coat stucco is common.

  the mix. The mix always contains portland

  cement and sand, but it varies according to the

  amount of lime, pigment, bonders, and other

  Stucco Mixes

  agents. See “Stucco Mixes” at right, for standard

  mixes. The consistency of a mix is easy to recog-

  PoRTLandCEMEnT

  MaSonRyCEMEnT

  LiME

  Sand

  nize but hard to describe. When you cut it with a

  

  1 part

  —

  1⁄4 to 1 part

  31⁄4 to 4 parts

  shovel or a trowel, it should be stiff enough to

  retain the cut mark yet loose enough so it slumps

  

  1 part

  1 part

  —

  31⁄4 to 4 parts

  into a loose patty when dropped from a height of

  1 ft. It should never be runny.

  Building paper. Stucco is not waterproof. In

  fact, unpainted stucco will absorb moisture and

  wick it to the building paper or sheathing under-

  neath. Always assume that moisture will be pres-

  ent under stucco, and apply your building paper

  accordingly.

  Basically, you want to cover the underlying

  sheathing with two layers of building paper before

  attaching the metal lath. Two layers of Grade D

  building paper will satisfy most codes, but

  you’re better off with two layers of a fiberglass-

  reinforced paper such as Super Jumbo Tex

  60 Minute. Although 60-minute paper costs

  more, it’s far more durable. Typically, the stucco

  sticks to the first layer of paper, exposing it to

  repeated soakings until it largely disintegrates;

  the second layer is really the only water-resistant

  The perfect stucco mix is stiff enough to retain a trowel mark yet loose enough

  one, so you want it to be as durable as possible.

  to slump into a loose patty when dropped from a height of 1 ft. This mason is

  using his trowel to load stucco mix onto his hawk, which he’ll carry to the wall.

  With a trowel, he’ll apply the mix in sweeping motions.

  Exteriors

  173

  Take care not to tear the existing paper around 8-ft. sheets, is somewhat more work to install,

  the edges of a patch. Tuck the new paper under

  and costs more. Expanded metal lath is stapled

  the old at the top of the patch, overlapping old

  or nailed up; there’s no need for furring nails

  paper at the sides and bottom of the patch. If

  because it’s self-furring.

  P R O T I P

  the old paper is not intact or the shape of the

  Base coat. Here’s how to apply the base

  patch precludes an easy fit, use pieces of polymer- (scratch) coat:

  Don’t use plastic housewrap as

  reinforced flashing strips as “shingles,” slipping

  a membrane beneath stucco.

  1.Cover the sheathing with building paper and

  them up and under the existing stucco and paper

  Stucco that comes into contact

  attach the lath.

  and over the new. Caulk new paper to old at the

  with housewrap will bond to the

  edges to help keep water out.

  2.Establish screed strips, which are guides for

  surface, filling its pores and

  the stucco’s final surface thickness. Screeds can

  allowing water to pass through

  lath. Metal lath reinforces stucco so it’s less likely

  via capillary action. Stucco also

  be existing window edges, corner boards, or

  to crack and also mechanically ties the stucco

  contains surfactants (surface-

  strips manufactured for this purpose.

  to the building. Lath is a general term; it encom-

  active substances) that reduce

  passes wire mesh or stucco netting (which looks

  3.Mix and trowel on a thick first coat, press-

  the water-shedding qualities

  like chicken wire) and expanded metal lath

  ing it to the lath.

  of housewrap.

  (heavy, wavy-textured sheets). When nailing up

  4.When the mud has set somewhat, screed it

  wire mesh, use galvanized furring nails with a

  (meaning get it to a relatively uniform thickness)

  furring “button” that goes under the mesh. When using screed strips as thickness guides.

  you drive these nails in, you pinch the wire mesh

  between the nail head and the button, creating a

  5.Even out the surface further with a wood- or

  space behind the mesh into which the scratch

  rubber-surfaced float.

  coat oozes, hardens, and keys. Don’t use alumi-

  6.Press your fingertips lightly against the sur-

  num nails because cement corrodes them. Use

  face; when it is dry enough that your fingers no

  about 20 nails or staples per square yard of lath,

  longer sink in, steel-trowel the surface. Steel

  spacing nails at least every 6 in. Overlap mesh at

  troweling compacts the material, setting it well in

  least 2 in. on vertical joints, and extend it around the lath and driving out air pockets.

  corners at least 6 in.

  7.Scratch the surface horizontally.

  Expanded metal lath is a thicker, stronger lath

  used in situations requiring greater strength—for Brown coat. Installing the brown (second) coat

  example, to cover soffits, where you’re fighting

  requires the most skill, care, and time because

  gravity while applying stucco. That is, expanded

  this stage flattens the surface and builds up the

  metal lath won’t sag. It typically comes in 2-ft. by stucco to within 1⁄8 in. of its final thickness.

  Applying the brown (second) coat takes a lot of skill.

  The mason starts with an irregular scratch coat and

  builds it up until the surface is flat and within 1⁄8 in.

  of its final thickness.

  After applying the rough, brown coat with a hand trowel,

  the mason steel-trowels the surface to make the thickness

  uniform and the surface relatively flat. After the mortar

  sets, he’ll rough up the surface slightly with a wood- or

  rubber-faced float.

  174 Chapter 7

  hElPFul MAtERIAlS

  Diagnosing stuCCO The following materials are particularly useful

  PrOBlEMs

  for repair work and are available from any

  masonry supplier.

  Herearesomecommonsymptomsofstucco

   Weep screed is a metal strip nailed to the

  problemsandtheirprobablecauses.

  base of exterior walls, providing a straight

   diaGonaLCRaCkSfromthecornersofdoor

  edge to which you can screed stucco. Because

  orwindowtrimindicateashiftingfoundation;

  it is perforated, it allows moisture to “weep,”

  callastructuralengineer.

  or migrate free from the masonry surface, thus

  

  allowing it to dry thoroughly after a rain. Weep
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  CRUMbLinGSTUCCoalongthebaseofawall

  screeds are an easy way to make the bottom

  suggestsstandingwaterandprobabledeteriora-

  edge of stucco look crisp and clean. And

  tionofthesheathing.Cutbackthedamaged

  because the weight of the stucco flattens the

  areaandinstallaweepscreedsowatercanexit.

  screed down against the top of a foundation,

  P R O T I P

   LaRGEPaTCHESFaLLinGoFFsuggestfaulty

  the screed provides a positive seal against

  flashing,rottedsheathing,orlaththat’sinsuf-

  termites and other pests. (Stucco’s tendency

  two ways

  ficientlyattached. Note:ifyouseeashiny

  to reduce stucco

  to retain moisture makes rot and insect infest-

  shrinkage cracks: (1) Add nylon

  surfacebeneathasectionofstuccothatfelloff,

  ation particular problems.) Weep screed is

  fiber to the scratch coat. (2)

  theinstallerlikelywaitedtoolongtoapplythat

  also a good solution for the frequently rotted

  After the top stucco coat has

  coat,mistakenlylettingthebonderdry.inthis

  intersection of stucco walls and porch floors.

  cured at least three weeks, paint

  case,roughenthesurfacewithachiselbefore

  Weep screed isn’t difficult to retrofit, but

  it with an elastomeric paint,

  applyingnewbonderandastuccopatch.

  you’ll need to cut away the base of walls 6 in.

  which flexes as materials expand

  to 9 in. high to flash the upper edge of the

  and contract.

  screed strip properly. Cut the screed with

  aviation snips, and fasten it with large-head

  8d galvanized nails.

  

  To apply the brown coat, trowel on the stucco,

  Wire corners are preformed corners

  screed it to a relatively uniform thickness, float

  (also called corner aids) that can be fastened

  the surface further, and steel-trowel to improve

  loosely over the wire lath with 6d galvanized

  the uniformity. Then roughen the surface slightly nails. Set the corner to the finished edge,

  with a wood or rubber float. As the stucco sets

  taking care to keep the line straight and either

  up, you will be able to work it more vigorously

  plumb or level.

  to achieve an even, sanded texture that will

   Latex bonders resemble white wood glue.

  allow the finish texture coat to grab and bond.

  They are either painted into areas to be

  Do not leave the brown coat with a smooth, hard- patched or mixed into batches of stucco and