Renovation 4th Edition

by Michael Litchfield

  As two unseen helpers on the other

  side of this double-sided fireplace

  head sock is also a good idea because you’ll be

  empty joint-compound bucket for removal. Use

  steady the Franklin stove, the mason

  sitting in the dusty firebox during most of the

  only new firebricks to rebuild the back wall of

  tips it upright. she placed heavy sheet repairs. Finally, you’ll need a droplight that can

  the firebox, because that’s the portion that gets

  metal over the hearth and slid the

  withstand abuse.

  the most intense heat. Remove the damper, and if

  stove on its back into the fireplace.

  insTAlling An insUlATED FlUE PiPE

  . . . while the flexible lower section

  and an adjustable elbow will enable

  you to thread the pipe through a

  slightly offset chimney and still

  To keep internal temperatures constant and prevent

  connect to the woodstove outlet.

  condensation, insulate the lowest 6 ft. to 8 ft. of stainless-

  steel flue liners with heat-resistant mineral wool batts and

  metal tape. note: The flexible flue section that attaches to

  the woodstove outlet does not need to be insulated.

  Don’t try this on a windy day. The

  entire length of flue liner is

  preassembled and screwed together

  on the ground, carried aloft, and then

  lowered into the chimney . . .

  To increase directional draw and prevent rain blow-in, the

  big monsoon cap is clamped to the top of the metal flue

  liner. A steel top plate sealed to the top of the terra-cotta

  tile centers the steel flue liner in the opening and stabilizes it.

  228 chapter 9

  nIne Fixes foR SMokInG fIRePlACeS

   Open a window. New houses are often so tightly sealed and insulated that there’s

  not enough fresh air entering to replace the smoke going up the chimney, and smoke

  exits sluggishly if at all. alternatively, install an air-intake vent near the hearth.

   use dry wood. Burning wet or green wood creates a steamy, smoky fire whose low

  heat output doesn’t create enough of an updraft and promotes creosote buildup.

   clean chimneys at least once a year. cleaning also removes obstructions, such as

  nests. a screened spark arrester will also keep birds out.

   Make sure the flue is sized properly. Flues that are too large won’t send volatiles

  upward at a fast enough rate and often allow smoke to drift back into living spaces.

  although flue pipes are sized to match woodstove flue outlets (6 in. or 8 in.), sizing

  fireplace flues is trickier. in general, a fireplace flue’s cross section should be one-

  eighth to one-tenth the area of a fireplace opening.

   reduce air turbulence inside the smoke chamber above the metal damper by giv-

  ing the corbeled bricks (p. 230) on the front face a smooth parge coat. To do this,

  brush, vacuum, and wet the corbeled bricks before applying a heat-resistant mortar

  such as ahrens® chamber-Tech 2000™. (you’ll need to remove the damper for access.)

  This is a partially dismantled fireplace firebox. To the left,

   replace the chimney rain cap. clogged or poorly designed metal or masonry caps

  the firebrick sidewall is solid enough to be left in place,

  can create air turbulence and prevent a good updraft.

  although mortar joints need repointing. The back-wall

   increase the height of the chimney. a chimney should be a minimum of 3 ft.

  firebricks have already been removed, revealing the back

  above the part of the roof it passes through and a minimum of 2 ft. above any other

  of the chimney. (An intervening wall of rubble bricks also

  was removed.)

  part of the roof within 10 ft.

   rebuild the firebox with rumford proportions. count rumford was a contempo-

  it’s warped, replace it. As you remove firebricks

  rary of Ben Franklin and almost as clever; however, he bet on the British and left the

  from the back wall, you may find an intermediate

  colonies in a hurry. But not before he invented a tall, shallow firebox that doesn’t

  wall of rubble brick between the firebox and the

  smoke and radiates considerably more heat into the living space than low, deep fire-

  outer wall of the chimney. And, as likely, the rub-

  boxes. Search the internet for companies that sell prefab rumford-style fireplace

  ble bricks also will be loose, the mortar turned to

  components—or build your own.

  sand. You can save, clean, and reuse these bricks

   install a fireplace insert. charming as they are, fireplaces are an inefficient way

  when you rebuild the rubble wall.

  to heat a house. install an efficient, glass-doored stove and you can watch the flames

  Next, remove loose or damaged firebricks

  without getting burned by wasted energy costs.

  from the sidewalls and floor of the firebox. But,

  again, if the bricks are intact, it’s a judgment call.

  If repointing the joints is all that’s needed, leave

  the bricks in place. Rap bricks lightly with the

  end of your trowel handle, however, to make sure

  For firebricks, two kinds of mortar are used.

  bricks are sound. If they’re crumbling or cracked, The first type, hydraulic-setting refractory mor-

  replace them. Interestingly, firebricks on the

  tar, cures rather than dries. Once its curing time

  floor, which are protected by insulating layers of

  has elapsed—typically 48 to 72 hours—the mor-

  ash, often only need repointing. Once you’ve

  tar is impervious to water and is acid resistant.

  removed loose bricks, sweep and vacuum the

  It’s the best all-around mortar for setting fire-

  area well (rent a shop vacuum). Using a spray

  bricks and parging the fireplace throat, and it’s

  bottle, spritz all surfaces with clean water until

  the only refractory mortar type to use outside or

  they’re damp.

  to set clay tile liners.

  Select bricks and mortar. Firebricks (refractory

  The second type, air-set or air-drying, is water-

  bricks) are made of fire clay and can withstand

  soluble and when sold premixed in pails is roughly

  temperatures up to 2,000°F. They’re bigger and

  the consistency of joint compound. Once it has

  softer than conventional facing bricks and less

  dried, however, it is durable and can withstand

  likely to expand and contract and hence are less

  high temperatures without degrading. Typically,

  likely to crack from heat. Yet, because they are

  air-set refractory mortars set more quickly, so if

  soft, they can be damaged when logs are thrown

  you’re new to bricklaying, a hydraulic-setting

  against them. Firebrick walls need tight joints of

  mortar will be more forgiving. On the other

  1⁄16 in. to 1⁄8 in. thick and thus require exact fits.

  hand, some masons report that because air-set

  To achieve this, rent a lever-operated brick cutter.

  mortars are water-soluble until they dry, you

  Masonry

  229

  Here, the mason is building a rubble-brick wall between

  Traditi
onally, the back walls of fireboxes start tilting

  gently use a mason’s hammer to seat

  the firebox and the back wall of the chimney. Firebrick

  forward at the third or fourth course to reflect heat into

  firebricks in the mortar. At this point,

  mortar joints are thin, typically 1⁄16 in. to 1⁄8 in. thick,

  the room. To create this tilt, make the mortar bed thicker

  the back wall’s forward tilt is similar

  because the firebricks do virtually all of the insulating.

  at the back, canting the course of bricks forward.

  to that of the sidewall, shown on

  Periodically, scrape off excess mortar.

  p. 229. Angle-cut firebrick to fill any

  voids between the sidewalls and the

  back wall. (A rented brick cutter is

  ideal for this.)

  don’t need to be as fastidious applying mortar—

  you can wet-sponge the firebox later to clean up

  errant mortar. (I’d be careful about diluting the

  new mortar, though.)

  Build up. The rest is basic bricklaying technique.

  String a bed of mortar as wide as the edge of a

  firebrick across the back of the firebox and press

  the brick(s) firmly into it, working from one side

  to the other. Bricks should be damp but not wet.

  Butter the ends of each brick to create head

  joints, and when you’ve laid the first course,

  check for level. Use the handle of your trowel or

  After cutting back deteriorated

  mason’s hammer to tap down bricks that are

  mortar joints, pack them with fresh

  high. Typically, you’ll need to cut brick pieces on

  mortar. Fill a margin trowel with

  each side of the back wall to “tooth into” the stag-

  refractory mortar, as shown. Then use

  zzzzzz Traditional Fireplace

  cross section

  a thin tuck-pointing trowel to scrape

  gered brick joints on the sidewalls, but that step

  mortar from it into the joint.

  Parge

  can wait until the back wall is complete. As you

  refractory cement is so sticky that it

  corbeled

  lay up each course of firebrick, lay up the rubble

  bricks to

  will cling to the margin trowel’s blade

  brick courses, which needn’t be perfect, nor do

  reduce

  even if held vertically.

  turbulence.

  you need to point their joints.

  Flue

  Unless yours is a tall, shallow Rumford fire-

  place, firebricks in the back wall should start tilt-

  Hinged

  ing forward by the third or fourth course. To do

  damper

  that, apply the mortar bed thicker at the back.

  Build up the firebox and rubble-brick walls until

  Smoke shelf

  (mortar)

  you reach the throat opening. Then fill in any

  space between the firebox and rubble-brick walls

  Throat

  Rubble brick

  with mortar, creating a smoke shelf. The smoke

  and fill

  shelf can be flat or slightly cupped.

  Once the back wall is up, fit piece bricks

  Firebricks

  Back wall

  where the back wall meets sidewalls. Clean and

  line firebox.

  of chimney

  repoint the mortar joints as needed. With a mar-

  gin trowel serving as your mortar palette, use a

  tuck-pointing trowel to “cut” a small sliver of

  mortar and pack it into the brick joints. Allow the

  mortar to dry for a month before building a fire.

  Make the first few fires small.

  230 chapter 9

  dressing up a concrete Wall

  if you’re bored with the drab band of foundation concrete around

  How traditional or free-form you make the facade depends on your

  the bottom of your house, dress it up with a glued-on brick or stone

  building’s style and your sense of fun. The clinker brick, tile, and

  facade. a number of adhesive materials will work well.

  stone facade shown completed on p. 214 nicely complemented the

  in the project shown here, the mason used sgM Marble set, intended eclectic style of the craftsman house. it would probably also look for marble or heavy tiles, but epoxies would work, too. Whatever adhe-good on the foundation of a rambling brown shingle, a gothic revival

  sive you choose, check the manufacturer’s instructions for its suitability

  house, or a more whimsical sort of Victorian.

  for exterior use in your area, especially if you have freezing winters.

  not relying on mortar joints to support the courses gives you a cer-

  use exterior-grade bricks.

  tain freedom in design, but it’s stil important that you pack joints with

  mortar and compress them with a striking tool so they shed water—

  especial y if winter temperatures in your region drop below freezing.

  Today’s masonry adhesives are so strong that they can adhere

  heavy materials—such as brick, stone, and tile—directly to

  concrete. Freed from needing to support much of anything,

  mortar joints can be as expressive as you like.

  Butter the backs of masonry elements with adhesive, in this case,

  Use short sticks to space bricks, stones, and tiles. This

  a mortar designed to adhere marble and heavy tile to concrete.

  prevents any slippage before the adhesive sets and

  creates a joint wide enough to pack mortar into.

  Compress and shape the mortar to make it adhere and

  keep the weather out.

  Masonry

  231

  Foundations

  10 and Concrete

  Foundation issues can be complex.

  An Overview

  Before starting extensive remedial work, such as

  A foundation is a mediator between the loads of

  replacing failed foundation sections or adding

  the house and the soil on which it rests. A well-

  a second story to your house, ask a structural

  designed foundation keeps a house’s wood under-

  engineer to evaluate your foundation. In addi-

  pinning above the soil so it doesn’t rot or get

  tion, bring in a soils engineer if the site slopes

  eaten by insects. And it should be sturdy enough

  steeply or if the foundation shows any of the fol-

  to keep walls plumb and floors level despite

  lowing distress signs: bowing, widespread crack-

  wind, water, soil movement, and earthquakes.

  ing, uneven settlement, or chronic wetness.

  Engineers also can assess potential concerns

  Foundation types

  such as slide zones, soil load-bearing capacity,

  Foundations should be appropriate to the site.

  and seasonal shifting.

  For example, on sandy well-drained soil,

  These concrete forms are half

  complete, showing oiled inside

  formboards, a new mudsill nailed up,

  and the bottom outer formboard in

  place. Rebar, as shown, will be wire-

  tied to anchor bolts after they’ve

  been inserted into predrilled holes in

  the mudsill.

  232

  unmortared stone foundations can last for centu-

  ries. But an unstable clay hillside may dictate an

  engineered
foundation on piers extending down

  to bedrock.

  zzzzzz Foundation types

  The tee, or spread, foundation is perhaps the

  most commonly used type, so named because its

  cross section looks like an inverted T. It’s remark-

  ably adaptable. On a flat site in temperate regions,

  a shallow tee foundation is usually enough to

  support a house, while creating a crawlspace that

  allows joist access and ventilation.

  SLAB ON

  TEE (SPREAD)

  GRADE

  Where the ground freezes, foundation footings

  FOUNDATION

  need to be dug below the frost line, stipulated by

  local codes. Below the frost line, footings aren’t

  susceptible to the potentially tremendous lifting

  and sinking forces of freeze–thaw cycles in moist

  soil. (Thus, most houses in cold climates often

  have full basements.)

  GRADE

  When tee foundations fail, it’s often because

  BEAM

  they’re unreinforced or have too small or too

  Concrete

  shallow a footprint. Unreinforced tee founda-

  pier

  tions that have failed are best removed and

  replaced. But reinforced tees that are sound can

  DRIVEN STEEL

  be underpinned by excavating and pouring larger

  WITH PAD

  footings underneath a section at a time.

  Slab on grade is a giant pad of reinforced con-

  crete, poured simultaneously with a slightly

  thicker perimeter footing that increases its load-

  Bedrock

  bearing capabilities. Beneath the slab, there’s typ-

  ically a layer of crushed gravel and sheet plastic

  over that to prevent moisture from wicking up

  from the soil. Slabs are generally installed on flat

  INTERIOR

  lots where the ground doesn’t freeze because,

  FOUNDATION

  being above frost line, shallow slabs are vulnera-

  ELEMENTS

  ble to frost heaves. Although shallow, the large

  footprint of a slab sometimes makes it the only

  Girder

  feasible foundation on soils with weak load-bear-

  ing capacity. Because slabs sit on grade, their

  drainage systems must be meticulously detailed.

  Post (column)

  Grade beams with drilled concrete piers are

  the premier foundation for most situations that

  don’t require basements. These foundations get

  Soil conditions and intended

  their name because pier holes are typically