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Fire retardant coatings : an evaluation of fire retardant coatings as a means of protecting wood panels Goldsmith, Fraser Perry 2011

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    Fire	
  Retardant	
  Coatings	
   	
   	
   An	
  evaluation	
  of	
  fire	
  retardant	
  coatings	
  as	
  a	
  means	
  of	
  protecting	
  wood	
   panels	
   	
    	
    	
    	
   	
   Fraser	
  Perry	
  Goldsmith	
   	
   	
   	
   	
   	
   	
   	
   April	
  17,	
  2011	
   	
   WOOD	
  493	
    	
   	
   	
   	
   	
   	
   	
   	
   	
   	
    Executive	
  Summary	
   The	
  protection	
  of	
  residential	
  buildings	
  from	
  the	
  effects	
  of	
  fire	
  is	
  becoming	
  increasingly	
  important.	
  For	
   example,	
  Alberta	
  has	
  altered	
  its	
  fire	
  codes	
  to	
  make	
  fire	
  protection	
  of	
  wood	
  sheathing,	
  including	
  plywood	
   and	
  OSB,	
  compulsory	
  in	
  the	
  design	
  of	
  residential	
  buildings	
  in	
  close	
  proximity	
  to	
  each	
  other.	
  Two	
  of	
  the	
   approved	
  methods	
  of	
  protection	
  are	
  through	
  the	
  use	
  of	
  fire	
  retardant	
  coatings	
  or	
  sheathing	
  the	
  OSB	
  or	
   plywood	
  with	
  exterior	
  gypsum	
  panels.	
  There	
  are	
  divided	
  opinions	
  on	
  which	
  method	
  of	
  fire	
  protection	
  is	
   superior	
  in	
  terms	
  of	
  performance,	
  convenience,	
  and	
  cost	
  effectiveness.	
  In	
  this	
  essay	
  I	
  conclude	
  that	
  fire	
   retardant	
  coatings,	
  when	
  properly	
  applied,	
  perform	
  well	
  and	
  are	
  a	
  convenient	
  method	
  for	
  protecting	
   wood	
  sheathing	
  from	
  fire.	
  However,	
  their	
  poor	
  resistance	
  to	
  weathering	
  and	
  increased	
  cost	
  make	
  them	
   a	
  less	
  cost	
  effective	
  solution	
  than	
  durable	
  gypsum	
  sheathing	
  systems.	
  Coating	
  systems	
  may	
  be	
  effective	
   when	
  used	
  to	
  compliment	
  a	
  gypsum	
  sheathing	
  system	
  to	
  protect	
  areas	
  of	
  buildings	
  that	
  are	
  difficult	
  to	
   sheath.	
  	
   	
   	
   	
   	
   	
   	
   	
   List	
  of	
  Key	
  words:	
  Intumescent,	
  oriented	
  strand	
  board,	
  Alberta	
  Fire	
  code,	
  gypsum	
  sheathing,	
  pressure	
   treatment,	
  flame	
  spread	
  rating,	
  smoke	
  developed	
  index,	
  flame	
  retardant,	
  exposure,	
  leaching,	
  weather	
   resistance,	
  wear	
  resistance.	
   	
   	
   	
   	
   	
    i	
    Table	
  of	
  Contents	
   List	
  of	
  Tables	
  and	
  Figures................................................................................................................. iii	
   1.0	
  Introduction.....................................................................................................................................1	
   1.1	
  Fire	
  in	
  Buildings .........................................................................................................................1	
   1.2	
  Flame	
  Spread	
  Rating .................................................................................................................2	
   2.0	
  Advantages	
  of	
  Fire	
  Retardant	
  Coatings ..................................................................................3	
   2.1	
  Performance	
  Characteristics..................................................................................................3	
   2.2	
  Convenience	
  of	
  Coatings ..........................................................................................................5	
   3.0	
  Disadvantages	
  of	
  Fire	
  Retardant	
  Coatings ............................................................................5	
   3.1	
  Exposure	
  Problems ...................................................................................................................5	
   3.2	
  Application	
  Issues......................................................................................................................6	
   3.2	
  Cost	
  of	
  Coating	
  Systems............................................................................................................7	
   4.0	
  Comparison	
  of	
  Coatings	
  to	
  Other	
  Systems.............................................................................9	
   4.1	
  Coating	
  Versus	
  Treatment ......................................................................................................9	
   4.2	
  Coatings	
  Versus	
  Gypsum	
  Sheathing .....................................................................................9	
   5.0	
  Conclusion	
  and	
  Recommendations....................................................................................... 12	
   6.0	
  References ..................................................................................................................................... 14	
   	
   	
   	
   	
   	
   	
   	
   	
    	
    ii	
    List	
  of	
  Tables	
  and	
  Figures	
   Figures	
   Figure	
  1	
  -­‐	
  Estimated	
  Costs	
  of	
  Coating	
  a	
  4’	
  x	
  8’	
  OSB	
  Panel……………………………………………………………8	
   (Ceasefire	
  Technologies,	
  2011)	
   Tables	
   Table	
  1	
  -­‐	
  Flame	
  Spread	
  Ratings	
  of	
  Building	
  Materials…………………………………………………………………2	
   (Williamson,	
  2002)	
   Table	
  2	
  -­‐	
  FSR	
  and	
  FDI	
  for	
  Coated	
  Wood	
  Building	
  Materials.……………………………………………………….4	
   (Quantum	
  Chemical,	
  2011)	
   Table	
  3	
  -­‐	
  Cost	
  of	
  Coating	
  System	
  Compared	
  to	
  a	
  Gypsum	
  System……………………………………………11	
   (Ceasefire	
  Technologies,	
  2011,	
  ToolBase,	
  2003)	
   Table	
  4	
  -­‐	
  Costs	
  of	
  Using	
  Fire	
  Retardant	
  Systems	
  to	
  Protect	
  a	
  House…………………………………………11	
   (Building	
  a	
  Home	
  Info,	
  2010)	
   	
   	
   	
   	
   	
   	
   	
   	
   	
    	
    iii	
    1.0	
  Introduction	
   1.1	
  Fire	
  in	
  Buildings	
   Residential	
  fires	
  have	
  always	
  been	
  a	
  cause	
  for	
  concern	
  for	
  designers,	
  specifiers	
  and	
  the	
  general	
   public.	
  The	
  destructive	
  force	
  of	
  fires	
  in	
  residential	
  buildings	
  results	
  in	
  serious	
  injuries,	
  death,	
   and	
  the	
  loss	
  of	
  millions	
  of	
  dollars	
  worth	
  of	
  property.	
  The	
  choice	
  of	
  materials	
  that	
  are	
  used	
  in	
   buildings	
  can	
  have	
  a	
  large	
  impact	
  on	
  their	
  susceptibility	
  to	
  fire	
  and	
  the	
  rate	
  at	
  which	
  the	
  fire	
  is	
   spreads	
  through	
  the	
  structure.	
  Wood	
  and	
  wood	
  composites	
  are	
  combustible	
  materials	
  and	
  will	
   naturally	
  support	
  a	
  flame.	
  Hence,	
  fire	
  is	
  able	
  to	
  spread	
  across	
  the	
  surface	
  of	
  wood	
  and	
  affect	
   areas	
  and	
  structures	
  beyond	
  the	
  origin	
  of	
  the	
  fire.	
  The	
  flame	
  spread	
  over	
  structural	
  wood	
   panels	
  such	
  as	
  plywood	
  and	
  oriented	
  strand	
  board	
  (OSB)	
  is	
  of	
  particular	
  concern	
  to	
  end-­‐users.	
  	
   Many	
  different	
  systems	
  have	
  been	
  used	
  to	
  reduce	
  the	
  combustibility	
  of	
  wood.	
  For	
  example,	
  in	
   the	
  past,	
  lumber	
  and	
  plywood	
  boards	
  were	
  pressure	
  treated	
  with	
  fire-­‐retardant	
  chemicals	
  to	
   reduce	
  their	
  combustibility.	
  Fire-­‐retardant	
  treatments	
  are	
  applied	
  in	
  basically	
  the	
  same	
  way	
  as	
   preservative	
  treatments	
  (CWC,	
  2000).	
  More	
  recently,	
  intumescent1	
  fire-­‐retardant	
  coatings	
  have	
   been	
  developed	
  to	
  protect	
  wood	
  and	
  to	
  slow	
  the	
  spread	
  of	
  flames.	
  	
   Specific	
  guidelines	
  for	
  the	
  use	
  of	
  fire	
  retardant	
  coatings	
  have	
  been	
  developed	
  to	
  minimize	
  the	
   impact	
  of	
  fires.	
  Alberta,	
  in	
  particular,	
  has	
  taken	
  steps	
  to	
  minimize	
  the	
  damage	
  and	
  area	
  affected	
   by	
  residential	
  fires	
  by	
  introducing	
  strict	
  rules	
  in	
  their	
  fire	
  and	
  building	
  codes.	
  The	
  need	
  for	
   increased	
  fire	
  protection	
  can	
  be	
  attributed	
  to	
  the	
  occurrence	
  of	
  6300	
  fires	
  each	
  year,	
  which	
  kill	
   around	
  35	
  people	
  and	
  cost	
  approximately	
  $190	
  million	
  in	
  property	
  losses	
  in	
  Alberta	
  (HIRF,	
   2008).	
  In	
  May	
  of	
  2009,	
  the	
  Alberta	
  Fire	
  Code	
  (AFC)	
  was	
  altered	
  with	
  the	
  intent	
  of	
  minimizing	
  the	
   impact	
  of	
  residential	
  fires	
  (Markusoff,	
  2009).	
  One	
  of	
  the	
  main	
  objectives	
  of	
  the	
  fire	
  codes	
  is	
  to	
   minimize	
  the	
  spread	
  of	
  fire	
  and	
  to	
  protect	
  adjacent	
  buildings	
  if	
  fire	
  does	
  occur.	
  If	
  buildings	
  are	
   within	
  certain	
  proximity	
  of	
  each	
  other	
  then	
  the	
  structural	
  wood	
  panels	
  must	
  be	
  protected	
  from	
   fire	
  by	
  an	
  approved	
  fire	
  retardant	
  system.	
  	
   	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
   1  	
    	
  A	
  substance	
  that	
  swells	
  with	
  exposure	
  to	
  heat	
  (Price,	
  2001).	
    1	
    	
  The	
  Alberta	
  Fire	
  Code	
  states	
  that	
  the	
  allowable	
  methods	
  of	
  fire	
  protection	
  are	
  fire	
  retardant	
   coatings	
  and	
  fireproof	
  gypsum	
  sheathing.	
  These	
  methods	
  of	
  protection	
  must	
  be	
  applied	
  when	
   the	
  construction	
  of	
  the	
  building	
  exceeds	
  exterior	
  grade	
  level2	
  (FPB,	
  2010).	
  There	
  is	
  no	
   consensus	
  as	
  to	
  which	
  fire	
  retardant	
  system	
  is	
  the	
  most	
  suitable	
  for	
  use	
  in	
  Alberta	
  or	
  in	
  other	
   areas.	
  To	
  adhere	
  to	
  the	
  new	
  fire	
  codes	
  builders	
  in	
  Edmonton	
  are	
  choosing	
  to	
  use	
  fire	
  retardant	
   coatings	
  whereas	
  builders	
  in	
  Calgary	
  are	
  using	
  fireproof	
  gypsum	
  sheathing	
  (Gratton,	
  2010).	
  The	
   benefits	
  and	
  potential	
  drawbacks	
  of	
  using	
  fire	
  retardant	
  wood	
  coatings	
  will	
  be	
  discussed	
  in	
  this	
   essay	
  and	
  a	
  balanced	
  conclusion	
  will	
  be	
  reached	
  as	
  to	
  whether	
  fire	
  retardant	
  coatings	
  are	
  an	
   effective	
  system	
  for	
  protecting	
  residential	
  buildings	
  from	
  fire.	
  	
   1.2	
  Flame	
  Spread	
  Rating	
   Coatings	
  used	
  to	
  protect	
  wood	
  panels	
  must	
  be	
  approved	
  by	
  the	
  Underwriter’s	
  Laboratories	
  of	
   Canada	
  (ULC)	
  with	
  a	
  class	
  “A”	
  flame	
  spread	
  rating	
  and	
  be	
  applied	
  by	
  a	
  certified	
  professional.	
   Flame	
  spread	
  rating	
  (FSR)	
  refers	
  to	
  the	
  rate	
  at	
  which	
  fire	
  is	
  able	
  to	
  travel	
  along	
  a	
  building	
   material’s	
  surface.	
  	
  The	
  FSRs	
  of	
  a	
  few	
  building	
  materials	
  and	
  the	
  relationship	
  between	
  the	
  FSR	
   and	
  the	
  flame	
  spread	
  classification	
  of	
  materials	
  are	
  illustrated	
  in	
  Table	
  1.	
   Table	
  1:	
  Flame	
  Spread	
  Ratings	
  of	
  Building	
  Materials	
  (Williamson,	
  2002)	
    Material	
   Gypsum	
  Sheathing	
   Red	
  Oak	
  Lumber	
    Flame	
  Spread	
  Rating*	
   0	
   100	
    Douglas	
  fir	
    70-­‐100	
    Structural	
  Wood	
  panels	
    76-­‐200	
    *Class	
  A	
  =	
  0	
  –	
  25	
   	
  	
  Class	
  B	
  =	
  26	
  –	
  75	
   	
  	
  Class	
  C	
  =	
  76	
  –	
  200	
    	
   	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
   2  	
    	
  Any	
  construction	
  above	
  the	
  foundation	
  of	
  a	
  building	
  (Gratton,	
  2010).	
    2	
    FSR	
  is	
  a	
  measure	
  of	
  the	
  area	
  that	
  a	
  flame	
  is	
  able	
  to	
  spread	
  over	
  during	
  a	
  defined	
  period	
  of	
  time.	
   The	
  FSR	
  of	
  building	
  materials	
  is	
  calculated	
  in	
  the	
  lab	
  by	
  exposing	
  a	
  test	
  piece	
  to	
  a	
  gas	
  flame	
  at	
   one	
  end	
  and	
  measuring	
  the	
  area	
  that	
  the	
  flame	
  spreads	
  over.	
  The	
  area	
  of	
  flame	
  spread	
  for	
  the	
   test	
  material	
  is	
  then	
  divided	
  by	
  the	
  area	
  of	
  a	
  standard	
  material	
  and	
  then	
  multiplied	
  by	
  100.	
  Red	
   oak	
  is,	
  in	
  most	
  cases,	
  the	
  standard	
  material	
  that	
  test	
  materials	
  are	
  compared	
  to.	
    2.0	
  Advantages	
  of	
  Fire	
  Retardant	
  Coatings	
   2.1	
  Performance	
  Characteristics	
   Fire	
  retardant	
  coatings	
  are	
  good	
  at	
  improving	
  the	
  performance	
  of	
  structural	
  wood	
  panels.	
  First	
   of	
  all,	
  they	
  slow	
  down	
  the	
  spread	
  of	
  fire.	
  When	
  intumescent	
  coatings	
  are	
  exposed	
  to	
  high	
   temperatures,	
  the	
  coating	
  expands	
  and	
  insulates	
  the	
  material	
  with	
  a	
  layer	
  of	
  char3.	
  In	
  this	
   process,	
  the	
  coating	
  can	
  expand	
  from	
  anywhere	
  from	
  50	
  to	
  200	
  times	
  its	
  original	
  thickness	
   (Pryzbylak	
  &	
  Kozlowski,	
  1999).	
  This	
  thick	
  char	
  layer	
  is	
  able	
  to	
  perfectly	
  insulate	
  the	
  substrate	
   below	
  and	
  greatly	
  decrease	
  the	
  rate	
  at	
  which	
  the	
  fire	
  spreads	
  across	
  the	
  surface.	
  Even	
  when	
   fire	
  temperatures	
  exceed	
  800⁰C	
  in	
  extremely	
  intense	
  fires,	
  the	
  insulating	
  layer	
  will	
  remain	
  for	
   about	
  an	
  hour	
  (Fire	
  Retardants	
  Inc,	
  2010).	
  Hence	
  the	
  structural	
  integrity	
  of	
  the	
  wood	
  is	
   maintained	
  allowing	
  people	
  more	
  time	
  to	
  evacuate	
  the	
  building	
  and	
  for	
  authorities	
  to	
  try	
  to	
   control	
  the	
  blaze.	
  	
   Most	
  commercially	
  available	
  fire	
  retardant	
  coatings	
  are	
  able	
  to	
  achieve	
  a	
  flame	
  spread	
  index	
  of	
   less	
  than	
  25	
  or	
  an	
  “A”	
  classification	
  when	
  applied	
  to	
  plywood	
  and	
  OSB.	
  SafeCoat®,	
  one	
  of	
  the	
   leaders	
  in	
  the	
  fire	
  retardant	
  coating	
  industry,	
  manufactures	
  a	
  latex	
  intumescent	
  coating	
  that	
  is	
   able	
  to	
  get	
  a	
  flame	
  spread	
  rating	
  of	
  10	
  when	
  applied	
  to	
  OSB	
  (Quantum	
  Chemical,	
  2011).	
  This	
  is	
   well	
  within	
  the	
  range	
  of	
  a	
  class	
  A	
  fire	
  retardant.	
  The	
  FSR	
  of	
  SafeCoat	
  latex	
  intumescent	
  coating	
   on	
  different	
  wood	
  substrates	
  is	
  shown	
  in	
  Table	
  2.	
    	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
   3  	
    	
  The	
  solid	
  material	
  left	
  over	
  after	
  the	
  initial	
  stage	
  of	
  combustion	
  (Pryzbylak	
  &	
  Kozlowski,	
  1999).	
    3	
    Table	
  2:	
  FSR	
  and	
  FDI	
  for	
  Coated	
  Wood	
  Building	
  Materials	
  (Quantum	
  Chemical,	
  2011)	
    Material	
    Coating	
    FSR	
    SDI4	
    Douglas	
  fir	
   lumber	
    Single	
  coat	
    5	
    0	
    SPF	
  Plywood	
    Single	
  coat	
  and	
  top	
   coat	
    5	
    0	
    OSB	
  (11mm)	
    Single	
  coat	
    10	
    20	
    	
   Many	
  fire	
  retardant	
  coatings	
  also	
  have	
  the	
  ability	
  to	
  suppress	
  the	
  production	
  of	
  gases	
  by	
  wood	
   when	
  it	
  combusts.	
  The	
  gases	
  that	
  are	
  produced	
  during	
  the	
  combustion	
  of	
  wood	
  and	
  especially	
   wood-­‐composites	
  can	
  be	
  extremely	
  dangerous.	
  Approximately	
  70%	
  of	
  deaths	
  in	
  residential	
  fires	
   are	
  attributed	
  to	
  gas	
  inhalation	
  (Markusoff,	
  2009).	
  	
   Suppressing	
  gases	
  is	
  also	
  important	
  for	
  reducing	
  flash	
  over.	
  Toxic	
  gases	
  and	
  superheated	
  air	
  can	
   reach	
  a	
  critical	
  point	
  during	
  a	
  fire	
  causing	
  the	
  gas	
  mixture	
  ignite	
  resulting	
  in	
  an	
  explosion	
  called	
   flashover	
  (Garrison,	
  2002).	
  Flashover	
  is	
  a	
  dangerous	
  time	
  in	
  house	
  fires	
  and	
  it	
  is	
  also	
  a	
   mechanism	
  that	
  enables	
  the	
  fire	
  to	
  spread	
  at	
  an	
  increased	
  rate.	
  Fire	
  retardant	
  coatings	
  also	
   decrease	
  smoke	
  development	
  which	
  delays	
  the	
  build-­‐up	
  of	
  toxic	
  gases	
  and	
  thus	
  helps	
  reduce	
  or	
   at	
  least	
  delay	
  flashover.	
  Smoke	
  development	
  index	
  (SDI)	
  is	
  used	
  to	
  quantify	
  the	
  amount	
  of	
   gases	
  that	
  are	
  released	
  when	
  a	
  building	
  material	
  is	
  exposed	
  to	
  fire.	
  Wood	
  panels	
  have	
  an	
  SDI	
   anywhere	
  from	
  25-­‐270,	
  but	
  when	
  coated	
  with	
  an	
  intumescent	
  coating	
  the	
  SDI	
  can	
  be	
  reduced	
   to	
  20	
  (Quantum	
  Chemical,	
  2011).	
  The	
  SDI	
  scale	
  is	
  similar	
  to	
  that	
  of	
  FSR	
  with	
  solid	
  red	
  oak	
  having	
   a	
  value	
  of	
  100	
  (Williamson,	
  2002).	
  	
   	
   	
   	
   	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
   4  	
    	
  SDI	
  is	
  a	
  measure	
  of	
  the	
  concentration	
  of	
  smoke	
  a	
  material	
  emits	
  as	
  it	
  burns	
  (Williamson,	
  2002).	
  	
    4	
    2.2	
  Convenience	
  of	
  Coatings	
   Fire	
  retardant	
  coatings	
  are	
  also	
  convenient	
  to	
  use.	
  Fire	
  retardant	
  coatings	
  can	
  be	
  applied	
  in	
  the	
   factory,	
  on	
  the	
  jobsite,	
  or	
  on	
  panels	
  that	
  are	
  already	
  in	
  use	
  unlike	
  fire	
  retardant	
  pressure	
   treatments.	
  Coatings	
  can	
  be	
  applied	
  using	
  the	
  same	
  methods	
  as	
  most	
  paints;	
  using	
  a	
  sprayer,	
   roller	
  or	
  brush	
  (CWC,	
  2000).	
  	
   Fire	
  retardant	
  coatings	
  can	
  be	
  added	
  to	
  existing	
  buildings	
  to	
  upgrade	
  the	
  fire	
  retardant	
   properties	
  of	
  panels	
  to	
  comply	
  with	
  modern	
  codes	
  and	
  regulations.	
  Having	
  the	
  ability	
  to	
  apply	
   the	
  fire	
  retardant	
  coatings	
  in	
  the	
  field	
  allows	
  end	
  users	
  to	
  coat	
  highly	
  customized	
  projects.	
   Hence,	
  fire	
  retardant	
  coatings	
  can	
  be	
  applied	
  to	
  key	
  areas	
  of	
  importance	
  instead	
  of	
  being	
   applied	
  to	
  full	
  sheets	
  of	
  fire	
  sheathing.	
  The	
  AFC	
  does	
  not	
  state	
  that	
  all	
  of	
  the	
  structural	
  wood	
   panels	
  have	
  to	
  be	
  fully	
  coated.	
  Instead	
  only	
  the	
  inside	
  face	
  of	
  the	
  wood	
  panels	
  and	
  the	
  outer	
   rim	
  of	
  the	
  wood-­‐flooring	
  panels	
  must	
  be	
  coated.	
  So,	
  by	
  applying	
  the	
  coatings	
  in	
  the	
  field,	
  the	
   fire	
  retardant	
  is	
  only	
  applied	
  to	
  those	
  areas	
  which	
  need	
  it	
  most	
  and	
  thus	
  minimizing	
  the	
  amount	
   of	
  fire	
  retardant	
  materials	
  that	
  are	
  required.	
  	
    3.0	
  Disadvantages	
  of	
  Fire	
  Retardant	
  Coatings	
   3.1	
  Exposure	
  Problems	
   There	
  are	
  some	
  issues	
  which	
  make	
  fire	
  retardant	
  coatings	
  them	
  less	
  suitable	
  for	
  their	
  purpose.	
   First	
  of	
  all,	
  not	
  all	
  fire	
  retardant	
  coatings	
  can	
  be	
  used	
  outdoors	
  without	
  losing	
  their	
  fire	
   retarding	
  capabilities.	
  Fire	
  retardant	
  chemicals	
  can	
  leach	
  from	
  the	
  underlying	
  wood	
  substrate	
   when	
  exposed	
  to	
  high	
  humidity	
  or	
  rain,	
  rendering	
  the	
  materials	
  unprotected	
  from	
  fire	
  (CWC,	
   2000).	
  Some	
  coatings	
  are	
  “exterior	
  rated”	
  and	
  can	
  stand	
  up	
  to	
  the	
  elements,	
  however,	
  these	
   are	
  typically	
  more	
  expensive.	
  Other	
  coatings,	
  such	
  as	
  SafeCoat	
  latex	
  intumescent	
  coating,	
  can	
   have	
  a	
  water	
  resistant	
  coating	
  applied	
  on	
  top	
  of	
  them	
  to	
  make	
  them	
  suitable	
  for	
  use	
  outdoors	
   (Quantum	
  Chemical,	
  2011).	
   In	
  most	
  cases	
  the	
  wood	
  sheathing	
  will	
  not	
  be	
  exposed	
  to	
  the	
  elements	
  in	
  its	
  final	
  application.	
   Siding	
  material	
  made	
  from	
  wood,	
  composite,	
  or	
  plastic	
  will	
  most	
  likely	
  be	
  on	
  the	
  outer	
  face.	
   However,	
  in	
  the	
  construction	
  phase	
  of	
  the	
  building,	
  the	
  wood	
  sheathing	
  material	
  will	
  be	
   	
    5	
    exposed	
  to	
  moisture.	
  The	
  duration	
  of	
  exposure	
  to	
  moisture	
  is	
  difficult	
  to	
  predict.	
  It	
  can	
  take	
   days,	
  weeks,	
  or	
  even	
  months	
  for	
  the	
  building	
  envelope	
  to	
  be	
  closed.	
  Before	
  such	
  closure	
  the	
   sheathing	
  can	
  be	
  exposed	
  to	
  sun,	
  wind,	
  rain,	
  and	
  snow	
  without	
  any	
  protection.	
  Hence,	
  if	
   interior	
  rated	
  fire	
  retardant	
  coatings	
  are	
  used,	
  the	
  fire	
  retardant	
  may	
  be	
  leached,	
  reducing	
  the	
   performance	
  of	
  the	
  coating.	
  	
   To	
  be	
  classified	
  as	
  an	
  exterior	
  rated	
  fire	
  retardant	
  coating	
  by	
  the	
  National	
  Fire	
  Protection	
   Agency	
  (NFPA),	
  the	
  coating	
  has	
  to	
  be	
  subjected	
  to	
  a	
  laboratory	
  test.	
  Coatings	
  that	
  will	
  be	
   exposed	
  to	
  the	
  weather	
  or	
  conditions	
  of	
  80%	
  humidity	
  or	
  higher	
  must	
  pass	
  the	
  “Standard	
  Rain	
   Test“	
  (NFPA,	
  2009).	
  The	
  test	
  involves	
  exposing	
  samples	
  to	
  12	
  one-­‐week	
  conditioning	
  cycles	
  with	
   extreme	
  water	
  exposure	
  and	
  drying	
  cycles.	
  The	
  amount	
  of	
  water	
  exposure	
  is	
  the	
  equivalent	
  of	
   over	
  2000cm	
  of	
  rain	
  over	
  the	
  12	
  week	
  period	
  (WWPI,	
  2005).	
  This	
  test	
  ensures	
  that	
  the	
  FSR	
  of	
   the	
  coated	
  material	
  does	
  not	
  change	
  when	
  it	
  has	
  been	
  exposed	
  to	
  extreme	
  conditions.	
  	
   The	
  Alberta	
  Fire	
  Code	
  does	
  not	
  specify	
  whether	
  exterior	
  or	
  interior	
  coatings	
  must	
  be	
  used.	
  It	
   only	
  states	
  that	
  the	
  fire	
  retardant	
  coating	
  must	
  have	
  a	
  class	
  “A”	
  FSR	
  (Markusoff,	
  2009).	
  The	
  fire	
   code	
  assumes	
  that	
  the	
  wood	
  sheathing	
  will	
  be	
  used	
  in	
  an	
  interior	
  application,	
  but	
  it	
  does	
  not	
   take	
  into	
  account	
  that	
  the	
  sheathing	
  may	
  be	
  exposed	
  to	
  the	
  elements	
  in	
  the	
  construction	
  stage.	
   If	
  an	
  interior	
  fire	
  retardant	
  coating	
  is	
  used,	
  much	
  of	
  its	
  ability	
  to	
  retard	
  fire	
  could	
  be	
  lost,	
  as	
   mentioned	
  above	
  (CWC,	
  2000).	
   Fire	
  retardant	
  coatings	
  may	
  also	
  be	
  subject	
  to	
  mechanical	
  wear	
  and	
  damage	
  when	
  they	
  are	
   used	
  to	
  coat	
  panels.	
  Building	
  materials	
  are	
  not	
  usually	
  treated	
  with	
  the	
  utmost	
  care	
  and	
  can	
  be	
   damaged	
  by	
  accident	
  or	
  carelessness.	
  Fire	
  retardant	
  coatings	
  are	
  not	
  capable	
  of	
  withstanding	
   much	
  wear	
  and	
  damage	
  which	
  can	
  greatly	
  diminish	
  their	
  effectiveness	
  (Price,	
  2001).	
  	
   3.2	
  Application	
  Issues	
   To	
  comply	
  with	
  the	
  Alberta	
  Fire	
  Code,	
  a	
  fire	
  retardant	
  coating	
  with	
  a	
  class	
  “A”	
  FSR	
  approved	
  by	
   the	
  Underwriter’s	
  Laboratories	
  of	
  Canada	
  must	
  be	
  applied	
  to	
  panels.	
  To	
  maintain	
  this	
   designation,	
  the	
  fire	
  retardant	
  coating	
  must	
  be	
  applied	
  by	
  a	
  trained	
  professional	
  or	
  a	
   representative	
  from	
  the	
  company	
  that	
  manufactures	
  the	
  product	
  (Schwarz,	
  2003).	
  This	
  ensures	
    	
    6	
    that	
  the	
  coating	
  is	
  applied	
  evenly,	
  and	
  at	
  the	
  specified	
  thickness.	
  The	
  lather	
  is	
  important	
  to	
  the	
   coating’s	
  ability	
  to	
  achieve	
  the	
  desired	
  fire	
  retardant	
  properties	
  (Fire	
  Retardants	
  Inc,	
  2010).	
  The	
   requirement	
  of	
  having	
  an	
  expert	
  apply	
  the	
  coating	
  increases	
  the	
  cost	
  and	
  the	
  time	
  involved	
  in	
   coating	
  panels.	
   There	
  are	
  also	
  many	
  issues	
  with	
  onsite	
  application.	
  The	
  surface	
  of	
  the	
  wood	
  sheathing	
  needs	
  to	
   be	
  dry,	
  clean,	
  and	
  relatively	
  smooth	
  (No-­‐Burn,	
  2008).	
  On	
  a	
  construction	
  site,	
  conditions	
  are	
  less	
   than	
  ideal.	
  Keeping	
  a	
  wood	
  panel	
  clean	
  and	
  dry	
  can	
  be	
  difficult.	
  Also,	
  the	
  low	
  temperatures	
  at	
   the	
  jobsites	
  can	
  increase	
  the	
  time	
  required	
  for	
  coatings	
  to	
  cure.	
  Some	
  latex	
  intumescent	
   coatings	
  have	
  a	
  curing	
  time	
  of	
  about	
  48	
  hours.	
  In	
  this	
  time	
  the	
  ambient	
  temperature	
  must	
   exceed	
  10⁰C	
  for	
  the	
  coating	
  to	
  cure	
  properly	
  (Quantum	
  Chemical,	
  2011).	
  During	
  the	
  winter,	
   such	
  temperatures	
  rarely	
  occur,	
  particularly	
  in	
  Alberta.	
   It	
  is	
  also	
  difficult	
  to	
  apply	
  coatings	
  to	
  OSB.	
  All	
  fire	
  retardant	
  coatings	
  require	
  that	
  the	
  surface	
  of	
   the	
  substrate	
  be	
  somewhat	
  smooth	
  and	
  free	
  of	
  surface	
  imperfections.	
  OSB	
  usually	
  has	
  a	
  rough	
   surface	
  (Evans	
  &	
  Cullis,	
  2008).	
  Furthermore,	
  the	
  surface	
  is	
  often	
  contaminated	
  by	
  resin,	
  wax,	
   and	
  various	
  chemicals	
  (Quantum	
  Chemical,	
  2008).	
  These	
  components	
  can	
  reduce	
  the	
  adhesion	
   of	
  a	
  coating	
  to	
  the	
  surface	
  of	
  the	
  OSB	
  and	
  thus	
  reduce	
  the	
  performance	
  of	
  the	
  coating.	
  Hence,	
   prior	
  to	
  application	
  of	
  fire	
  retardant	
  coatings,	
  oils,	
  waxes,	
  and	
  resins	
  must	
  be	
  removed	
  from	
  the	
   surface	
  of	
  OSB.	
  The	
  removal	
  of	
  the	
  substances	
  is	
  difficult.	
  Sanding	
  the	
  surface	
  of	
  OSB	
  can	
   remove	
  such	
  contaminants	
  but	
  sanding	
  of	
  OSB	
  reduces	
  its	
  resistance	
  to	
  fire	
  (Evans	
  &	
  Cullins,	
   2008).	
  To	
  deal	
  with	
  the	
  contamination	
  of	
  the	
  surface	
  of	
  OSB,	
  a	
  basecoat	
  of	
  primer	
  should	
  be	
   applied.	
  Fore	
  example,	
  a	
  basecoat	
  of	
  latex	
  primer	
  is	
  highly	
  recommended	
  when	
  a	
  SafeCoat	
   latex	
  intumescent	
  coating	
  is	
  applied	
  to	
  OSB	
  (Quantum	
  Chemical,	
  2011).	
  This	
  requirement	
  is	
   costly	
  and	
  time	
  consuming.	
  	
   3.3	
  Cost	
  of	
  Coating	
  Systems	
   Fire	
  retardant	
  coatings	
  can	
  be	
  an	
  expensive	
  way	
  to	
  improve	
  the	
  fire	
  retardant	
  abilities	
  of	
  wood	
   products.	
  The	
  coatings	
  themselves	
  are	
  quite	
  expensive.	
  Product	
  prices	
  are	
  on	
  average	
  around	
   $90-­‐100	
  per	
  gallon.	
  Prices	
  of	
  coatings	
  vary	
  depending	
  on	
  their	
  quality,	
  performance	
   characteristics,	
  whether	
  they	
  are	
  exterior	
  rated,	
  and	
  whether	
  they	
  have	
  the	
  ability	
  to	
  inhibit	
  the	
   	
    7	
    growth	
  of	
  fungi	
  or	
  mold.	
  CeasefireTM	
  latex	
  intumescent	
  coating,	
  another	
  “class	
  A”	
  fire	
  retardant	
   product,	
  retails	
  for	
  approximately	
  $100	
  per	
  gallon	
  (Ceasefire	
  Technologies,	
  2011).	
  Two	
  (low	
  and	
   high)	
  estimates	
  of	
  using	
  a	
  Ceasefire	
  coating	
  system	
  are	
  shown	
  in	
  Figure	
  1.	
  	
    	
   Figure	
  1:	
  Estimated	
  Costs	
  of	
  Coating	
  a	
  4’	
  x	
  8’	
  OSB	
  Panel	
  (Ceasefire	
  Technologies,	
  2011)	
    The	
  low	
  estimate	
  does	
  not	
  include	
  a	
  primer	
  basecoat	
  or	
  a	
  weather-­‐protecting	
  top	
  coat.	
  To	
   achieve	
  the	
  best	
  fire	
  retardant	
  results	
  on	
  OSB,	
  a	
  primer	
  basecoat	
  is	
  required.	
  Also,	
  if	
  the	
  panel	
  is	
   to	
  be	
  exposed	
  to	
  excessive	
  humidity	
  or	
  rain,	
  a	
  topcoat	
  of	
  weather	
  and	
  wear	
  resistant	
  finish	
  is	
   required	
  (Ceasefire	
  Technologies,	
  2011).	
  Both	
  the	
  basecoat	
  and	
  the	
  topcoat	
  will	
  greatly	
   increase	
  the	
  cost	
  of	
  the	
  fire	
  retardant	
  coating	
  system,	
  as	
  the	
  graph	
  above	
  shows.	
  Also,	
  the	
   graph	
  above	
  does	
  not	
  include	
  the	
  costs	
  of	
  applying	
  the	
  coating.	
  Since	
  the	
  individual	
  applying	
   the	
  coating	
  must	
  be	
  certified	
  by	
  the	
  Underwriter’s	
  Laboratories,	
  the	
  cost	
  of	
  using	
  the	
  coating	
   will	
  increase.	
  Labour	
  cost	
  will	
  be	
  almost	
  tripled	
  if	
  a	
  basecoat	
  or	
  topcoat	
  are	
  required.	
   Furthermore	
  it	
  is	
  time	
  consuming	
  to	
  apply	
  the	
  three	
  coatings	
  and	
  wait	
  for	
  them	
  to	
  fully	
  cure.	
   The	
  costs	
  associated	
  with	
  fire	
  retardant	
  coatings	
  decrease	
  their	
  appeal	
  as	
  fire	
  retardant	
   systems.	
  	
    	
    8	
    4.0	
  Comparison	
  of	
  Coatings	
  to	
  Other	
  Systems	
   4.1	
  Coating	
  Versus	
  Treatment	
   Fire	
  retardant	
  treatments	
  were	
  once	
  the	
  primary	
  way	
  of	
  making	
  wood	
  products	
  more	
  fire	
   resistant.	
  However,	
  fire	
  retardant	
  coatings	
  have	
  many	
  advantages	
  over	
  fire	
  retardant	
   treatments.	
  First	
  and	
  most	
  importantly,	
  fire	
  retardant	
  treatments	
  can	
  only	
  be	
  applied	
  to	
  solid	
   wood	
  and	
  plywood	
  and	
  not	
  to	
  OSB	
  or	
  most	
  other	
  engineered	
  wood	
  products	
  (Williamson,	
   2002).	
  This	
  is	
  a	
  problem	
  because	
  OSB	
  is	
  a	
  widely	
  used	
  for	
  sheathing	
  in	
  residential	
  construction.	
   The	
  second	
  drawback	
  of	
  fire	
  retardant	
  treatments	
  is	
  that	
  the	
  treatment	
  cannot	
  be	
  applied	
  to	
   the	
  building	
  material	
  in	
  the	
  field.	
  Pressure-­‐treatment	
  must	
  be	
  done	
  at	
  a	
  special	
  treatment	
   facility.	
  Hence,	
  the	
  fire	
  retardant	
  panels	
  cannot	
  be	
  customized	
  to	
  their	
  purpose.	
  Fire	
  retardant	
   treatments	
  require	
  large	
  loadings	
  of	
  chemicals	
  compared	
  to	
  coatings	
  with	
  retentions	
  of	
  10-­‐20%	
   by	
  weight	
  (Plotnikova,	
  Egorov,	
  &	
  Khaliullin,	
  2003).	
  Such	
  high	
  retentions	
  increase	
  the	
  total	
  cost	
   of	
  fire	
  retardant	
  chemicals.	
  Furthermore,	
  many	
  of	
  the	
  fire	
  retardant	
  treatments	
  can	
  have	
  the	
   adverse	
  effects	
  on	
  the	
  wood’s	
  strength,	
  hygroscopicity,	
  stability,	
  toxicity,	
  adhesion,	
  and	
   receptivity	
  to	
  paints	
  (Price,	
  2001).	
  The	
  drawbacks	
  of	
  fire	
  retardant	
  treatments	
  and	
  the	
  inability	
   to	
  apply	
  them	
  to	
  OSB	
  make	
  them	
  unsuitable	
  for	
  a	
  fire	
  protection	
  system	
  for	
  the	
  Alberta	
  Fire	
   Code.	
  	
   4.2	
  Coatings	
  Versus	
  Gypsum	
  Sheathing	
   Exterior	
  gypsum	
  sheathing	
  can	
  be	
  used	
  instead	
  of	
  the	
  application	
  of	
  OSB	
  coated	
  with	
  fire	
   retardant	
  paint	
  to	
  comply	
  with	
  the	
  Alberta	
  Fire	
  Code	
  (FPB,	
  2010).	
  Gypsum	
  sheathing	
  is	
  a	
   cementitious	
  material	
  that	
  can	
  simply	
  be	
  nailed	
  or	
  screwed	
  to	
  the	
  exterior	
  face	
  of	
  OSB	
  panels	
  to	
   protect	
  them	
  from	
  fire.	
  The	
  main	
  advantage	
  that	
  fire	
  retardant	
  systems	
  have	
  over	
  gypsum	
   sheathing	
  is	
  the	
  ability	
  to	
  apply	
  the	
  coatings	
  to	
  irregular	
  or	
  custom	
  areas.	
  Coatings	
  can	
  be	
   applied	
  to	
  walls	
  without	
  having	
  to	
  measure	
  or	
  cut	
  any	
  pieces	
  to	
  specific	
  dimensions.	
  	
   Gypsum	
  sheathing	
  has	
  many	
  advantages	
  which	
  make	
  it,	
  in	
  many	
  cases,	
  a	
  more	
  suitable	
  system	
   for	
  improving	
  the	
  fire	
  retardancy	
  of	
  OSB	
  or	
  plywood	
  sheathing.	
  Firstly,	
  gypsum	
  sheathing	
   performs	
  better	
  than	
  coated	
  panels	
  in	
  fire.	
  Gypsum	
  is	
  a	
  completely	
  incombustible	
  material	
  and	
    	
    9	
    thus	
  its	
  fire	
  retardant	
  abilities	
  are	
  excellent.	
  Since	
  gypsum	
  is	
  incombustible,	
  the	
  FSR	
  and	
  SDI	
  of	
   gypsum	
  sheathing	
  are	
  both	
  zero	
  (Williamson,	
  2002).	
  Hence,	
  fire	
  will	
  not	
  spread	
  across	
  the	
   surface	
  of	
  gypsum	
  and	
  the	
  emission	
  of	
  toxic	
  gases	
  and	
  the	
  risk	
  of	
  flashover	
  are	
  eliminated.	
   Gypsum	
  sheathing	
  will	
  thus	
  be	
  a	
  better	
  system	
  for	
  reducing	
  intensity	
  and	
  the	
  spread	
  of	
   residential	
  fires	
  which	
  are	
  the	
  primary	
  goals	
  of	
  the	
  AFC.	
   Gypsum	
  sheathing	
  conforming	
  to	
  the	
  AFC	
  must	
  be	
  exterior	
  rated	
  and	
  able	
  to	
  stand	
  up	
  to	
   exposure	
  to	
  weather	
  and	
  mechanical	
  wear.	
  Exterior	
  gypsum,	
  unlike	
  many	
  fire	
  retardant	
   coatings,	
  does	
  not	
  lose	
  its	
  fire	
  retardant	
  abilities	
  when	
  it	
  has	
  been	
  exposed	
  to	
  the	
  elements	
   (ToolBase,	
  2003).	
  This	
  is	
  a	
  key	
  advantage	
  considering	
  that	
  panels	
  may	
  be	
  exposed	
  to	
  the	
   elements	
  and	
  mechanical	
  wear	
  during	
  building	
  construction	
  as	
  mentioned	
  above.	
  Hence,	
  fire	
   retardant	
  systems	
  using	
  gypsum	
  sheathing	
  will	
  retain	
  their	
  fire	
  retardant	
  ability	
  better	
  than	
   coatings	
  and	
  will	
  be	
  more	
  effective	
  in	
  buildings.	
  	
   Unlike	
  fire	
  retardant	
  coating	
  systems,	
  the	
  installation	
  of	
  gypsum	
  sheathing	
  does	
  not	
  require	
  a	
   high	
  quality	
  surface.	
  Gypsum	
  sheathing	
  can	
  be	
  directly	
  installed	
  onto	
  the	
  wood	
  panel	
  without	
   having	
  to	
  worry	
  about	
  the	
  condition	
  of	
  the	
  surface.	
  This	
  is	
  particularly	
  advantageous	
  when	
  OSB	
   is	
  the	
  sheathing	
  material	
  that	
  requires	
  fire	
  protection.	
   Gypsum	
  sheathing	
  is	
  a	
  more	
  cost	
  effective	
  method	
  for	
  improving	
  the	
  fire	
  retardancy	
  of	
  panels	
   than	
  intumescent	
  coating	
  systems.	
  This	
  may	
  be	
  the	
  most	
  important	
  advantage	
  of	
  choosing	
   gypsum	
  sheathing	
  as	
  a	
  fire	
  retardant	
  system.	
  The	
  cost	
  of	
  a	
  gypsum	
  sheathing	
  system	
  includes	
   the	
  material	
  cost	
  of	
  the	
  gypsum	
  sheathing,	
  and	
  the	
  labour	
  cost	
  associated	
  with	
  installation.	
   Exterior	
  gypsum	
  sheathing	
  that	
  meets	
  the	
  Alberta	
  Fire	
  Code	
  can	
  be	
  bought	
  in	
  a	
  variety	
  of	
  sizes.	
   Sheets	
  8’	
  by	
  4’	
  and	
  a	
  thickness	
  of	
  0.5”	
  can	
  be	
  purchased	
  for	
  approximately	
  $16	
  compared	
  to	
   $21.50	
  or	
  $27.50	
  for	
  the	
  cost	
  of	
  coating	
  an	
  8’	
  by	
  4’	
  sheet	
  with	
  fire	
  retardant	
  finishes.	
  This	
   material	
  cost	
  can	
  also	
  be	
  converted	
  into	
  a	
  price	
  per	
  square	
  foot	
  and	
  compared	
  to	
  the	
  price	
  per	
   square	
  foot	
  of	
  a	
  fire	
  retardant	
  coating	
  (Table	
  3).	
    	
    10	
    Table	
  3:	
  Cost	
  of	
  Coating	
  System	
  Compared	
  to	
  a	
  Gypsum	
  System	
  (Ceasefire	
  Technologies,	
  2011,	
   ToolBase,	
  2003)	
    Fire	
  Protection	
  System	
    Cost	
  ($/ft2)	
    Low	
  Estimate	
  for	
  Coating	
  System	
    0.67	
    High	
  Estimate	
  for	
  Coating	
  System	
    0.85	
    Exterior	
  Gypsum	
  Sheathing	
    0.50	
    	
   The	
  price	
  per	
  square	
  foot	
  of	
  gypsum	
  sheathing	
  is	
  0.5	
  $/ft2	
  which	
  is	
  0.35	
  $/ft2	
  less	
  than	
  the	
  high	
   price	
  of	
  a	
  fire	
  retardant	
  coating	
  system,	
  and	
  0.17	
  $/ft2	
  less	
  than	
  the	
  low	
  price	
  for	
  the	
  coating	
   system.	
  The	
  former	
  saving	
  is	
  probably	
  more	
  accurate	
  since	
  gypsum	
  sheathing	
  should	
  be	
  able	
  to	
   match	
  the	
  performance	
  of	
  the	
  full	
  fire	
  retardant	
  coating	
  system.	
  Table	
  4	
  shows	
  the	
   approximate	
  costs	
  of	
  different	
  fire	
  retardant	
  systems	
  used	
  in	
  a	
  small	
  house.	
  	
   Table	
  4:	
  Costs	
  of	
  Using	
  Fire	
  Retardant	
  Systems	
  to	
  Protect	
  a	
  House*	
  (Building	
  a	
  Home	
  Info,	
  2010)	
    Fire	
  Protection	
  System	
    Cost	
  ($)	
    Coating	
  System	
  (fire	
  retardant	
  coat	
  only)	
    1,951	
    Coating	
  System	
  (basecoat,	
  fire	
  retardant	
  coat,	
  topcoat)	
    2,475	
    Gypsum	
  Sheathing	
  System	
    1,456	
    *1500ft2	
  three	
  bedroom	
  house	
  with	
  attached	
  garage	
   The	
  cost	
  of	
  the	
  coating	
  systems	
  for	
  the	
  house	
  mentioned	
  above	
  are	
  significantly	
  more	
  than	
   using	
  a	
  gypsum	
  sheathing.	
  The	
  less	
  expensive	
  coating	
  system	
  is	
  about	
  34%	
  more	
  than	
  gypsum	
   sheathing	
  and	
  the	
  more	
  expensive	
  (exterior-­‐rated)	
  coating	
  system	
  is	
  about	
  70%	
  more	
  than	
  the	
   gypsum	
  system.	
  A	
  significant	
  amount	
  of	
  money	
  can	
  be	
  saved	
  using	
  a	
  gypsum	
  system	
  over	
  a	
   coating	
  system,	
  especially	
  in	
  larger	
  residential	
  buildings.	
  	
    	
    11	
    The	
  prices	
  and	
  costs	
  listed	
  in	
  Tables	
  3	
  and	
  4	
  only	
  show	
  the	
  cost	
  of	
  the	
  raw	
  materials.	
  The	
  use	
  of	
   gypsum	
  sheathing	
  also	
  has	
  the	
  advantage	
  of	
  lower	
  labour	
  costs.	
  Gypsum	
  sheathing	
  can	
  be	
   installed	
  by	
  the	
  construction	
  personnel	
  onsite,	
  unlike	
  fire	
  retardant	
  coatings,	
  as	
  mentioned	
   above.	
  This	
  means	
  that	
  the	
  installation	
  can	
  be	
  done	
  at	
  the	
  discretion	
  of	
  the	
  builders	
  and	
  there	
  is	
   no	
  need	
  to	
  hire	
  a	
  certified	
  individual,	
  which	
  lowers	
  the	
  cost	
  of	
  the	
  gypsum	
  sheathing	
  system	
   versus	
  fire	
  retardant	
  coatings.	
  The	
  lower	
  material	
  and	
  labour	
  costs	
  make	
  gypsum	
  sheathing	
  a	
   much	
  more	
  cost	
  effective	
  solution	
  than	
  the	
  use	
  of	
  fire	
  retardant	
  coatings.	
    5.0	
  Conclusion	
  and	
  Recommendations	
   The	
  use	
  of	
  fire	
  retardant	
  coatings	
  can	
  be	
  an	
  effective	
  way	
  of	
  protecting	
  structural	
  wood	
  panels	
   in	
  residential	
  buildings.	
  However,	
  they	
  have	
  some	
  limitations	
  that	
  affect	
  their	
  suitability	
  for	
   certain	
  applications.	
  The	
  lack	
  of	
  weather	
  and	
  wear	
  resistance	
  of	
  fire	
  retardant	
  coatings	
  limits	
   their	
  use	
  in	
  exterior	
  applications.	
  The	
  AFC	
  considers	
  fire	
  retardant	
  coatings	
  as	
  an	
  acceptable	
   means	
  of	
  protecting	
  wood	
  panels	
  for	
  new	
  construction	
  projects,	
  but	
  the	
  exposure	
  of	
  the	
   coatings	
  to	
  the	
  elements	
  is	
  not	
  considered.	
  	
   If	
  fire	
  codes	
  are	
  to	
  accept	
  the	
  use	
  of	
  fire	
  retardant	
  coatings	
  then	
  they	
  should	
  specify	
  that	
  the	
   coatings	
  must	
  be	
  protected,	
  almost	
  immediately,	
  from	
  the	
  elements	
  and	
  potential	
  sources	
  of	
   damage	
  and	
  wear	
  during	
  construction.	
  The	
  AFC	
  should	
  also	
  specify	
  whether	
  exterior	
  rated	
  fire	
   retardant	
  coatings	
  are	
  required	
  in	
  cases	
  of	
  prolonged	
  exposure	
  to	
  the	
  elements	
  during	
   construction.	
  Also,	
  research	
  must	
  be	
  done	
  to	
  ensure	
  that	
  panels	
  coated	
  with	
  interior	
  rated	
   coatings	
  retain	
  their	
  fire	
  retardant	
  ability	
  when	
  construction	
  of	
  the	
  building	
  is	
  complete.	
   Another	
  issue	
  with	
  coating	
  OSB	
  that	
  will	
  continue	
  to	
  inhibit	
  the	
  role	
  of	
  fire	
  retardant	
  wood	
   coatings	
  is	
  the	
  need	
  to	
  carefully	
  prepare	
  the	
  surface	
  and	
  apply	
  a	
  basecoat	
  of	
  primer.	
  This	
   increases	
  the	
  costs	
  and	
  the	
  time	
  required	
  to	
  coat	
  panels.	
  Unless	
  coating	
  companies	
  are	
  able	
  to	
   develop	
  cheaper	
  products	
  that	
  work	
  better	
  with	
  OSB,	
  their	
  usefulness	
  will	
  be	
  limited.	
   The	
  lower	
  material	
  and	
  labour	
  costs	
  associated	
  with	
  installing	
  a	
  gypsum	
  sheathing	
  system	
   makes	
  it	
  a	
  much	
  more	
  cost	
  effective	
  solution.	
  Than	
  fire	
  retardant	
  coatings.	
  Gypsum	
  will	
   maintain	
  its	
  cost	
  advantage	
  unless	
  cheaper	
  coatings	
  become	
  available.	
  The	
  considerable	
    	
    12	
    performance	
  and	
  cost	
  advantage	
  of	
  gypsum	
  sheathing	
  makes	
  it	
  more	
  economical	
  and	
  effective	
   than	
  fire	
  retardant	
  coatings	
  as	
  a	
  means	
  of	
  inhibiting	
  the	
  spread	
  and	
  impact	
  of	
  residential	
  fires	
   and	
  satisfying	
  the	
  Alberta	
  Fire	
  Code.	
   Fire	
  retardant	
  coatings	
  may	
  have	
  a	
  role	
  when	
  used	
  in	
  combination	
  with	
  gypsum	
  sheathing.	
   Gypsum	
  could	
  be	
  used	
  to	
  protect	
  as	
  much	
  of	
  the	
  paneling	
  as	
  possible	
  but	
  certain	
  areas	
  of	
  the	
   building	
  that	
  are	
  difficult	
  to	
  sheath	
  with	
  gypsum,	
  could	
  be	
  coated	
  with	
  a	
  fire	
  retardant	
  spray.	
   This	
  would	
  ensure	
  that	
  the	
  building	
  is	
  protected	
  better	
  than	
  by	
  an	
  entirely	
  gypsum	
  system	
  and	
   it	
  would	
  be	
  a	
  much	
  more	
  cost	
  effective	
  solution	
  than	
  applying	
  a	
  fire	
  retardant	
  coating	
  to	
  the	
   entire	
  building.	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
   	
    	
   	
   	
   	
   	
   	
    13	
    6.0	
  References	
    	
   Building	
  a	
  Home	
  Info,	
  2010.	
  Building	
  Materials	
  list	
  for	
  a	
  Three	
  Bedroom	
  Bungalow.	
   http://www.building-­‐a-­‐home-­‐info.com/building-­‐materials.html.	
  Accessed	
  March	
  30,	
  2011.	
   Canadian	
  Wood	
  Council	
  2000.	
  Fire	
  Retardant	
  Treated	
  Wood.	
   http://www.cwc.ca/NR/rdonlyres/77351FA7-­‐CC2B-­‐480B-­‐8EF4-­‐ 0DCC5379D17A/0/FireRetardantTreatedWood.pdf.	
  Accessed	
  February	
  11,	
  2011.	
   	
   Ceasefire	
  Technologies	
  2011.	
  Order	
  Ceasefire.	
   https://www.ceasefiretechnology.com/index.php?option=com_virtuemart&page=shop.browse &category_id=1&Itemid=3	
  Accessed	
  March	
  15,	
  2011.	
   	
   Evans,	
  P.D.	
  &	
  Cullis,	
  I.	
  2008.	
  Effect	
  of	
  sanding	
  and	
  coating	
  with	
  UV-­‐cured	
  finishes	
  on	
  the	
  surface	
   roughness,	
  dimensional	
  stability	
  and	
  fire	
  resistance	
  of	
  OSB.	
  Holz	
  als	
  Roh	
  und	
  Werkstoff	
  66(3):	
   191-­‐199	
   	
   Fire	
  Prevention	
  Bureau	
  2010.	
  Alberta	
  Fire	
  Code	
  2006.	
  AFC	
  5.6.1.2	
  –	
  Protection	
  	
  of	
  Adjacent	
   Building.	
  http://www.calgary.ca/docgallery/bu/fire/alberta_fire_code_5_6_1_2.pdf	
  Accessed	
   February	
  11,	
  2011.	
   	
   Fire	
  Retardants	
  Inc.	
  2010.	
  Fire	
  Retardants	
  101.	
   http://www.fireretardantsinc.com/fire_retardants101.html	
  Accessed	
  February	
  11,	
  2011.	
   	
   Garrison,	
  E.	
  2002.	
  Intumescent	
  Paints.	
  Architectural	
  Finishes.	
  Wiley	
  &	
  Sons,	
  New	
  Jersey.	
  	
  pp.	
   249-­‐253	
   	
   Gratton,	
  R.	
  2010.	
  Code	
  Changes	
  Related	
  to	
  Fire	
  in	
  Alberta.	
  Canadian	
  Home	
  Builders	
  Association.	
   http://www.chba.ca/TRC/October%202010/Alberta%20Report%20-­‐%20October%202010.pdf	
   Accessed	
  February	
  11,	
  2011.	
   	
   HIRF	
  2008.	
  Sparking	
  Fire	
  Safety.	
  Learnings	
  report.	
   http://aema.alberta.ca/documents/ema/HIRF_Learnings_Summary_F2.pdf	
  Accessed	
  February	
   23,	
  2011.	
   	
   Markusoff,	
  J.	
  2009,	
  March	
  13.	
  Home	
  builders	
  feel	
  burned	
  by	
  new	
  Alberta	
  safety	
  rules.	
  Calgary	
   Herald.	
   http://www.udialberta.com/2009.%20%20March%2013.%20%20Calgary%20Herald.%20%20Ho me%20builders%20feel%20burned%20by%20new%20Alberta%20fire%20safety%20rules.pdf	
   Accessed	
  February	
  23,	
  2011.	
   	
   National	
  Fire	
  Protection	
  Association	
  2009.	
  Standard	
  for	
  Fire	
  Retardant	
  treated	
  Wood	
  and	
  Fire	
   Retardant	
  Coatings	
  for	
  Building	
  Materials.	
  NFPA,	
  Massachusetts.	
  	
   	
    	
    14	
    No-­‐Burn	
  2008.	
  No-­‐Burn’s	
  Specialty	
  Intumescent	
  Coating	
  Continues	
  to	
  Amaze.	
  	
   http://noburn.com/all-­‐news-­‐articles/158-­‐from-­‐good-­‐to-­‐great-­‐no-­‐burn-­‐specialty-­‐intumescent-­‐ coating-­‐continues-­‐to-­‐amaze	
  Accessed	
  February	
  28,	
  2011.	
   	
   P1M	
  2008.	
  Paint	
  Coverage	
  Chart.	
  http://www.p1m.com/pcc.htm	
  Accessed	
  March	
  15,	
  2011.	
   	
   Plotnikova,	
  G.	
  V.,	
  Egorov,	
  A.	
  N.,	
  &	
  Khaliullin,	
  A.	
  K.	
  2003.	
  Fire	
  Retardants	
  for	
  Wood.	
  Russian	
   Journal	
  of	
  Applied	
  Chemistry,	
  76	
  (2):	
  310-­‐313.	
   	
   Price,	
  D.	
  2001.	
  Chemistry	
  of	
  Fire	
  Retardancy.	
  Fire	
  Retardant	
  Materials,	
  9.2,	
  pp.	
  297-­‐306.	
  	
   	
   Przybylak,	
  M.	
  W.	
  &	
  Kozlowski,	
  R.	
  1999.	
  The	
  Thermal	
  Characteristics	
  of	
  Different	
  Intumescent	
   Coatings.	
  Fire	
  And	
  Materials,	
  23	
  (1):	
  33-­‐43.	
   	
   Quantum	
  Chemical	
  2011.	
  SafeCoat	
  Latex	
  Intumescent	
  Coating.	
  MSDS	
  and	
  information	
  sheet.	
   http://www.quantumchemical.com/images/stories/PDFs/SC%20Latex%20March%202011.pdf	
   Accessed	
  February	
  28,	
  2011.	
   	
   Schwarz	
  2003.	
  Coatings	
  that	
  can	
  save	
  lives.	
  Coatings	
  World.	
   http://findarticles.com/p/articles/mi_hb053/is_11_8/ai_n29044423/	
  Accessed	
  February	
  11,	
   2011.	
   	
   ToolBase	
  2003.	
  Alternatives	
  to	
  Structural	
  Plywood	
  and	
  OSB.	
  	
   http://www.toolbase.org/Design-­‐Construction-­‐Guides/Interior-­‐Partitions-­‐Ceilings/plywood-­‐ alternatives.	
  Accessed	
  February	
  28,	
  2011.	
   	
   Western	
  Wood	
  Preservers	
  Institute	
  2005.	
  Fire	
  Tests	
  for	
  Pressure	
  Fire	
  Retardant	
  Treated	
  Wood.	
   Treated	
  Wood	
  News.	
   http://www.wwpinstitute.org/mainpages/documents/Dec05_FireTests_WWPI.pdf	
  Accessed	
   March	
  21,	
  2011.	
   Williamson,	
  T.	
  G.	
  2002.	
  Basics	
  of	
  Fire	
  Protection.	
  APA	
  Engineered	
  Wood	
  Handbook.	
  10.1.1	
   	
    	
    15	
    

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