A few interesting things about Roofing

Without much ado  or  taking  for granted anything,  let me  start  by  saying that  the  roof is the upper-most part of a building structure. Erecting a roof is a specialist work   done by   trades personnel called roofers and   is as complex as it is   delicate. This explains why most contractors avoid it by   subcontracting   it out.  Roofing requires greater skill and workmanship  ,especially  because  a roof is the most  visible  part  of  a building . And your guess is  as good  as mine ,that most  customers   will not  tolerate  second rate  skills  that  may   compromise the  bold statement   the  roof  is  supposed to make ;people want   the  heads  of  all  and  sundry  to keep turning . Indeed homes are built on foundation of wisdom, but a roofs makes a house. If the roof is not good, the building will be shed not a house.

In designing  a roof, the  builder    must  consider   the  need  for  shelter  from the elements  as well  as   the need  to conserve  heat  and  fuel. Where a roof type chosen   is the kind that sheds heat to the night air faster, then insulation measure must be built into the roof.

There are three main types of roofs, classified on the basis of their steepness or pitch:

  1. Pitched
  2. Flat
  3. Others-Dome, Barrel, and Hyperbolic.

The pitch of a roof is the angle it makes or the roof Rafter makes with horizontal line parallel to the ground. Anything less than 10◦ is considered   a flat roof, and anything greater than 80◦is considered a wall. A  steep roof  of  more  than 40◦   uses  more  material  and  has more  dead weight   than   less  steep  roof.

Softwood  is  used  to  construct  the  structure   of  most  roofs, which is  then covered  by iron sheets, clay  tiles,  stones,    cedar  wood  shingles  , asphalt  shingles,  reeds,  straw  or  even  need  grass  depending building specifications  and  how prepared   the  owner   is ,to  dig  deeper  into  his  pockets.

Generally  speaking ,  roofs   protect us from the  elements, provide  stability  to  the  walls(without it  the  top  of the wall  will be  weak) and    insulate us   from   heat  and  sound.

Pitched roofs

Pitched roofs can be cut at the site or be prefabricated. Prefabricated roofs  are  factory  made    and  delivered  to  the  site, in assembly  sections  ready  for erection.Wastage  is  minimized  with  prefabricated  roofs   because  ,off-cuts  can  be  finger  jointed  together  to  form  longer  lengths  and  used. Pitched  roofs  must be  ventilated  to  remove  water  vapour  and  eliminate the risk of  condensation. This  ventilation can be  through soffit  board with either holes  backed  with  insect  mesh  to  prevent  wasps  and  bees  from entering the  roof  space  between the  cover and ceiling board. The  other  approach  is to  have  the  fascia  board  ventilated  .To  ensure efficient  ventilation, high  level  vent  can be  installed  at  the ridge  or  ventilation tile  should be  used.

Parts of a Pitched roof

1.Rafter-A long and strong piece of timber that runs from the ridge to the wall plate on slopping roof.

2.Strut- A piece of  wood that  support the roof  and  run  between rafter  and  ceiling joist.

3.Ceiling Joist-A long piece of  timber  put below the ceiling  and fixed on the wall plate  to  support   both  the  rafter (erected  above  it)  and ceiling board( below it).

4.Ridge-A raise top or a line formed between the two sloping sides of a roof.

5.Wall plate- A piece of metal used to cover and protect to topmost course of a wall from the drown thrust of the ceiling joist.

6.Collar-a short piece of timber that run parallel and above   the ceiling joist, but hold together two, sloping rafters.

7.Fascia board- A board  that  fixed  round  a  roof cover  overhanging  the external  walls  and  used  to  protect the roof void  from elements.

8.Soffit board-board that lies horizontal and fixed between the fascia board and the external walls.

9.Valley- A low line formed at the intersection of two sloping sides of a roof.

9.Truss-A wooden frame made up of two sloping Rafters, Struts and Ceiling joist. Several trusses are need to erect a roof. They are also called Trussed rafters.(see image  above).

 

©Copyright2017: eastafricaminihardware.com

Sources: Building in the 21 Century by Robert Cooke.

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