Thursday 26 February 2015

BUILDING PROTECTION: THERMAL INSULATION ...........

§  Thermal  insulation  may  be  defined  as  a  parries   to  the  natural  flow of  heat  from  an area  of  high  temperature  to  an area  of  low  temperature.
§  In  buildings  this  flow  is  generally  from  the  interior  to  the  Exterior.
§  The  flow  of heat  through  the  solid  walls  of  the  buildings  is  mainly  by  conduction,
§  The  amount  of  heat  transmit  depending  on:- 
                   i.        The  temperature  difference  between  the two  surfaces,
                ii.        The thickness  of  the  immediate  medium,
             iii.        The  area  of  the  exposed  materials, 
              iv.        The  time  of  heat  flow and
                 v.        The  rate  of  heat  transfer of  the  conductions  of  the  intervening  materials.

Factors  influencing  the  flow  of  heat  from  the exterior into  the  interior of  the  building:-
i.           Thermal  conductivity  of  the  external  walls  of  the  building  e.g. Walls, roof and  floors 
ii          Deference  of  temperature  between  both  the  faces  of  the  walls
iii.     The area of the external walls of the building.
iv.      The total area covered by doors and windows.
v.         The  rate  of  air  movement  through  the, enclosed   spaces  within  the  building  or  walls.

Types of insulting materials

There  are  various  types  of  insulating  materials  which are  describes  a s  follows :-

Block Insulation
It  is  made  up  of  cork  boards, cellular  glass  blocks, rubber  blocks, mineral wood  blocks  or  wood  fibers  bound  together  with  cement.

Blanket Insulation
 These  are made  up of   flexible  fibers  materials  and  are  available  in  rolls and Its  thickness  varies  from  10 to 80 mm.

 Batts Insulation
These  are  soft  materials  similar of blanket insulations, but  are  smaller  in size  and greater  in  thickness.

 Loose fills
The  materials  like  glass  wool, wood  fibre, slag  wool  etc  are  loosely   pored  into  the  studding  space  and  other  similar  spaces.

 Economics of thermal Insulation
§  By  providing  the  thermal  insulation in  the  building , considerable  expenditure  in  heating, cooling   or air condition  is saved.
§  Moreover   the  temperature  inside  the  building  is  maintained  more  uniformly

Note; before fixing a particular type of insulation materials, the economic feasibility should be also considered.

The  following  factors  need  careful  consideration  while  considering  the  economic  feasibility  of  thermal   insulting  materials:-

   i.        The  cost  of  insulating  material 
ii.        The cost of  placing  and  fixing  the  insulation
iii.        The  education in  the  cost  of  heating  and  cooling
iv.        The rescuing expenditure to maintain the standard of insulation.


A  CAUSTICS   AND   SOUND    INSULATION

The  term  “ a caustics” may  be  defined  as  the  science  of  sound, and  it  describes  the  origin, propagation  and  sensation  of  sound

What is sound?
Anything  that  can  be  heard is  a sound, whether  it  is made  by  conversation  machinery  or  walking  on  a hard  surface.

Sound can differ   in two important ways,
§  By  loudness
§  By pitch.

 A  sound  is  produced  when the  medium  enclosing  the  body  is  compressed  suddenly.  A sound   travels in the form of wave through certain medium.

when  a  sound  is produced  within  the  building  three  reactions  can occur
   i.        The pressure  or  sound  waves  can  come  into  the  contact  with  the walls  floor  and  ceiling  and be  reflected  back  into  the  building.
ii.        Some of  the  sound can  be  absorbed  by  these  surfaces  and  / or  the  finishes.
iii.        The  sound  waves  upon  reading  the  walls, floor  and  ceiling  can  set  these  members vibrating  in  unison  and  thus  transmit  the  sound  to  adjacent  rooms .

What is Noise?
A  noise  can  be  defined  as  any  undesired  sound and  may  have  any  one  of the  following  four  effects  on  man:-
i.   Annoyance
ii.                Disturbance  of  sleep
iii.             Interfere  with  the  ability  to hold normal  conversation
iv.              Damage of hearing.

The  approach  to  solve  noise  or  sound  problems  can  be:

i.   Reduce  the  noise  emitted  at  the  source  by  such  dances  as  mufflers and  mounting on resilient  pads.
ii.                Provide a reasonable degree of sound insulation reduce the amount. of  sound  transmitted
iii.             Isolate  the  source  and  the  receiver
iv.              Provide  required standard  of  walls  or  floor  structures  and  finish  which  can  reduce  sound  transmission.

External noise
The  main  barrier  to  external  noise  is  provided  by  the  shell  or  envelopes  of  the  building, the  three  main  factors  being:-
i.   The mass  of  the enclosing  structure
ii.                The  continuity  of  the  structure 
iii.             Isolation  by  double  leaf construction  or  cavity  wall  construction  when using light  weight  materials.

Terminologies

Thermal conductivity
Is  the measure of materials, ability  to transmit hear  and  Expressed as the  head  flow  in  watts per  m2

Thermal resistively 
this  is  the ability  of a materials, regardless of  size  or thickness, to resist  the passage  of  heart  and is the  reciprocal  of the  thermal  conductivity.

Thermal resistance
This is the product of thermal resistant and thickness in metres.

SOUND INSULUTION IN FLOORS

The following floors structures and finisher can be used to reduce the transmission of sound. Refer sketches, Construction technology hand book; author Childley

Concrete floors



















 Floating timber rafter
   







     

 









Timber floating floors
















FIRE PROTECTION:

Fire  protection is  the  protection of  the  occupants, occupants and structure  of  a building  from  the  risks   associated with  fire.

It  is  practically  impossible  to eliminate  completely  the  chances of  fire  in a  building  as  it  is  a fact  that  no  building  materials  is  fully  fire  proof.

Characteristics of five- resisting materials
i.   The  material  should be  composed  of  such  elements  which  do not  disintegrate  under  the  effect of greeter heat
ii.                The materials  should  have low  co- efficient of thermal  expansions, so  that  the  excessive  expansion  of  a  particular  member  which  may  lead  structural  instability  is prevented.
iii.             The  materials  should  not  contract  rapidly  when  it  is  cooled with  water  at high  temperature.
iv.              The materials should be compact which cannot easily catch fire.


Fire resisting propertied of common building materials

§  Stone
The stone is a bad conductor of heat.
The stone  disintegrates  into  small  pieces  when  is  healed  and suddenly  cooled.

§  Bricks
 is  a bad  conductor  of  hint  and  it  is  rest  heat  up to  120c0
If  the  quality  of  the  montar  and  workmanship  are  good, the  bricks  masonry
Resist afire & a greater extend.

§  Timber.
 Timber is a bad conductor of heat .
Timber ignites  and  get  rapidly  destroyed  in  case  of  fire.

§  Steel
Steel  is  a  good  conductor of  heat  and  therefore  it  is  quickly  heated  in  case of fire.
    
§  Concrete
Concrete is a bad conductor.
It can be used as an effective fire resisting materials.

General guide lines for fire proof of the buildings.

Alarm system
This  is  installed  to give  an  alarm  and  call  for  assistance in  case  of  fire. this  system  may be  automatic  or normal.

Protection of openings
The openings of the buildings should be well protected.
In case  of  fire, the inhabitants  of  the  building  can  come  out  from  these  protected  openings

Common wall
When  a fire- resisting  building  is  located  at  the  site  of  another  building
The  common wall  should  be  of  a  minimum  thickness  of  two  bricks.
The  common wall  should  be  raise  above  roof  level  by  at  least  one  meter.

  Stairs
Emergency stairs of a ladder should be provided   in the fire resisting building. The  ladder  should  made  with  fire  resisting  materials with  a  fire- proof  door.

Floors
the  floor  in  such  building should  be  of  R.C.C of at  least  150mm  thickness
the  floor  should  be prowled  with  out ward  slope  to  drain  the  water when – fire  fighters  are working.

 Fire extinguishing arrangements
This arrangement depends upon the importance of the building. The commonly used equipment for fire extinguishing equipment:-
   i.        Manual fire- extinguishing equipment
ii.        Internal hydrants
iii.        Automatic sprinkler installations



Topic No 4

FLOOR FINISHES

 Floor finishes for domestic buildings include a wide range of alternative

The  factors  that  may  influence  the  choice  of  floor  finish  depends on  the  use  of  the  floor  space  and  limits on cost.

The following should be considered for choice of floor finish.

 Resistance to Wear
The  type of  wear  that  is  normal  in  a  specific part  of  a building  so that  it  lasts many  years without  replacement.

Resistance to grease and oil
the  floor  should  not  be  manage  by  grease and  oil  spills  and  they  should  be  wiped up from the surface.

Easy of clearing
surfaces  that  allow  dirt  to  easily  penetrate  are harder  to  keep  clean. The choice of floor should be easily to be cleaned.

Tendency of reducing   noise
hard  surfaces  do  not  loser  sound so they  are nosier  than  soft  surfaces.

Economic factor 
The  costs  vary enormously  for the  huge range of finishes  e.g. cement  screed  is  more  cheaper  compared  to  carpet, wood  block or  floor  files.

Controlling of warmth or coolness
Hard, smooth surfaces are cool to walk on because they conduct heat away.
But  soft  textured  finishes  like  carpet  give  a room  a  warmer  feel, which  may  be  suitable for  cooler  dilates

 Resistance to water spills.
The flooring in bathroom sand kitchens need to withstand water spills from washing or plumbing leaks.

 Architectural beauty
The floor finish should provide good appearance eg. Floor tiles process good appearance compare to normal cement screed.

TYPES OF FLOOR FINISHES / FLOOR COVERINGS

 Concrete floor covering
§  Concrete floor covering is provided over the sub- flooring of about 150mm  thick
§  Normally  depending  on  the requirements  of thickness  of  floor  finish, on  top  of  concrete  bed,  the  cement  screed  is provided  acting  as flooring  finish.

Bricks
§  Are used as  covering  for  comparatively  cheap  flooring  for  ordinary   sheds, stores, temporary  barracks
§  Good  example  of  brocks  which  are  used  as  flooring  finish  is  engineering bricks.
§  Good  example of bricks  which  are  used as  flooring  finish  is  engineering  bricks.
§  Mixing ratio for mortar depends on the durability required.

 Terrazzo
§  The  finished  surface  consists  of about  10mm thick  top  layer  of  terrazzo  mixture    
     
 Procedure for construction of terrazzo
§  Prepare a marble chips  consists  of  3 to  6mm size
§  Mix  with  a white  or  colored  cement  in the proportion of 1: 2 or 1:3
§  Provide patients by  using  dividing strips  of  ( metal  20 gauge) or  glass  or  others  materials.
§  Then laid terrazzo in layers over the prepared surface.

Mosaic
§  The  sub  base is  similar  to terrazzo
§  A thick bedding 6 cm of lime mortal   is placed over the sub – base.
§  After  mortar has  hardened  a  3mm thick  layer  of cement  materials  costing  of  slaked  lime, powdered marble and  pozzolana  in  the  ration  of  2:1:1 is  load
§   After  4  hours  tales of Mable  slabs are kind  in the  specified  Patten
§  The top surface is left for 24 hours and them given a polishing of pumice stone.

Tiles
§  Tiles are placed on lime concrete or lean cement concrete base.
§  A  thin layer of 1:2 cement mortar   is placed  over  the  sub- base  and  tiles  of  required  shape ,size and  thickness  placed  over  the sub – base

Wooden blocks
§  The  flooring  is normally  constructed in  one  of  the  following  ways  Wood  block covering
§  The sub-bade consists of lime concrete of (1:6:12 or 1:8:16)
§  2 cm thick sand cushioning is provide
§  Then  a  blocks  of  wood  of  sizes  varying  from  20  to  30 in  length, 8 to  10cm  in width  are kind  and properly  joined together.

 Tiles
§  A thin layer of 1:2 cement mortar is placed over the sub- bade and tiles of required shape, size and thickness placed over the sub-base; there are different types of tiles one of them is

Vinyl asbestos tiles

§  These  tiles  are  prepared  in  varying  size  from  225 to 300mm squire  and  thickness of 1,2,3 mm etc.
§  They are available in variety of  colours
§  The  composition  of  the  tiles  is  asbestos  fibers  bonded  with  the 30% polyvinyl chloride (PVC)
§  Before  applying  to  wooden, timber  or  concrete surfaces they  are  warmed  and  foxed  to  the  surface  with  the  help  of bituminous  adhesives.
§  The  finished  surface  resists  mild  alkali  and  acid  attacks  and  is  not  easily  spoilt  by  grease.

 Wooden blocks
§  The flooring is normally constructed in one of the following ways.
§  The  sub- base  consist   of lime  cemerete of (1:6:12 or 1:8;16)
§  2cm  thick  sand  cushioning  is  provided
§  Then  a  blocks of  wood  of sizes  varying from  20 to 30 in   length  8, to  10 cm in width are  aid  and properly  joined together.

Glass
§  Structural  glass  is available in  different  patents and  sizo of  slay  carried  by  closely  spaced  frames
§  This  type  of  flooring  is  comparatively  delicate and can  take only      light  loads.
§  It  is  used  in situations  when  light  is required  through the  glass  flooring to the  floor  below.

Vinyl asbestos tiles
§  These  tiles  are  prepared  in  varying  size  from  225 to 300mm squire  and  thickness of 1,2,3 mm etc.
§  They are available in variety of  colours
§  The  composition  of  the  tiles  is  asbestos  fibers  bonded  with  the 30% plying  chloride (PNC)
§  -Before  applying  to  wooden, timber  or  concrete surfaces they  are  warmed  and  foxed  to  the  surface  with  the  help  of bituminous  adhesives.
§  The  finished  surface  resists  mild  alkali  and  acid  attacks  and  is  not  easily  spoilt  by  grease.

Carpet
§  These varies in term of  colour  materials  used and  Quality. And styles in term of decoration.
§  It cannot use for areas such as toilets or wet areas.

 CLASSIFICATION OF FLOOR FINISH MATERIALS

 INSITU FINISH MATERIALS
   i.        Cement  screed  and
ii.        Terrazzo

NON – INSIT FINISH MATERIALS
   i.        Mosaic  materials
ii.        Dividing  strips  eg. Metal, wood
iii.        Vinyl  asbestos  tiles eg.PVC  tiles
iv.        Blocks
 v.        Wooden  blocks
vi.        Capart
vii.        Skirting and dividing strip



GENERAL PROCEDURES FOR PREPARATION OF SURFACE

§  Hacking the existing surface
§  Prepare the materials required
§  Clean the surface before applying the required types of finishes


TOOLS USED DURING APPLYING FINISHING WORKS
§  A  bucket
§  A  mixing  board  and  shovel
§  Wood float and steel float
§  Screed board
§  Builders  level
§  Grating  machines  e.g for  terrazzo

GENERAL PROCEDURE FOR PREPARATION OF BASE
   i.        Hacking the existing structure  eg. Hacking concrete.
ii.        Clean the surface  or apply  special  treatment  of  base  required  e.g.  grouting  applying  bonding  agent
iii.        Prepare the materials  required  for  carrying  out  type of  finishes  eg. Preparation  of  mortar, chipping  etc.
iv.        Prepare tools required eg. Buckets  mixing  board and  shovel, wood  floor  or  steal  float, builders  level, screen  board  etc.

 NATURE OF THE BASE
§  concrete base
§  Brick work or  Block work  base
§  metal  lathing
§  screened  base
§  Timber base

SKIRTING

§  Also  is  the part  of  floor  finish 
§  It  is  the  component  which  separate  the ends  of floor  finish  and plaster.
§  Normally  is  applied  internally
§  It  can  be  cement  sand  screed, timber,   terrazzo, PVC tiles  etc. and standard  size  75- 100mm  width  and depth  of 15- 20mm
§  Architectural  beauty  required  the  skirting  to  relate  with  the type of floor  finishing  applied.

DIVIDING   STRIPS
§  These are used to provide patterns on the given surface.
§  It can  be  metal, wood  or  special  rubber  material 
§  It is mostly used during  applying terrazzo  finish.




































FLOORS STRUCTURES/ UPPER FLOORS

The  function of  any  floor  is  to provide a  level surface  which is  capable  of  supporting all  the live  and  dead loads  imposed.

In large- scale and multistorey  buildings  the  floors  are  normally  main structural elements  closely  related  to the  general structure of the buildings  and as such  they  must  be  considered  at  the  design  stage.

CHOICE OF FLOOR
The main factors influencing the choice of floor type are:

i.           Nature of the building;
           The following is more suitable
§  A precast  concrete floor  
§  steel  deck floor laid could  be  suitable
§  Insitu reinforced  concrete frame   

ii.        Loading
§  Flat slab construction is economical   for heavy uniformly distributed loading.

iii.      Span
§  With increase in the span  and ( in the  load) these  will  normally  be an  increase in the  thickness  and  weight of  a solid floor slab.

iv.      Degree of fire resistance required.
§  This is frequently a determining factor in the choice of floor.

v.         Provision  of  services
§  The large number of services and extensive equipment required in many building determine the types of floor to use.

vi.      Degree of sound insulation required.
§  Weight of structure is important in connection with insulation against air borne sound. The greater the weight the greater the insulation provided. 

vii.   Cost, speed of erection, adaptability.
§  Consideration of cost must enter in to the choice the floor type.

TYPES OF FLOORS

i)          Reinforced concrete floors
These  fall  into the  broad  categories insitu  cast and precast in each of  which  there list  a wide  variety  of  types.

Insitu cast floors
Because  of being wet during  construction  required temporary  support  until the concrete  is  strong  enough  to bear  its loads.

Types of floors under insitu cast floors.

§  Solid concrete floor slabs.
This type  is commonly  used  when the  slab  is  to  act as  a membrane  supporting on  columns  without  beams.

§  Flat slab floor.
This is the other form of insitu concrete floor without projecting beams.

The  system  is design for  heavy  evenly  distributed  superimposed loads and  is  economical for loading of  4.5  KN/M2

Suitable where there is no large openings or little solid partitions
§  Insitu hollow block floor.
This type of floor is lighter than the simple solid slab floor.

On this  type  the  blocks  are laid and  to end  in parallel  rows about  75 to 100mm apart, according to  the width  required.

Reinforcement is  laid  in  these spaces  and  concrete  poured  between  and  over t he blocks.

ii)       Precast floors
The use of precast floors reduces or eliminates the use of shuttering.

In  this type  units are made in  various  width and depth  vary  according  to span and load  required  in connection with  the arrangement  of  beams and  columns.

iii)   Steel deck  floors
The  deck units are relatively  light  in  weight , can be  quickly  hoisted  in  bundles  and  fixed  in position.

iv)     Open  grating  floors
This type of  flooring  is made  up  in steel , aluminum delay  or glass  reinforced  plastic in  panels of varying width  and  length required.

v)        Spring floors.
Gymnasium and dance floors should be resilient.
This resilience is imparted by the use of a sub – floor of timber bearers With or without springs or rockers.

vi)     Cavity  floors  or  Raised  floors
These  are  structural  sub- floors  raised  above the normal  floor  slab  to  form  cavity  to  accommodate example  Cables  etc.

Normally used in the areas such as laboratories and computer rooms etc

Cavity floors fallow into two types:-

§  Battened floors

These provide a shallow  cavity  for  cable server  usually  us  than  100mm in  depth and may  be  formed  by  timber  battens at 300mm centre  supporting  chipboard  flooring  in  which  there  are  removable strips over panels at  intervals.

§  Pedestal floors

These provide a deep cavity over 1000mm so that a normal cable   and environmental services can be accommodated. The  flooring  panels  are supported  on metal  props  or  pedestals which  are  adjustable  in height  to permit leveling of the  floor.

      vi)  Timber floors.
Also  this  is  another  type  of floor  which  is normally  used  where  the                                                              span and loading  required  is not  heavy.

It is  design  in  connection with  supporting  beams or  projecting  beams  in  order  to reduce  the  dead and live loads.

PROVSION FOR SERVICES IN FLOORS

Services  can  be accommodated  above  the structural slab, within  its natural  thickness, below  the slab  or  below  its  supporting  beams.

Services which can be provided;
i.   Electrical conduct
ii.                Pipes for water, heartily, gas or drainage services may be laid either on top of the slab fixed to or suspended from or the soffit.

When laid on top of the slab the thickness of the finishing screed may be considerable especially if some pipe cross each other










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