Measurement of Plinth Area and Carpet Area of a Building

Plinth area and carpet area of a building is measured for estimation and calculation of building cost. It is also a measure of usable space of building.

Plinth area is the covered built-up area measured at the floor level of any storey or at the floor level of the basement. Plinth area is also called as built-up area and is the entire area occupied by the building including internal and external walls. Plinth area is generally 10-20% more than carpet area.

Fig.1: Plinth Area of a Room in Building

Carpet area the covered area of the usable spaces of rooms at any floor. It is measured between walls to walls within the building and is the sum of the actual areas of the rooms where you can carpet.

Fig.1: Carpet Area of a Room in Building

Measurement of Plinth Area and Carpet Area of a Building

For measurement, the lengths and widths should be measured nearest to 0.01m and areas should be rounded to 0.01 m2. In Case of feet system, length should be measured to nearest 1 inch.

During the measurement, following categories are measured separately:

• Basement
• Floor without cladding (stilled floor)
• Floors including top floor which may be partly covered
• Garage
• Mezzanine floor

Measurement of Plinth Area

Following areas are included during measurement of plinth area:

1. Area of the wall at the floor level, excluding plinth offsets. If there are any common walls between two buildings, half of the area of such walls shall be considered in the plinth area. When building consists of columns projecting beyond the cladding, the plinth area is measured upto the external face of the cladding (in case of corrugated sheet, cladding outer edge of the corrugation is considered).
2. Areas of the internal shaft for sanitary installations and garbage chute, electrical, telecom and firefighting services provided these do not exceed 2 m2 in area.
3. Vertical duct for air conditioning and lift well including landing.
4. Staircase room or head room other than terrace level
5. Machine room
6. Porch
7. Open projections of veranda, balconies and parapets, if the area is protected by projections, full area is included in plinth area, if the area is un-protected by projections, 50% of the area is included.
8. Recess by cantilevering beyond external walls, bay window is the best example. If the recess height is up to 1.0 meter, 25% of such area shall be included. If the recess height is 1.0 to 2.0 meters, 50% of such area shall be included. If the recess height is above 2.0 meters, 100% of such area shall be included.

The following is not to be included in the calculation of plinth area:

1. Additional floor for seating in assembly buildings, theatres, auditoriums
2. Cantilevered porch
3. Balcony
4. Area of loft
5. Internal sanitary shaft and garbage chute, provided these are more than 2 m2 in area
6. Area of architectural band, cornice, etc.
7. Area of vertical sun breaker or box louver projecting out and other architectural features such as slab projection for keeping flower pots
8. Open platform
9. Terrace at first floor
10. Spiral staircase including landing
11. Towers, turrets, domes projecting above the terrace level at terrace.

Wall Area in Plinth Area Calculation

Wall area is also included in plinth area calculation. Wall area is the area on plan occupied by walls on any particular floor. It includes the thickness of any finishing or dado tiles if the height of such wall is more than 1m from floor finish.

Following should be included in wall area of the building:

1. Area on plan occupied by doors and other openings
2. Intermediate pillars, supports and other such obstructions within the plinth area irrespective of their locations
3. Pilasters along wall if exceeding 300 cm2 in area
4. Flues within the wall
5. Built-in cupboards, wardrobes, shelves appearing within a height of 2.2m from floor
6. Fire place projecting beyond the face of wall in living or bed room

The following is not included in wall area:

1. Pilaster along wall not exceeding 300 cm2 in are

2. Platforms projecting beyond the face of the wall

Measurement of the Carpet Area of the Building

Carpet area is the plinth area less the area of the following portions of the building:

1. Wall area
2. Veranda
3. Corridor and passage
4. Entrance hall and porch
5. Staircase and stair cover
6. Lift shaft and machine room for lift
7. Bathroom and lavatory
8. Kitchen and pantry
9. Store
10. Canteen
11. Air conditioning duct and plant room
12. Shaft for sanitary piping
13. Stilted floor and garage

For the calculation of approximate cost of the building using plinth area method, the sum of the built-up area of all floors including based basement is considered as the plinth area of the building.

Repair of Cracks in Concrete Structures

Grouting Procedure for Repair of Cracks in Concrete Structures:

Procedure of grouting for repair of concrete cracks in structures are:

1. Holes  are  drilled  in  structure  along  cracks  and  in  an  around  hollow spots.

2.If  there  are  several  cracks,  holes  can  be  drilled  in  a staggered  manner  at  500  to  750mm  spacing  in  both  directions covering  adequately  the  area  proposed  to  be  grouted.  Holes spacing  can  be  altered  as  per  site  conditions.

3. G.I.  pieces  (12  to  20mm  dia  x  200mm)  with  one  end  threaded  or PVC nozzles are fixed in the holes with rich cement mortar.

4. All  the  cracks  and  annular  space  around  G.I.  pipes  are  sealed  with rich  cement  mortar.

5. All  the  cracks  are  cut  open  to  a  ‘V’  shaped groove, cleaned & sealed with rich cement mortar.

6. All  the  grout  holes  should  be  sluiced  with  water  using  the  same equipment  a  day  before  grouting  as  per  following  sequence;  so  as to saturate the masonry.

All holes are first plugged with proper wooden plugs or locked in the case  of  PVC  nozzles.  The  bottom  most  plug  and  the  two  adjacent plugs  are  removed  and  water  injected  in  the  bottom  most  hole under  pressure.

When  the  clear  water  comes  out  through  the adjacent holes the injection of water is stopped and the plugs in the bottom  most  hole  and  the  one  immediately  above  are  restored.

The  process of grouting of concrete cracks is  repeated  with  other  holes  till  all  the  holes  are covered. On  the  day  of  grouting  all  the  plugs  are  removed  to  drain out excess water and restored before commencing grouting.

The same sequence as described above is adopted for injecting the cement  grout  also.  The  grout  is  kept  fully  stirred/  agitated  under pressure  throughout  the  grouting.

The  grouting  is  carried  out  till refusal  and/  or  till  grout  starts  flowing  from  the  adjacent  hole.  A proper record of the quantity of grout injected into every hole should be maintained.

After grouting, curing should be done for14 days. Tell tales are provided for checking the effectiveness of grouting.

Only such quantities of material for preparing grout should be used, as can be used within 15 minutes of its mixing. Grouting equipment must be cleaned thoroughly after use.

Fig: Grouting Procedure for Concrete Cracks Repair

Precautions during Grouting of Cracks in Concrete :

• During  the  grouting  operation  in  track  or  close  to  it,  speed restrictions  of stop-dead  and  proceed  at  10  kmph  shall  be  imposed at the site of work and same should be continued for a period of 24 hours.
• The restriction  may  then  be  relaxed  to  non-stop  30  kmph  to be  continued  for  a  period  of  another  2-3  days.  However,  speed restrictions indicated above are only guidelines and appropriate  speed restriction at each individual site should be considered.
• Immediately  after  grouting  work,  all  the  grouting  equipment including  the  slurry  and  mixing  drums,  pipes,  nozzles,  etc.  should be  thoroughly  washed  so  that  set  cement  does  not  damage  the equipment.
• After  the  work  has  been  completed,  it  should  be  inspected thoroughly  and  should  be  kept  under observation  for  a  period  of  6  months  to  12  months  for  its  behaviour after  grouting.
• In  case  arch  masonry  of  bridges  is  grouted  to strengthen  the  structure,  some  load  tests  may  be  carried  out  in selected  cases  to  satisfy  that  grouting  has  helped  to  reduce  the deflection  of  crown  and  spread  at  the  springing  to  within permissible limits.