Tolerance limits in construction work on site

Tolerances in construction are generally a variation in a dimension, construction limit, or physical char- acteristic of a material. They are a practical variation related to the function of the material or finished work and commonly accepted standards of the construction industry.

 In construction all work outside these limits is liable to rejection. The following table gives permissible deviations in the tolerances on construction

Shuttering

	Description	Permissible Deviation
	Deviation from specified dimensions of cross section of columns and beams	-6 mm +12 mm
	Deviation from dimensions of footings
	Dimensions in plan	-12 mm +50 mm
2.	Eccentricity	0.02 times the width of the footing in the direction of deviation but not more than 50 mm
3.	Thickness	+0.05 times the specified thickness
	Departure from level shown on the drawing	6 mm
	Deviations Abrupt irregularities/offsets caused by displaced or misplaced form work lining or supports	3 mm
	Inserts Variations in the position along concrete surfaces In plane position (flush with concrete face)	10mm 6 mm

Note:

• These tolerances apply to concrete dimensions only, not to positioning of vertical reinforcing steel or dowels.
• The formwork shall be capable of being dismantled and removed from the cast concrete without shock, disturbance or damage.
• The arrangement shall be such that the soffit forms are properly supported on props, can be retained in position for such period as may be required by maturing conditions or specifications.

Measuring equipment accuracy in Batching plant.

• Cement : + – 2%
• Aggregate : + – 3%
• Admixture : + – 3%
• Water : + – 3%
• Mixing time : 2 minutes for one mixing. (Mixing which is being done on site)

Tolerance for cutting Length

•  When Specified length is not given = + 75 mm (or) – 25 mm
• When minimum length is specified = + 50 mm (or) – 0 mm