# Construction Tolerances for Cast-in-Place Concrete Members in a Building

Construction tolerances are allowed variations in a designated dimension of cast-in-place reinforced concrete elements. They are necessary means of controlling vertical element plumb, size, length, and location of various cast-in-place concrete elements in a building. This is because structures are not constructed exactly plumb, level, and straight and such perfection is unnecessary. Nonetheless, tolerances should be established carefully to ensure that they do not influence the strength of the concrete member.

ACI 117M- 10 provides tolerance for cast-in-place concrete members in buildings. Such guidance helps contractors construct cast-in-place buildings satisfactorily, especially in terms of safety, without needing unnecessary and costly perfection.

## Construction Tolerances for Cast-in-Place Concrete Members in a Building

### 1. Deviation from Plumb

The maximum acceptable deviation from the plumb for various cast-in-place concrete members is presented in Table-1. The deviation is the departure from an established point, line, or surface measured perpendicular to the reference line or surface, ACI 117M-10, section 1.3.

Table-1: Deviation from Plumb for Different Cast-in-place Concrete Elements in Buildings

### 2. Horizontal Deviation from Location

The horizontal deviation is the departure from an established point, line, or surface measured normal to a vertical line through the point of interest, ACI 117M-10. Tolerances of horizontal deviation from a location for various concrete members in a building are presented in Table-2.Â

Table-2: Tolerances for Horizontal Deviations from a location for different Concrete Elements in a Building

### 3. Vertical Deviation from Location

A vertical deviation from a location is the departure from an established point, line, or surface measured perpendicular to the horizontal line through the point of interest.Â Â

Table-3: Tolerances for Deviation from Location

### 4. Deviation from Elevation

Table-4 presents tolerances for deviation from elevation for various elements in cast-in-place reinforced concrete elements in a structure.Â

Table-4: Tolerances for Deviation from Elevation

### 5. Deviation from Cross-sectional Dimensions

Tolerances for deviation from cross-sectional dimension for different concrete members can be found in Table-5.

Table-5: Tolerances for Deviations from Cross-sectional Dimensions

### 6. Deviations from Formed Opening Width or Height

The deviation from formed opening width or height falls between -13 mm and +25 mm.

1. Deviation from Relative Elevations or Widths for Stairs
• The difference between the largest and smallest tread or riser in any flight shall not exceed 10 mm.
• The difference in the height of adjacent risers measured at the nose shall not exceed 5 mm.
• The difference in depth of adjacent treads shall not exceed 5 mm.
• Stair tread from back to nosing is Â±6 mm

## FAQs

What is construction tolerance?

Construction tolerances are allowed variations in a designated dimension of cast-in-place reinforced concrete elements. They are necessary means of controlling vertical element plumb, size, length, and location of various cast-in-place concrete elements in a building

Why is construction tolerance important?

1. Set up the ease of construction without the necessity for later modifications and changes.
2. Ensure the structure performs satisfactorily, especially in terms of safety.
3. Avoid unnecessary and expensive accuracy and perfection.

What is the horizontal deviation?

The horizontal deviation is the departure from an established point, line, or surface measured normal to a vertical line through the point of interest, ACI 117M-10.

What is the vertical deviation?

A vertical deviation is a departure from an established point, line, or surface measured perpendicular to the horizontal line through the point of interest.Â

What is the maximum acceptable vertical deviation from a location for walls and columns?

The maximum acceptable vertical deviation from a location for walls and columns is Â±25 mm