What Architects and Access Specialists Need to Know about Acceptable Construction Tolerances and Dim

1
What Architects and Access Specialists Need to
Know about Acceptable Construction Tolerances and
Dimensional Ranges!

• CA Title 24 Access Codes and ADA Conference March
  1, 2, 2006

2
Maximums and Minimums

• Dimensional ranges, limits and tolerances
• Quantitative minimums
• Proportional ranges
• Conditional ranges
• Ranges in tables, words and graphics
• Minimum expectations

3
What they are Not!

• Design errors and omissions
• Construction errors
• Oops!
• Lack of knowledge of the code or accessibility
  requirements

4
Current ADAAG

• 228 dimensional maximum, minimum or ranges in
  text
• 289 dimensional maximum, minimum or ranges in

5

• Maximums minimums max.s min.s lt,
  gt, lt, gt, - more than greater than within than
  no more than or less less than
  no less than faster than

To up to within within a
not within within at least from
between within a range of not
to exceed shall not exceed not
exceeding nowhere exceed tolerance of
6
CURRENT ADAAG

• 3.2 Dimensional Tolerances.
• All dimensions are subject to conventional
  building industry tolerances for field conditions.

7
New ADA /ABA

• F104.1.1 Construction and manufacturing
  Tolerances.
• All dimensions are subject to conventional
  industry tolerances except where the requirement
  is stated as a range with specific minimum and
  maximum end points.

8
ICC/ANSI A117.1

• 104.2 Dimensions.
• Dimensions that are not stated as maximum or
  minimum are absolute. All dimensions are
  subject to conventional industry tolerances.

(bad language contradictory) (60 maneuvering
space is not stated as maximum or minimum so a
61 clear maneuvering area is wrong?)
9
Minimums and Maximums

• Min.door passage width 32
• For a maximum depth of 24
• Minimum accessible route width
• 36
• Passing width 60 min.

10
Minimums and Maximums

• Bad form dimensions in figures and not in text
  and therefore not readable through alternate
  format materials

11
Minimums and Maximums

• More bad
• forms

Figure 5b Maximum Forward Reach over an
Obstruction The maximum level forward reach over
an obstruction with knee space below is 25 inches
(635 mm). When the obstruction is less than 20
inches (510 mm) deep, the maximum high forward
reach is 48 inches (1220 mm). When the
obstruction projects 20 to 25 inches (510 mm to
635 mm), the maximum high forward reach is 44
inches (1120 mm). (4.2.5, 4.25.3).
12
Minimums and Maximums

• Measured
• to what?

13
Minimums Maximums

• Reach ranges to objects
• Minimum forward reach 15 to 48
• Maximum high side reach 54 (out 10)
• Minimum low side reach 9 (out 10)

14
Minimums Maximums

• Maximum depth reach over obstruction 4
• Maximum height reach over obstruction 46
• Obstruction (cabinet) maximum height 34

15
Most Critical - Functionality

• Wheelchair accessible route clearances
• Maximum reach ranges
• Knee space clearances

16
Most Critical- Physical Safety

• Protruding objects
• Ramp slopes
• Ramp landing size
• Handrails heights
• Curb ramps slopes and flared sides
• Pedestrian barriers (queue lines)

17
Most Critical- Envir. Clues

• Color Contrast
• Lighting Levels
• Visual and Audible Alarms
• Detectable Warnings
• Audible Signals

18
Most Frequent Errors

• Concrete ramp slopes due to slump
• Concrete landing size
• Shimming of casework
• Lavatory height related to floor slope and
  elevation of rim type lavs
• Handrail heights due to floor finishes
• Plumbing rough-in

19
Action Plan

• Reset all standard details to mid-range or an
  additional ½ to 1 inch in on minimum dimensions
• 113 ramps and 122 not ramps
• Lower counter tops and laves to 33
• Lower all non-toilet reach ranges to 48