A drywall contractor is installing 5/8-inch drywall on a ceiling with joists 24 inches on center. What is the maximum allowable deflection of the joists to prevent cracking?
Correct Answer
B) L/240
For drywall ceilings, the maximum allowable deflection is typically L/240 to prevent cracking of the drywall and tape joints. This is more restrictive than floor deflection limits due to the brittle nature of drywall.
Why This Is the Correct Answer
L/240 is the correct maximum allowable deflection for drywall ceilings because drywall is a brittle material that cracks easily under structural movement. This deflection limit is specifically established to prevent visible cracking in drywall and tape joints. The L/240 standard applies regardless of joist spacing (16" or 24" O.C.) and is more restrictive than typical floor deflection requirements due to the fragile nature of gypsum board.
Why the Other Options Are Wrong
Option C: L/360
L/180 is still too lenient for drywall ceilings and would not provide adequate protection against cracking of the brittle gypsum board material.
Option D: L/120
L/360 is overly conservative and typically reserved for plastered ceilings or special applications where extremely minimal deflection is required, making it unnecessarily restrictive for standard drywall installations.
Memory Technique
Remember '240 for drywall' - the number 240 sounds like 'dry wall' when you say 'two-forty dry-wall' quickly, helping you associate L/240 with drywall applications.
Reference Hint
Florida Building Code, Chapter 16 - Structural Design, Table 1604.3 for deflection limits, or Chapter 25 - Gypsum Board and Plaster
More Project Mgmt Questions
What is the minimum R-value required for wall insulation in Florida Climate Zone 2?
A subcontractor brings a new chemical product to your jobsite. Under the Globally Harmonized System (GHS), what information must be immediately available to workers?
A construction site has a trench that is 8 feet deep in Type B soil. What is the maximum allowable slope ratio for the trench walls without protective systems?
What is the maximum recommended spacing between drywall screws when attaching to wood studs?
Your crew discovers suspected asbestos-containing materials during a renovation project. What is the first action you should take?
A scaffold platform is 12 feet long and 5 feet wide. If the maximum load capacity is 25 pounds per square foot, what is the total weight capacity of this platform?
Which CSI MasterFormat Division would contain specifications for fire-stopping and firesafing materials?
In tilt-up concrete construction, what is the primary advantage of this method over conventional cast-in-place construction?
Which OSHA standard specifically addresses construction industry safety and health regulations?
A structural drawing shows a beam labeled 'W12x26'. What does the '26' represent?
People Also Study
Business & Financial Management
120 questions · 70% to pass
Contract Administration
60 questions · 70% to pass
Related Study Resources
Previous Question
During a lockout/tagout procedure, an employee discovers that a machine cannot be fully de-energized due to stored energy in hydraulic accumulators. What additional step is required?
Next Question
Which document must be readily available on-site for all hazardous chemicals used in construction?