Student Discussion: The 2021 International Residential Code® (IRC®) Exam Study Course

Writing assignment #1
Permits are required any time you want to built, enlarge, alter, repair, move, demo or change the occupancy of a building or structure, or any time you are doing any of the same to any of the building’s systems, if they fall under the code. The specified exemptions include things that aren’t too big, like accessory structures under 200 sq ft, fences under 7 feet, retaining walls not over 4 feet, water tanks under 5,000 gallons and supported at grade. Also exempt are finishing surfaces, like papering, tiling, carpeting, cabinets, countertops, sidewalks and driveways, and some kinds of common play structures like swings and pools not deeper than 24 inches.

Writing assignment #2
Dead load is the weight of all of the materials and components permanently attached to the building. It does not really vary and is pretty easy to calculate. Live load is all of the forces that affect the building sometimes but not always, this includes people, our stuff, and the weather. Live load is temporary, dead load is permanent. A structure must be able strong enough for both.

Writing assignment #3
Where natural lighting is used to illuminate rooms, there must be windows/glazing equal to at least 8% of the floor area of the room. If using artificial light, it must produce illumination equal to 6 candlefoots at a heigh of 30 inches above floor level.

  • At what minimum height is a masonry chimney required to terminate?

A masonry chimney must extend a minimum of 3’ above the highest point at which it penetrates the roof, and no less than 2’ above any portion of the building within 10’.

  • How high above a floor in a garage is an appliance with an ignition source required to be located?

A fuel-fired appliance in a garage shall have the ignition not less than 18" above the floor.

  • What is the maximum permitted length of a clothes dryer exhaust duct? How does the presence of one or more bends affect the allowable length?

The maximum length is 35’, not including the transition duct. Bends shorten the run as outlined in Table 1502.4.6.1, anywhere from 9 inches to 5 feet depending on the size of the duct and the angle of the bend.

  • How far above the highest connected appliance outlet must a natural draft appliance vent terminate? How far above the bottom of a wall vent must a natural draft gas vent terminate?

Natural draft appliances must terminate a minimum of 5’ above the highest connected appliance, and natural draft gas vents must be 12’ above the bottom of a wall vent.

Writing assignment #4
One egress door is required for each dwelling unit, it must be at least 32" inches wide by 78" tall. If all portions of the building cannot access the egress door through a continuous and unobstructed path, not going through a garage, additional egress doors may be necessary.

Writing assignment #5
The sill plate must be bolted to the foundation wall with anchor bolts no smaller than 1/2" in diameter and penetrating at least 7" into the wall. They need to be spaced no further than 6’ apart, within 1’ of each end, but not closer than 7x the diameter of the bolt to the end.

According to the 2021 International Residential Code, the sill plate must be securely anchored to the foundation wall in this manner:
The sill plate must be anchored with bolts that are at least 1/2 inch (12.7 mm) in diameter.
The maximum spacing for anchor bolts is 6 feet on center.
Anchor bolts must be located within 12 inches of the ends of each plate section.