ASHI ASHI Foundations & Basements 2 — Questions and Answers
Question 1: What is the minimum headroom required in a basement by most US model building codes (IRC)?
- 6 feet 8 inches (2032 mm) (Correct answer)
- 7 feet 0 inches (2134 mm)
- 6 feet 0 inches (1829 mm)
- 7 feet 6 inches (2286 mm)
Correct answer: 6 feet 8 inches (2032 mm)
The IRC requires a minimum ceiling height of 6 feet 8 inches in habitable basement spaces, with beams permitted to project lower.
Question 2: During a crawl space inspection, an ASHI inspector finds standing water. This should be reported because:
- Standing water promotes wood rot, mold growth, and deterioration of structural components (Correct answer)
- It indicates the lot grading complies with drainage requirements
- Standing water is expected in unconditioned crawl spaces
- It only affects the vapor retarder, not structural elements
Correct answer: Standing water promotes wood rot, mold growth, and deterioration of structural components
Standing water in a crawl space creates conditions for fungal growth and wood decay, directly threatening floor framing and other structural components.
Question 3: A crawl space vapor retarder should cover:
- At least the exposed soil of the crawl space floor, lapped and sealed at seams (Correct answer)
- Only the areas directly under plumbing lines
- The interior face of the foundation walls only
- The underside of the floor joists
Correct answer: At least the exposed soil of the crawl space floor, lapped and sealed at seams
The vapor retarder must cover the exposed soil to block ground moisture from evaporating into the crawl space and wetting structural wood.
Question 4: Pyrite (iron sulfide) inclusions in fill used beneath a concrete slab can cause:
- Swelling and heaving of the slab as the pyrite oxidizes and expands (Correct answer)
- Accelerated carbonation of the concrete surface
- Increased radon gas emission through the slab
- Corrosion of steel reinforcement near the surface
Correct answer: Swelling and heaving of the slab as the pyrite oxidizes and expands
When pyrite oxidizes in the presence of water and oxygen, it expands significantly, creating upward pressure that heaves and cracks concrete slabs.
Question 5: What does an ASHI inspector look for when evaluating foundation settlement?
- Cracks, displacement, out-of-plumb walls, sticking doors, and sloped floors (Correct answer)
- Only vertical cracks wider than 1/4 inch
- Evidence of previous waterproofing attempts
- The type of soil visible at the exterior grade
Correct answer: Cracks, displacement, out-of-plumb walls, sticking doors, and sloped floors
Settlement manifests as a pattern of related symptoms throughout the structure, including cracks, door and window binding, and floor slope.
Question 6: Which foundation type is most susceptible to lateral soil pressure causing wall failure?
- Hollow concrete masonry unit (CMU/block) wall (Correct answer)
- Poured concrete wall
- Insulated concrete form (ICF) wall
- Treated wood foundation
Correct answer: Hollow concrete masonry unit (CMU/block) wall
Hollow CMU walls have lower bending resistance than solid poured concrete, making them more vulnerable to cracking and bowing under lateral soil pressure.
ASHI ASHI Foundations & Basements 2
What is the minimum headroom required in a basement by most US model building codes (IRC)?