Foundation & Structural Systems Flashcards

What is the primary purpose of installing perforated drain tile (drainage pipe) around the perimeter of a residential foundation?

Answer: To collect and redirect groundwater away from the foundation before it can penetrate

Perforated drain tile collects groundwater around the foundation and channels it to a sump pit or daylight outlet, reducing hydrostatic pressure against foundation walls.

What is the difference between 'dampproofing' and 'waterproofing' a residential foundation wall?

Answer: Dampproofing resists soil moisture vapor only, while waterproofing resists liquid water under hydrostatic pressure

Dampproofing (typically asphalt-based coating) resists moisture vapor transmission only, while waterproofing membranes are engineered to resist liquid water under hydrostatic pressure in high water-table conditions.

Which symptom is most characteristic of differential settlement in a residential structure?

Answer: Diagonal stair-step cracks at the corners of windows and door frames

Differential settlement causes one part of the structure to drop more than another, placing the rigid wall assemblies in shear stress and producing diagonal cracks that typically radiate from the corners of openings.

Per the IRC, what is the minimum required height that the top of a foundation wall must extend above the finished grade adjacent to the wall?

Answer: 6 inches

IRC Section R317.1 (and related provisions) requires the top of the foundation to be a minimum of 6 inches above the finished grade to protect wood sill plates from soil and splash-back moisture.

What is the purpose of a capillary break (such as sill gasket or roofing felt) installed between a concrete foundation wall and a wood sill plate?

Answer: To prevent moisture from wicking upward through the concrete into the wood framing

Concrete is porous and can wick moisture upward by capillary action; a capillary break interrupts this moisture path before it reaches the wood sill plate, preventing rot and decay.

Which condition most urgently indicates an active foundation drainage failure requiring immediate remediation?

Answer: Active water flowing through cracks in the foundation wall during rain events

Active water infiltration through foundation cracks during rain events indicates that hydrostatic pressure is currently exceeding the wall's resistance, posing immediate risk of structural damage and mold growth.

What is the primary structural reason for installing steel reinforcing bars (rebar) in residential concrete foundation walls and footings?

Answer: To increase the tensile strength of concrete, which is weak in tension, preventing cracking under load

Concrete is strong in compression but weak in tension; steel rebar carries tensile forces caused by bending, soil pressure, and settlement loads, preventing cracking and structural failure.