InterNACHI Insulation and Ventilation 3

Question 1

What is the R-value per inch for closed-cell spray polyurethane foam insulation?

Accepted Answer

R-6 to R-7 per inch

Answer

Closed-cell spray polyurethane foam typically provides R-6 to R-7 per inch, the highest R-value per inch among commonly used insulation types.

Question 2

Which condition is most likely to cause 'wind washing' in an attic insulation system?

Accepted Answer

Inadequate soffit vent area compared to ridge vent area

Answer

When ridge vent area exceeds soffit vent area, negative pressure can draw outside air under the insulation at the eaves, degrading its R-value through wind washing.

Question 3

What does the 'net free area' of a vent refer to?

Accepted Answer

The actual open area through which air can pass, excluding frame and screen

Answer

Net free area is the actual unobstructed opening through which air flows, which is always less than the gross vent dimensions due to frames, louvers, and screens.

Question 4

A home inspector observes ice dams on the eaves of a house after a winter storm. Which attic condition most likely contributed to their formation?

Accepted Answer

Heat escaping through inadequate or missing attic insulation warming the roof deck

Answer

Heat escaping from the living space through insufficient attic insulation warms the roof deck, melting snow that refreezes at the cold eaves and forms ice dams.

Question 5

What is the primary function of insulation baffles (rafter vents) installed in attic eave areas?

Accepted Answer

To maintain a clear airway from soffit vents to the attic space above insulation

Answer

Baffles create a channel that keeps soffit vent airflow clear of blown or batt insulation that might otherwise block the eave ventilation pathway.

(InterNACHI) International Association of Certified Home Inspectors Practice Test

(InterNACHI) International Association of Certified Home Inspectors Practice Test

InterNACHI Insulation and Ventilation 3