NHIE Insulation and Ventilation 5

Question 1

An inspector notices that a powered attic ventilator is installed in a tightly sealed home with a natural-draft gas water heater. What hazard should be considered?

Accepted Answer

The fan can depressurize the house through ceiling leaks and cause backdrafting of combustion gases

Answer

If the attic is not sealed from the living space, a powered ventilator can pull conditioned air out of the house and reverse flue draft.

Question 2

Fiberglass batts in an attic have been compressed to half their thickness by stored boxes. How does this affect performance?

Accepted Answer

Total R-value is reduced because the trapped air spaces are lost

Answer

Fiberglass insulates by trapping air, so compressing it lowers its total R-value.

Question 3

Which insulation material typically provides the highest R-value per inch?

Accepted Answer

Closed-cell spray polyurethane foam

Answer

Closed-cell spray foam is roughly R-6 to R-7 per inch, compared with about R-2.5 to R-4 for fiberglass, cellulose, and mineral wool.

Question 4

Exposed spray foam insulation covers the walls of a finished basement recreation room. What should the inspector note?

Accepted Answer

It generally requires a thermal barrier such as 1/2-inch drywall

Answer

Foam plastic insulation in habitable spaces must generally be separated from the interior by an approved thermal barrier such as 1/2-inch gypsum board.

Question 5

In a vented crawlspace with fiberglass batts between the floor joists, which way should the kraft facing face?

Accepted Answer

Up, toward the heated subfloor

Answer

The vapor retarder facing belongs on the warm-in-winter side, which in a crawlspace floor is the subfloor above.

(NHIE) National Home Inspector Examination Practice Test

(NHIE) National Home Inspector Examination Practice Test

NHIE Insulation and Ventilation 5