RMS Building Science & Radon Entry

Question 1

What is the primary pathway through which radon enters most U.S. residential buildings?

Accepted Answer

Through cracks and openings in the foundation and slab

Answer

Through the roof and attic

Answer

Through exterior walls above grade

Answer

Through the electrical wiring system

Question 2

What is the stack effect and how does it relate to radon entry?

Accepted Answer

Warm air rising creates negative pressure at lower levels, drawing in soil gases

Answer

Cold air sinking pushes radon out of the building

Answer

Wind against the building forces radon through windows

Answer

The stack effect only occurs in buildings with chimneys

Question 3

What is the EPA recommended action level for radon in the United States?

Accepted Answer

4 pCi/L (picocuries per liter)

Answer

10 pCi/L

Answer

1 pCi/L

Answer

20 pCi/L

Question 4

What role does soil permeability play in radon mitigation system design?

Accepted Answer

Higher permeability allows better sub-slab communication and more effective depressurization

Answer

Soil permeability has no effect on mitigation design

Answer

Lower permeability always produces better results

Answer

Permeability only matters for crawlspace systems

Question 5

What is a sub-membrane depressurization system?

Accepted Answer

A radon system for crawlspaces using a sealed membrane over soil with suction beneath

Answer

A system that reduces membrane permeability in basement walls

Answer

An underwater dehumidification system

Answer

A type of foundation waterproofing method

Question 6

What is the difference between passive and active radon mitigation systems?

Accepted Answer

Passive relies on natural airflow; active uses a fan to create suction

Answer

They are identical systems

Answer

Active systems don't use electricity

Answer

Passive systems use larger fans