Inspection Training

How to Inspect the Crawl Space Ventilation

While the inspector is in the crawl space and while they are at the exterior they should be able to see any passive crawl space vents. You can take a picture from the inside or the outside of the crawl space. Please review the entire procedure below.


International Standards of Practice for Performing a General Home Inspection


3.9. Attic, Insulation & Ventilation


I. The inspector shall inspect:

B. Ventilation of unfinished spaces, including attics, crawlspaces and foundation areas.


II. The inspector shall describe:



III. The inspector shall report as in need of correction:

A. The general absence of insulation or ventilation in unfinished spaces.


IV. The inspector is not required to:

A. Enter any unfinished spaces that are not readily accessible, or where entry could cause damage or, in the inspector’s opinion, pose a safety hazard.
F. Operate thermostatically operated fans.
H. Determine the adequacy of ventilation.


Axium SOP Differences

Axium Requires: Same as NACHI Standards of Practice.


Tools Needed

No tools required to inspect the Crawlspace Ventilation.



  • While inspecting the crawlspace we will want to check for proper ventilation of the crawlspace. There is one picture required for this section and it should show the ventilation in the crawlspace. If there is a thermostat operated ventilation fan we will want to take a picture of that control.

Common Defects

  • There are no defects for this section.


Common Mistakes

  • Not checking the crawlspace for ventilation.
  • Not taking a picture of the thermostat controlled ventilation fan.


Report / Software


  • Passive Vents: The crawl space was equipped with operable vents which should be closed during cold weather to prevent pipes in the crawl space from freezing and to save on heating costs. Vents should be opened during warm weather to allow natural air movement to carry away moisture.
  • Active Vent Fan: The crawl space was equipped with an active ventilation fan that appeared to be installed properly and was operating at time of inspection.


  • N/A


  • The best approach to venting crawl spaces has recently been the subject of controversy. It is generally agreed that a ventilation design which works well in one climate may perform poorly in another. The inspector recommends that the crawl space should be ventilated according to recommendations for the climate zone in which the property is located.


  • N/A