Crawlspace vent propped open

Would there be a reason a builder would prop the crawlspace vents open with a nail? These vent were inoperable when checked outside- discovered nails barely tapped in when in crawl-

Crawlspace must be vented. Builder ensured the crawl remained vented.


I’m pretty sure there are freezing temps in Idaho, therefore you should be able to close that vent during the winter months.


Scott are you propping up the glass fiber batt to observe the crawlspace window?
Any images further back?

That lever should be able to allow the hatch to open or close. That fastener is an obstruction.

I concur with above. Venting requires the ability to functionally operate within a specific set of rules. Operational Clearances, function and performance.

Awaiting your reply.

There is sufficient clearance to properly operate the vent flap- the builder is suggesting that homeowners fail to open for ventilation in summer so to prevent excess humidity they prop them open-

I inadvertently removed one nail upon inspection and realized the nail’s seemed temporary so did proceed to remove 3 others by hand as I moved throughout the crawl.

The builder is demanding I reinstall the nails to prevent use of vent flap- new construction homebuyer prefers ability to use the flap/damper. They’ll walk through on Monday and I’ll accommodate either if needed since I was wrong for removing the nails.

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That is my information given to clients also about the use of the vents. The builder suggests that the insulation under the floor is installed the vents do but need to be operated in the winter.

I report on systems installed and their function. With the nail installed these vents do not function correctly- defect. They should install vents without dampers in this case unless it’s code to have. I’m not sure on code.

Some builders in Oregon have gone to vents without flaps or remove the flaps. They recommend constant airflow and say the pipes and underfloor are insulated so there’s not need to block vents.

Up until the 1992 code cycle homes (in Oregon anyway) weren’t required to have underfloor insulation and lots had it on the perimeter walls. With those systems it was important to close the vents as nothing under the house was insulated. I often see little notes in the electric panel explaining this. Problem is humans are REALLY poor at doing things when we’re supposed to and these systems just kept the plumbers busy all winter fixing broken pipes.

Every fall I get a few calls and questions so I finally just wrote an article to send people to: Should I Close the Vents to my Crawl Space in the Winter? | Crawford Home Inspections

Very good- thank you Matt, good straightforward article too.

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