Winter Tip: Foundation Vents--To Block, Or Not?

Home Inspector with NICKELSEN HOME INSPECTIONS - Vancouver WA Home Inspector

We are coming off of the summer, our driest time of the year, and this year's dry period was also marked by the longest streak of no rain in the (recorded) history of SW Washington and NW Oregon (don't you miss it already?). As we move into the colder season a lot of people will be moved to buy and/or install foam foundation vent blocks to "keep the cold air out of the crawl space", a reasonable idea, but one that we don't recommend in most cases. The vents around your foundation (assuming that you have a home with a crawl space) are intended to allow your crawl space to breath. Your reasonable idea is that if you block the crawl space you will be keeping the cold air out from under the home, thus keeping pipes from freezing and keeping the floors warmer--i.e., you are attempting to be energy efficient. In this area of the country our winters are marked less by cold air and snow than they are by rain, and lots of it! That rain gets the soils wet, which, in most homes, leads to moist grounds under the home. You want that moisture to go out of the crawl space and you want the crawl space to breath, which is what the foundation vents are for. As such, while a reasonable idea (i.e., to block the vents), one is actually "choking" the crawl space, keeping it from breathing and ejecting that moisture (to the extent that it can) via the foundation vents. So, in principal, we strongly recommend that you keep your foundation vents unblocked year round, especially (ironically) in the winter. Now to the exceptions. Let's say that you have an older home in the area. Say it is from the 1920s through the 1960's and your crawl space has no insulation on the piping and no insulation under the main level floor (what would be above you if you were crawling under the home). Now, let's also say that you have a "dusty dry" crawl space (which is somewhat common in this area on older ranch style homes in this area). If THAT is the case, then you might consider installing foundation vent blocks. But I would only consider it if you had that senario: 1) dry crawl space year round (i.e., the dirty is "dusty dry"); 2) you have no insulation and/or have no insulation on the piping). Ideally you would consider adding insulation to both the floor and the piping, but that we will save for another post. Have a great week and a Happy Halloween! - **** Nickelsen Home Inspections, LLC |360.907.9648 | Like our Facebook Page |

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Nickelsen Home Inspection

If you or anyone you know is in need of professional home inspection services and structural pest inspection/pest and dry rot inspection services in NW Oregon or SW Washington, please consider referring them to us.  We cover the Gorge to the Coast, and Salem to Olympia, including Vancouver and Portland and much more.  

p. 503.502.1495 | cell/text 360.907.9648


Justin Nickelsen, CMI

Nickelsen Home Inspections, LLC

"A Conduit for Educated Real Estate Transactions"

Serving Oregon and Washington From the Mountains to the Coast

Professional Licenses, Memberships and Certificates

  • Certified Master Inspector (CMI) with the Master Inspector Certification Board
  • The American Society of Home Inspectors - ASHI Certified Inspector and Member #246145
  • The National Association of Home Inspectors - NAHI Member
  • The International Association of Certified Home Inspectors - InterNACHI #0073170
  • IAC2 Certified Indoor Air Consultant - IAC2-01-0235
  • Vice President of theOregonChapter of InterNACHI
  • Founding Member of SWWAHI - TheSW WashingtonAssociation of Home Inspectors
  • OregonLicensed Home Inspection Firm CCB# 172294
  • OregonCertified Home Inspector OCHI# 1173
  • WashingtonStateLicensed Home Inspector #415
  • Licensed and Certified StructuralPestInspector through the Washington State Department of Agriculture (71352)
  • Member of theWashingtonStatePestManagement Association
  • Passed the National Home Inspectors Examination
  • Second Generation Inspector
  • Annually Performing 450-550 Inspections/Thousands Performed in Career
  • Past Experience as a Contractor - All Phases of Residential Construction
  • Annually Maintaining Over 50 Hours of Continuing Education (twice the requirements of OR and WA)
  • Past Member of OAHI - TheOregonAssociation of Home Inspectors
  • Past Member of NWOCHI - The NWOregonAssociation of Certified Home Inspectors
  • Past Member of OREIA - TheOregonReal Estate Inspection Association
  • Specializations: Electronic Radon Measurement, Early 20th Century Properties, Early 1990's Properties, New Construction, Log Homes, Structural Pest Inspections (Termites/Carpenter Ants).
  • Advanced Skills: Oral and Written Communication, Advanced Reporting and Detailed Analysis.

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