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Not Sure of What to Make of Your Crawl Space Ventilation?

Learn how crawl space venting affects the quality of indoor life in your home and what you can do about it.

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For many years, homes across Winston-Salem, NC, were built with vented crawl spaces in total disregard to moisture. Warm and moisture-laden air would flow in, build up, and condense on the crawl space surfaces. In no time, mold would grow, and together with the water, degrade the crawl space. A once dry and clean crawl space would turn into a mess, and the effects would be felt in the living areas above. 

The same thing still happens today. What seems to be holding people back are local codes. Some homeowners would want to close off the vents and look for smarter ways to ventilate their crawl space. Let’s look at what the codes say and the best practices for the space under your home. 

If you’re struggling with the thought of venting your crawl space or wondering how it elevates moisture, this article will provide you with the answers you need. But most importantly, we will show you how to keep moisture under control. 

cover crawl space vents

Origin of Crawl Space Vents 

Crawl space vents have been around for decades. From the 1930s, they were a requirement under local codes. What this meant is homeowners had to fit vents on the outside of their crawl space walls. The HUD urged locals to install vents and leave the ground uncovered. The understanding then was that venting would promote ventilation and curb moisture buildup. 

Unfortunately, these fixtures just did the exact opposite. Fast-forward to today, and things have changed with builders now having the leeway to control moisture. 

Where Do Air Leaks Come From? 

Major culprits include gaps around your water lines and electric wires, ceiling/floor junctions, and wall intersections. The chimney and ducts are other enablers, and so are door, window, and wall sockets in your home. 

Taming Crawl Space Moisture 

Air exchange and expanded polystyrene ground covers have been used for many years to control the crawl space moisture. In addition, builders do recommend these measures: 

  • Resolve negative pressure issues due to air handle fans and other ventilation equipment. 
  • Clear any surface water and install a sump pump
  • Create pathways and seal insulation ducts. 
  • Set the thermostat above the dew point. 
  • Close and seal the vents with vent covers if moisture persists. 
  • Encapsulate and condition the crawl space with a vapor barrier and dehumidifier. 

Is It a Good Idea to Ventilate the Crawl Space? 

The answer is a straight no. Various studies show that venting is counterintuitive. It allows moist air from the outside to saturate the crawl space air. This buildup can lead to condensation on the crawl space walls, mold growth, and wood rot. In addition, excess moisture will damage fiberglass insulation and attract pests. 

A 1985 study showed huge amounts of air moved upward from the crawl space to the living area, bringing with it pollutants, bacteria, and radon. All these can make the indoor air unbreathable. Don’t forget the mustiness that permeates the crawl space atmosphere. 

Your vented crawl space will also rollback the gains you’ve made to cut down utility costs. Buying energy-efficient appliances will mean nothing if you’ll have to run the heater for hours just to warm the home and the crawl space. If you want none of this to happen, seal off the crawl space and condition it. Also, get an energy-efficient crawl space dehumidifier with an air filter to clean up and dry out the air inside. 

Why Sealing the Crawl Space Makes Sense 

Sealing your vented crawl space and conditioning it is beneficial in a number of ways. It will deter condensation and mold/mildew growth. With no cold air coming in, the crawl space will become noticeably warmer. Mustiness, pollutants, bacteria, and mold spores will be a thing of the past. Temperatures won’t swing wildly thanks to the insulation that helps retain heat, lowering your heating costs and reducing the heating hours. 

Controlling moisture and temperatures in a vented crawl space is next to impossible. You will keep fighting moisture, mold, and insects. It’s a battle you will surely lose. If you’d like to know how you seal the crawl space and condition this space, request a free crawl space ventilation inspection and quote from the professionals at Tar Heel Basement Systems. Our experts will assess your crawl space and make recommendations that’ll keep moisture in check. 

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