So instead of moist air being carried out from the crawl space the humid outside air enters the crawlspace and the water condenses out onto the cooler surfaces. During the summer it is a completely different phenomenon.
One of the major debates in the world of crawl spaces these days is how to make use of the vents.
When should crawl space vents be open. Your crawl space vents should always be closed and sealed off from the outside elements. Open vents when over 70 deg F. When the moist air comes into contact with cool crawl space surfaces condensation occurs.
When it comes to crawl space vents open or closed the big debate doesnt want to go away. Many houses come with custom foam blocks that fit into these vents so that they can be blocked or opened. Now most people close their crawl space vents in the wintertime to keep the cold out so that the cold air doesnt freeze the pipes under the house.
Local codes and conventional wisdom requires crawl spaces to be ventilated from the outside to control moisture buildup and reduce damage within the space. During the summer especially during July and August it may be wise to close foundation vents to prevent the muggy air from entering the crawlspace and condensing on cool surfaces especially air conditioner ductwork and associated equipment. A good rule of thumb is to close your crawl space vents once the outside temperature starts dipping down below 40 degrees F.
The Downside of Crawl Space Vents. Closed crawl spaces are consistently better at controlling moisture that enters via the damp earth or from warm humid air that would otherwise infiltrate from the outdoors. So if your crawl space is musty dirty and contaminated with mold so is your home.
Should a crawl space be ventilated. There are a couple of reasons for this with the first being you want to prevent frozen water lines or snow from entering. The prolonged presence of wet air underneath your house can prevent the crawl space from drying out completely which can lead to mold and dry rot.
Homeowners would open their vents to allow fresh outside air to circulate the crawl space and cool their homes. If you close the vents in your crawl space youre actually keeping the dry air out. Even though there is much debate over crawl space vents the general consensus is that they should definitely not be open year round or an even better solution not open at all.
In most cases like in our area in East Tennessee its in the winter. So the idea of venting a crawl space was born. Opening and blocking your vents at the correct times throughout the year can save energy and keep mildew from building up in your foundation.
In the winter when the air is drier and there is less humidity the vents could be closed so that the water and sewage pipes wouldnt freeze. During hot weather the vents would be left open to allow outside air to circulate in the crawl space which would theoretically cool the rest of the house. Spring and fall would be the most ideal times to have your vents open.
In the winter when the air is drier the vents are closed to reduce the chance that the pipes in the crawlspace might freeze. The traditional line of thinking is the vents should be open in the summer and closed in the winter. Venting your crawl space leads to a variety of issues.
The idea for crawl space vents are that they allow fresh air to get in the crawl space to dry out moisture and keep it from getting mold and other problems. More than 50 of the air that flows into your home originates from the crawl. Closed or encapsulated crawl spaces are now preferred to open or vented crawl spaces.
Close vents when under 40 deg F. Numerous studies show crawl space vents are harmful to your home in many ways. However the right answer is very clear.
So our answer is to open and close the vents in your crawlspace seasonally instead of deciding to seal off crawl space vents altogether. A crawl space is an open area in the foundation under the ground floor of a house. Open crawl space vents in summer to keep the crawl space dry.
If you follow our Monthly Maintenance Schedule we recommend the month of October as a good time to do this. In short the answer is generally yes they should be closed up during the winter months. Should crawl space vents be opened or closed Since it is already discussed and agreed on that the dangers of crawl spaces are easily eliminated by proper ventilation that removes moisture contents it now becomes a question of the way and manner to vent the area with maximum impact effect and effects on backfires.
The opportunities for air exchange between June and September are less frequent and far between. First and foremost open vents allow moisture to enter your crawl space. Air Vent makes ones that open at about 70 degrees F close about 40 and dont require any electricity.
The vents at the base of your house are known as foundation or crawl space vents. These spaces are especially prone to mold growth due to high humidity from the air outside but also due to water build-up that evaporates from the ground up. You do not say whether your crawl- space floor is made of dirt or concrete but if it is dirt spread 6-millimeter plastic sheeting over it to help block that source of moisture.
First they let in moisture during hot and humid summer months.