Should my crawl space be cold in the summer?

Asked By: Hossein Lindmeyr | Last Updated: 7th April, 2020
Category: home and garden indoor environmental quality
4.5/5 (232 Views . 35 Votes)
The source of the cold is the earth and the source of the warmth is the air coming from your vents, so the surfaces of your crawl space are always colder than the air in a crawl space. So on this summer day, we get condensation, which means the crawl space walls get wet.

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Also to know is, what temperature should a crawl space be?

Your crawl space is 66 degrees, but the surface temperature of your walls, dirt floor and floor joists is 62 degrees. What will happen when this air comes in? We said that for every one degree we cool the air, the relative humidity goes up by 2.2%, because cool air holds less water than warm air.

One may also ask, should crawl space vents be open in the summer? ✅Vote: open and close crawlspace vents seasonally Building codes generally require working vents in the crawlspace to allow outside air to circulate under the floor in the summer to prevent moisture buildup that, among mildew and mold, encourages wood rot.

In this manner, why is my crawl space so cold?

The cause of cold floors above the crawl space is air flow. The crawl space insulation you have under the floor isn't enough to prevent the floor above from cooling down, and the colder temperatures force your heating system to work harder, costing you money.

Should a crawl space be heated?

That's because the insulation may actually prevent heat loss through the floor, making the crawlspace even colder, which is the source of the cold floor in the first place. Once complete, adding heat to the crawlspace area will warm it and allow warm air to rise naturally into the living space above.

39 Related Question Answers Found

Why is my crawl space cold in the summer?

The source of the cold is the earth and the source of the warmth is the air coming from your vents, so the surfaces of your crawl space are always colder than the air in a crawl space. So on this summer day, we get condensation, which means the crawl space walls get wet. The cold water pipes become wet.

What is acceptable moisture level in crawl space?

With an RH of 10% and normal temperatures, you can expect wood moisture content to be around 3%. With a relative humidity of 100%, you can expect a wood moisture content of 23 to 26%. The 28% wood moisture content necessary for rot to occur doesn't come about from just high humidity.

Why is my crawl space so humid?

Condensation is an indication that the air within your crawl space has reached 100% relative humidity. The air can no longer hold the moisture and it's condensing on the surfaces in the vicinity. This causes the organic materials that make up your crawl space to become damp, inviting toxic mold to set up shop.

At what temperature do pipes freeze in crawl space?

Water freezes at 32 degrees Fahrenheit, but indoor pipes are somewhat protected from outdoor temperature extremes, even in unheated areas of the house like in the attic or garage. Just because it's 32 degrees outside doesn't mean the pipes will reach those temperatures.

Is insulating crawl space worth it?


Properly installed insulation will provide the following benefits. If the rooms above your crawl space often feel warmer or colder than the rest of the house, the crawl space is the likely offender. Insulating the crawl space will lead to fewer drafts and cold spots in the rooms above, as temperature is regulated.

How do I make my crawl space warmer?

One way to deal with a cold crawl space is to make it part of the warm side of your house. You'll need to close off the venting, insulate your foundation walls, and supply some heat to the space. A heating duct and cold-air return will balance out the air exchange to and from the crawl space.

Can I use a regular dehumidifier in a crawl space?

A dehumidifier can prevent mold and mildew, but it won't remove it once it is established in your crawl space. Like standing water and leaks, you should remove mold and mildew before placing a dehumidifier in the crawl space.

How do you insulate a crawl space with a dirt floor?

Seal the crawl space vents so that moist exterior air can't get into the crawl space. If the crawl space has a dirt floor, seal that with a thick plastic vapor barrier. Install rigid foam insulation against crawl space walls, so that we're insulating the crawl space instead of the first floor.

What is the best way to insulate a crawl space with a dirt floor?

Cover the walls with insulation from the sill plate to the plastic covered dirt floor. The sill plate is the first piece of framing lumber, and it runs on top of the crawl space wall. When you're using fiberglass batting insulation material, run it about 6 inches or so onto the crawl space floor.

What should I put on my crawl space floor?


Add a vapor barrier: Whether the floor of your crawl space is bare earth, gravel, or concrete, it is going to exude moisture. A 6-mil polyethylene plastic vapor barrier covering the ground keeps the wet at bay. Get rid of moisture: Moist household air is bound to cause condensation in the crawl space.

Should you insulate a crawl space ceiling?

Fiberglass insulation on the floor joists in a crawl space will help keep the floor above warm. However, in a moist, ventilated crawl space, this insulation will eventually rot and become soaked with moisture. This will cause it to fall off the ceiling and on to the floor.

Should you insulate floor above crawl space?

If the crawl space is ventilated, which is ideal because it aids in the elimination of moisture, then fiberglass insulation can be easily installed under the subfloor between the floor joists. If your crawl space isn't ventilated, insulate the walls of the crawl space rather than the subfloor of the room above.

How do you keep water pipes from freezing in a crawl space?

If your kitchen sink is near an outside wall, you can keep the cupboard under the sink open. This allows heat from the house to the pipes which will help prevent freezing. Use foam board in your crawl space along the edges. Screw it into the frame on the inside of your crawl space.

Can you use spray foam insulation in crawl space?

Because closed-cell foam is resistant to moisture and rodent activity, many well-intentioned handymen and homeowners have started to use it as an insulation material in basements and crawl spaces. Don't get me wrong, spray foam, when used in moderation to seal gaps, can be effective.

What kind of insulation do you use in a crawl space?


The best insulation material for crawl spaces is rigid foam insulation board. Instead of installing the foam insulation between floor joists in the crawl space, the foam board is installed against the crawl space foundation walls.

How do you ventilate a crawl space?

The tried and false method of venting the crawl space to the outdoors. Putting a little bit of supply air from the HVAC system into the crawl space.

Let's take a look at each of these methods.
  1. Vent the crawl space to the outside.
  2. Supply air from the HVAC system.
  3. Exhaust air to the outside.
  4. Install a dehumidifier.

Should a crawl space be ventilated?

If, however, you cover the bare ground in your crawlspace with an approved vapor barrier material, you only need 1 square foot of vent for every 1,500 square feet of space. The Code also requires that there be one ventilated opening near each corner of the building. This is necessary to ensure good cross-flow of air.