2.0404.3 Closed Crawl Spaces—Crawl Space Conditioning

Topic: 
Moisture
Subtopic: 
Space Conditioning
Desired Outcome: 
Humidity in closed crawl space Closed crawl space A foundation without wall vents that uses air-sealed walls, ground and foundation moisture control, and mechanical drying methods to control crawl space moisture. Insulation may be located at the conditioned floor level or on the exterior walls. Return pathways are not allowed from the crawl space to the living space is controlled to reduce moisture damage, energy consumption, and pests
TitleSpecification(s)Objective(s)
2.0404.3a
Option 1: dehumidifier

Option 1 may be used in combination with any other specified options

A permanent, low-temperature, auto-restart, minimum ENERGY STARĀ® rated dehumidifier will be installed with a minimum rated capacity of 15 pints per day

Condensate will be drained to daylight or a condensation pump

A return pathway from the crawl space to the living space will not be allowed

Maintain low relative humidity

Reduce conditions conducive to pest activity

Reduce conditions conducive to mold growth and wood rot

Improve IAQ IAQ Indoor air quality in the conditioned space

Improve equipment service life

Save energy in cooling-dominated climates

Improve IAQ IAQ Indoor air quality in the living space

2.0404.3b
Option 2: supply air

Option 2 may be used in combination with any other specified options

Air from a central forced-air conditioning system will be supplied at a rate of 1 cubic foot per minute ( CFM CFM Cubic feet per minute ) per 30 square feet of closed crawl space Closed crawl space A foundation without wall vents that uses air-sealed walls, ground and foundation moisture control, and mechanical drying methods to control crawl space moisture. Insulation may be located at the conditioned floor level or on the exterior walls. Return pathways are not allowed from the crawl space to the living space area

The supply air duct will be fitted with a backflow damper

Maintain low relative humidity

Reduce conditions conducive to pest activity

Reduce conditions conducive to mold growth and wood rot

Improve IAQ IAQ Indoor air quality in the conditioned space

Improve equipment service life

Save energy in cooling-dominated climates

Prevent crawl space air from entering the living space when forced air system is off

2.0404.3c
Option 3: conditioned house air

Option 3 may be used in combination with any other specified options

A continuous-duty, Home Ventilation Institute ( HVI HVI Home Ventilation Institute )-rated, 1-sone or less fan will be installed that supplies 1 CFM CFM Cubic feet per minute of conditioned house air per 50 square feet of closed crawl space Closed crawl space A foundation without wall vents that uses air-sealed walls, ground and foundation moisture control, and mechanical drying methods to control crawl space moisture. Insulation may be located at the conditioned floor level or on the exterior walls. Return pathways are not allowed from the crawl space to the living space area

Optional: An air relief vent to the outside having backdraft protection may be installed

A return pathway from the crawl space to the living space will not be allowed

Maintain low relative humidity

Reduce conditions conducive to pest activity

Reduce conditions conducive to mold growth and wood rot

Improve IAQ IAQ Indoor air quality in the conditioned space

Improve equipment service life

Save energy in cooling-dominated climates

Improve IAQ IAQ Indoor air quality in the living space

2.0404.3d
Option 4: exhaust

A continuous-duty, HVI HVI Home Ventilation Institute -rated, 1 sone or less fan will be installed that exhausts 1 CFM CFM Cubic feet per minute of closed crawl space Closed crawl space A foundation without wall vents that uses air-sealed walls, ground and foundation moisture control, and mechanical drying methods to control crawl space moisture. Insulation may be located at the conditioned floor level or on the exterior walls. Return pathways are not allowed from the crawl space to the living space air per 50 square feet of closed crawl space Closed crawl space A foundation without wall vents that uses air-sealed walls, ground and foundation moisture control, and mechanical drying methods to control crawl space moisture. Insulation may be located at the conditioned floor level or on the exterior walls. Return pathways are not allowed from the crawl space to the living space area

This option will not be installed for exhaust crawl space ventilation if a radon mitigation system is installed or anticipated in the crawl space

Maintain low relative humidity

Reduce conditions conducive to pest activity

Reduce conditions conducive to mold growth and wood rot

Improve IAQ IAQ Indoor air quality in the conditioned space

Improve equipment service life

Save energy in cooling-dominated climates

2.0404.3e
Monitoring alarm system

A durable humidity monitoring system with alarm capability will be installed

A minimum expected service life of 10 years will be ensured

Alert occupant to system failure