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Crawlspace dehumidifier 101

Posted Mar 31, 2021 in Waterproofing

Crawl­spaces are noto­ri­ous­ly damp, but they shouldn’t be. Mois­ture can dam­age the sup­port­ing struc­ture and lead to dan­ger­ous mold growth that can affect your health. A dehu­mid­i­fi­er is one of the best options for keep­ing humid­i­ty and mois­ture under con­trol, but there are a few draw­backs to installing one in your crawlspace.

Leaks, drips and puddles

A dehu­mid­i­fi­er will not cor­rect pud­dles and water leak­ing or drip­ping into the crawl space. Before try­ing to tack­le the mois­ture in the air, you need to locate the source of the water and stop the leak. It may be nec­es­sary to adjust the angle of any vents, add a lin­ing to the crawl space or seal any holes.

The fuzzy stuff

A dehu­mid­i­fi­er can pre­vent mold and mildew, but it won’t remove it once it is estab­lished in your crawl space. In fact, a dehu­mid­i­fi­er can spread mold spores through­out the space and even push them into your home. Like stand­ing water and leaks, you should remove mold and mildew before plac­ing a dehu­mid­i­fi­er in the crawl space.

It’s all relative

Vent­ing is fre­quent­ly tout­ed as a solu­tion to excess mois­ture in a crawl­space. While open­ing the vents, or installing addi­tion­al ones, can improve air cir­cu­la­tion, mois­ture will not dis­si­pate if the out­side air is not dri­er than the crawl space air. In areas with high humid­i­ty, it may be impos­si­ble for mois­ture to leave the crawl space through vents, and mechan­i­cal removal with a dehu­mid­i­fi­er may be the only choice.

Dry it up

A dehu­mid­i­fi­er is effec­tive in con­trol­ling mois­ture in your crawl­space but uses elec­tric­i­ty to do so, which can dri­ve up your elec­tric­i­ty bill. You must also keep it repaired and main­tained. Some dehu­mid­i­fiers also require elec­tric fans placed through­out the crawl space to help move the air, adding to the elec­tric­i­ty and main­te­nance costs. Water col­lect­ed by the unit must be prop­er­ly drained away. If not, it can flood the crawl space. On the oth­er hand, if you do not remove the excess mois­ture, it can dete­ri­o­rate wood fram­ing and rust met­al com­po­nents in the crawl space, and encour­age the growth of dan­ger­ous mold and mildew.

Oth­er options

Installing addi­tion­al insu­la­tion can reduce the for­ma­tion of mois­ture due to tem­per­a­ture dif­fer­ences, while addi­tion­al vents can increase air cir­cu­la­tion. You can open exist­ing vents wider, or leave them open year-round to reduce mois­ture. You can also install a spe­cial lin­er that cre­ates a bar­ri­er between the earth and the crawl space and seals out com­mon sources of moisture.