Atlanta Mold LLC News and Information
Exterior rain water runoff against a foundation is the primary cause of moisture in crawl spaces and basements. This is true whether a concrete block or poured concrete foundation.
The problem arises when runoff from rain is allowed to saturate the ground next to a foundation. This is usually caused by ground settling over time. When foundations are constructed, loose fill dirt is placed next to the foundation excavation. Because it is loose, mechanically compacting it is the standard of practice. However the soil will eventually shrink lowering the finish grade. Home gutters and rain water runoff then has easy access to the foundation.
The solution is to make sure all rain runoff is directed away from the home. This can be done by extending the downspouts from the gutters and adding soil next to the house to raise the final grade.
Moisture in block foundation behind finish wall
Results in wetting the finish wall surface
A common finding when foundation is below exterior grade
Note the white efflorescence
Moisture intrusion into an unconditioned living space results in elevated relative humidity.
Sustained humidity above 70% creates an environment for mold to germinate
Rain water run-off actively penetrating block foundation wall.
Exterior landscape grade must allow rain water
run-off to flow away from foundation - Always
Exterior landscaping must slope 1/2 inch per foot away from foundation
Crawl Space Block Foundation
Moisture through foundation allows mold growth
Damage occurs to foundation and support structures
Serious foundation water intrusion
Rain water run-off from exterior penetrates the foundation - Destructive
Entire foundation displays efflorescence and moisture penetration
A close look at floor joists shows extensive mold amplification
To identify possible moisture intrusion around your home, carefully inspect the perimeter of your foundation. Look for areas where the earth ground looks to have settled next to the foundation. Landscaping by planting trees and bushes next to the house usually results in a loose and permeable soil. Overtime this loose soil will settle resulting a downward slope towards the house.This allows rain water runoff to saturate the soil hence the foundation.