What is a Mixed-Humid Climate?
Tuesday, June 15th, 2021 by Sierra Depalma
What is a mixed-humid climate?
At Dritek Solutions, we love our city – Atlanta, GA. Having lived here all our lives and having worked here with the homes and the land for over 30 years, we have become experts about the climate and soils that impact houses and buildings in our beautiful home city.
In Atlanta, GA, and the surrounding areas, we live in what’s called a mixed-humid climate. Homes and buildings in the mixed-humid climate must be able to address solar gains in the summer, medium to high humidity, mild to cold temperatures in the winter, torrential downpours, high winds, and tornadoes, especially in the midwestern and southern states.
A few inches of rain falling on the roof of a house can produce several thousand gallons of water runoff. This runoff must be channeled away from the building foundation to keep the basement or crawlspace dry and to prevent water from seeping into the building interior where it may create moisture problems. If not drained away from the house, the immense volume of water coming off the roof can quickly saturate the soil surrounding the building and wick through the foundation to the interior. Once inside, this moisture can lead to a variety of problems, including mold and rot. Moisture in homes is both a cause of indoor air quality problems and an important factor affecting the durability of the structure.
As a whole-house best practice, it is important to design the house exterior with climate-appropriate flashing, overhangs, gutters, downspouts, and drainage planes to shed rainwater and conduct it away from the house. Gutters and downspouts, as well as foundation waterproofing and drainage solutions, are particularly important to keep water away from the building foundation in areas with expansive soils, such as here in Atlanta, GA and the surrounding areas.
Expansive soils swell when they get wet and can put extreme pressure on foundations, even to the point of causing cracking or uplift of foundation materials. At the very least, when these soils get wet around a building, they can create a trough that collects water, increasing the likelihood of that water seeping into the foundation.
The temperature variations, forces of driving wind and rain, and medium to high humidity levels can take their toll on houses and building. Homes must accommodate significant heating and cooling needs and combat the effects of heavy rain and condensation from humidity, which can degrade structural materials, contribute to mold growth, and cause premature aging.
Here are some recommendations from Building America for homes in the mixed-humid climate:
- Build slab-on-grade foundations and grade lots to drain away from the structure.
- Create a tight thermal envelope and install a positive pressure ventilation system.
- Place the air handler and ducts in conditioned space or go ductless with mini-split heat pumps.
- Plan for storm-water runoff with adequate gutters, flashing, and kick-out diverters. Use pervious paving, vegetation, grading, and swales to handle large storm events.
- Install a dehumidifier to control shoulder-season humidity.
- Install a thermostat with humidity controls.
Because we are experts on the climate and soils that impact houses and buildings in our beautiful city, Atlanta, GA, at Dritek Solutions we can help you with all your foundation waterproofing, repair, and drainage needs.
If you’re interested in getting a firm quote from experienced and trustworthy experts, call us at 1-770-963-9393.