(September 18, 2003) Fab-Form Industries conducted a simple test to measure the quantity of water wicked up through a concrete column.

The test was carried out under the supervision of Phoenix Engineering Ltd., a leading Geotechnical Engineering Firm specializing in the movement of water in soil structures.

Testing Apparatus
A column of concrete 5-1/2" in diameter and 28" in height was set on end in a 5 gallon plastic bucket filled with 7-1/2" of water (about 10-1/2" after installing the concrete). To prevent the evaporation of water from the bucket itself, the top of the bucket around the column was sealed with a sheet of polyethylene plastic.

After allowing five days for the water to wick up the column, the bucket was weighed each morning for 2 weeks to measure the quantity of water wicked up through the concrete and evaporated into the air above. The test took place in early September - air conditions were warm and dry. The bucket was set on a desk, exposed to reasonable ventilation with no direct sunlight.

Results
As can be seen from the graph, the weight on the first day of measurement, August 26th, was 77.6 lbs. Thirteen days later, September 8th, the weight had dropped to 70.6 lbs., a total loss of 7.0 pounds, which equals 7.0/13, or .54 pounds per day of wicking and evaporation.

The cross sectional area of the 5-1/2" column was .16 square feet. Therefore one square foot of concrete wicks up .54/.16 or 3.38 pounds of water per day.

How Much Water Can a Foundation Wick?

A typical basement has approximately 200 lineal feet of wall, 8" thick, hence a cross sectional area of 133 square feet (200' x 8"/12"). The foundation concrete has the capacity to wick at least 435 pounds of water each day (3.38 x 133) under similar conditions to the test. As 435 pounds of water is equivalent to ten 5-gallon buckets of water each day, it is evident that rising damp can be a major contributor to moisture and mold in basement foundations.

Would a typical basement wick this quantity of water? Only if there was water ponding surrounding the footing (which occurs with impervious soils not correctly drained), and where the interior walls were openly exposed to dry interior air. In most basements, the quantity of water wicked through the foundation would be considerably less. Mold growth, however, requires a slow and persistent moisture source, which is exactly what rising damp is good at providing.

Conclusions

1. Rising damp can be a major contributor to dampness and molds in basements.

2. ALL concrete in contact with moisture laden soils must be protected from moisture by a membrane (or other appropriate method).

3. Maximum moisture levels surrounding a basement are typically found at the bottom of the excavation where the concrete footing is located.

4. Concrete footings must be protected from ground moisture.

5. The Fastfoot® membrane is a cost effective method of preventing rising damp in concrete footings.

For a printable report on rising damp, please click here.