What Is That White Powder On My Basement Walls?

Sign of Moisture

The white powder that you see on the surface of the brick or concrete wall is efflorescence. It is a sign of moisture invasion that will lead to great structural damage; and inside air quality issue if you don’t approach it seriously. Although the efflorescence itself is fairly harmless; it’s a sign of awaiting issues. It generally happens in basements with excess moisture. A circumstance that will also encourage the mold and other fungi growth.

Efflorescence is dissolved calcium deposit on the façade of an absorbent material – like brick or concrete; visible after the departure of the water that transported it in the first place. The moisture which causes the efflorescence is often coming from the groundwater. However the excess snowmelt or rainwater can be also the source.

Absorbent Building Materials

The building materials like the wood, concrete, stone and brick; are absorbent materials. They can absorb water by the process which is named capillary action. While this moisture, or even water moves all the way through the absorbent material; the calcium and many other salts will be drawn with it.

Wood, concrete, stone and brick are spongy materials that are full of salts. Capillary action will factually suck water. And carry it through the absorbent building materials; weakening them all the way thru.

Capillary Action

The absorbent building materials are able to carry away the water for large distance; due to the capillary action. For instance, imagine a tree and the way that the tree transports the water from the roots to the leaves. This is capillary action. It is very powerful but at the same time very destructive.

The building materials that are directly in contact with the soil will as expected drive the water inward and upbeat. The water will form a path from below your foundation footing; and continue through the block or concrete walls all thru the wooden structure on top.

Vicious Pressures

In the moment when the capillary stream of water will reach the surface of the building material; evaporation happens. While the water evaporates, the white powder is left following. When this evaporation of the capillary flow will continue for a long period of time; the concentration of the powder will increase. And this is when an imbalance occurs. This process is osmosis. To restore balance through osmosis; the water will rush in the direction of the powdery white deposit in order to reduce its concentration. This water rush creates immense hydrostatic pressure within the absorbent material; and this pressure is destructive.

The osmosis pressure can form extremely strong hydrostatic pressure; that can go over the strength of the building materials. Here we include block and concrete. In other words, an incredible forces are created that can cause the materials to crack and break away from each other.

The painted walls or even the walls that are covered with “waterproofing” materials can be still affected by the capillary action underneath the surface; despite the fact that the actual efflorescence or moisture is not visible. In these circumstances often the paint peels off the walls.

Spalling

In the cases when the efflorescence will lead to tough osmotic pressure; bigger than the strength of the building materials, the material will break apart. The consequential damage is called spalling. The hydrostatic pressure may cause the spalling; but it can also be caused by the freeze-thaw cycle in the building materials that have very high damp content.

How to prevent and get rid of the efflorescence

The efflorescence is normally quite simple to remove with using a wire brush or stiff. But the removing of the surface powder, on the other hand; does not remove the condition that is causing it. So as a rule it returns pretty quickly. The prevention requires complete removal of the source of the moisture; that fuels the capillary action in the building material that is affected.

Do you want to find out what is the cause for efflorescence showing up in your basement? Call the experts at Draintony waterproofing at 416-938-5102 for a free estimation.