Iron ocher : consequences and management

Source: Régie du bâtiment du Québec

Consequences of the presence of iron ocher?

The iron ocher causes several problems affecting buildings. Indeed, she is: iron ocher.

• Fact appear deposits of sticky mud of ocher color in the catchment of rainwater and in ditches;
• Creates reddish deposits on the concrete slab of basements. These deposits emit odors recalling the sulfur;
• Obstructs agricultural drains: runoff water being no longer channeled far foundations, she seeps into basements, at the junction of foundation walls and slab
• Clogs the valves of anti-refoulement.

Can we eliminate iron ocher or prevent the development of the bacterium?

The iron is present naturally in soil. It is doncocre ferrous and very difficult pipes eliminate it. Same by replacing the soil to the periphery of building, the iron from surrounding soils migrate again towards the drain of the property by natural water runoff.

To prevent the development of the bacterium, should make them disappear from soil the two natural elements that are water and air, what is impossible. It is therefore not conceivable to prevent the chemical reaction that creates the ferrous ocher.

How to prevent ferrous ocher and how to deal with his presence?

Can be prevented iron ocher before or after construction.

Before the construction

The vigilance is required if there are precursors signs like the presence, after a rain, of reddish water in ditches or in surface. During the construction of a property, it is recommended to carry out upon neighbors and of the municipality a background check the sector concerning the risk of ocher training ferrous.

A assessment of current conditions should be carried before proceed with the construction. This evaluation, performed by a professional, will establish:

• Soil type;
• Soil pH;
• Presence of iron or iron bacteria in soil;
• Annual level variation groundwater.

The result of this assessment will the contractor to construct the building avoiding effects of training iron ocher. The adaptations may touch the following elements:

• The level of the concrete slab subsoil, order to situate it above groundwater;
• The choice of agricultural drain (diameter, dimension and locations of openings, composition);
• The location of the geotextile membrane;
• The type of embankment granular.

If the location of the construction remains at risk, it is recommended to develop two chimneys cleaning order to allow cleaning the drain if necessary.

After construction

The vigilance is required if there are precursors signs such as a significant moisture in the basement rate, a recent flood or the presence of reddish water in ditches or surface after a rain.

The possible improvements to existing buildings to mitigate the symptoms of iron ocher patches vary by location. They may require:

• The modification of the slope of the terrain;
• The sealing at the junction of concrete wall and of the concrete slab;
• The installation of Fireplaces cleaning;
• The drainage under the slab;
• The installation of a water repellent coated;
• Laying a membrane sealing;
• The enhancement the basement slab-soil;
• The condemnation of basement.

Example patch proceeding by outside Example patch proceeding by inside.

What are your recourse?

The Régie du bâtiment du Québec (RBQ) recommends to new buyers as well as homebuilders to inform themselves with the municipality to verify if the location of the future house is conducive to formation of iron ocher. The case applicable, preventive measures may be taken.

The RBQ remind you that we can not prevent the training process iron ocher. She recommends owners struggling with this problem to consult a professional or a contractor holding an appropriate license, who may avoid or in minimize the effects.