Waterproofing and French drain installation / Iron Ochre

The symptoms of inadequate soil drainage

The current symptoms of inadequate soil drainage near the foundation walls may be manifested by:

• The presence of a white powder named efflorescence
• The presence of mildew at the bottom of the interior walls in the basement
• The presence of moisture and a perpetually-damp cement wall and floor in the basement

The causes

Lack of drainage - In buildings constructed before 1950, we often notice that there is a lack of a drain around the footing. In such cases, if it rains for too long or too heavily, or when the snow melts, hydrostatic pressure can build up on the foundation and cause problems by having water leaks and damaged concrete.

Deficient drain - Drains that have been installed for more than 25 years are often blocked by sand or fine soil particulate accumulated over the years. Whether the drain is made of plastic or baked clay, it could also be broken, displaced or crushed, resulting in its malfunction.

Presence of iron ochre - In this case, the gelatinous rust-coloured mud adheres around the drain and prevents water from evacuating thereby causing water infiltration. This problem is often combined with the water table being too high in comparison to the basement level.

Solution to waterproof the foundation using a membrane and a french drain.

Excavation - We first excavate the work areas using the appropriate equipment in such a way as to cause the least inconvenience possible.

Waterproofing - After cleaning the foundation, special care is focused on cracks and an elastomeric membrane is sprayed on the underground section of the foundation walls thereby assuring a good waterproofing.

Drainage - In order to protect the membrane at the time of the backfill and to accelerate the drainage we (could may or might) install an insulation panel under the ground level that will also insulate the foundation. Finally, we install the french drain at the bottom of the foundation walls and cover it with crushed stone.

Solution against the presence of iron ochre

Waterproof lining - The only guaranteed solution in the case of iron ochre is to install a waterproof lining on the outside walls of the foundation as well as under the concrete slab, which then becomes a waterproof casing, thus blocking water drainage towards the foundation. Raising the property is often required.