This is the most common of all foundation leaks because it is so easily overlooked at the phase of the foundation construction. Whether you’re dealing with a leak on a new foundation or a callback on a previously completed project, it can be very frustrating trying to determine the cause of the problem. Most generally, a cold joint won’t show signs of water intrusion until two or three years after the job has been completed. The reason for this is because it often takes time for the final grade to settle around the foundation where the earth was disturbed. This area around the foundation that’s prone to settlement over time is generally referred to as the overcut. The overcut usually extends 3'-5' in most cases beyond the foundation wall and is created during the excavation process to provide the concrete contractor ample space to form the footings, stand the wall forms and apply a foundation coating. Depending on which type of material is being used to backfill the foundation walls, it basically breaks down into two categories. Select granular material (bank run sand) is the preferred choice and is often imported for backfilling, but sometimes onsite materials are quite suitable if they are found to be well-draining in nature. Well graded, bank run sand provides excellent drainage and good compaction. The other type of backfill material that is most commonly used is the unclassified blend of soils that are generated during the excavation of the foundation. It’s difficult to predict how well unclassified materials will drain storm water if the soil make up contains silt and clay-like properties. Equally important is the fact that good compaction rates cannot be achieved with clay-type soils that are commonly found here on the east end. How all of this comes into the big picture of the overcut and soil settlement is that granular materials have a tendency to compact faster naturally during the timeline of the project. For example, a project that is started during a hot, dry summer and is backfilled with imported select granular materials will experience less settlement overall than that of the same job backfilled with a silty unclassified soil. The reason for this is because if the onsite material is backfilled and it is dry and powdery in texture it won’t begin to compact until after water/moisture is introduced. If the soil has a high silt content or a clay type commonly encountered in the first few feet of excavation, it will tend to “mud up” when water comes in contact. This is a slow process of water/moisture migrating into dry soils and it can take a long time for the soil to settle out; in most cases it’s not until after several cold winters that the ground around the overcut compacts. This soil in the overcut is what dictates the overall life expectancy of a foundation wall. For example, most foundation footings are constructed in granular undisturbed soil, so backfilling with a well-graded bank run sand will promote good drainage. **However, as this photo illustrates, silt, clay and foundation coatings are covering the granular material at the footing level as a result of storm water runoff into the overcut area of the excavation. This condition if left uncorrected prior to backfill poses a huge problem if the area of the overcut is backfilled with well-graded bank run sand. The well-draining backfill material will absorb and deposit a large volume of water above this layer of sediment. This perched water can now migrate into the foundation wall by the path of least resistance, a cold joint, crack or utility penetration, producing water on the inside surfaces. Trapped subsurface water in heavy unclassified soils can produce the same effects with the difference being unpredictable points of entry.
New Home Construction backfilled with unclassified fill material over a granular base.
30 year waterproofing system voided due to inadequately functioning exterior footing drain..
Perched water at the footing level due to silt,
sediment and foundation coating settling
at the base of the excavation.
Cold joints come in several forms. One type is quite simply: when the foundation pour cannot be completed in a single day and may require several days or even weeks to accomplish depending on the size of the project. Additions to an existing foundation are another type of cold joint where a similar material or completely different material such CMU block to poured concrete are butted together. Since old concrete and new concrete do not bond together homogeneously and do not form a monolithic concrete body, stress cracks concentrate mainly in these areas. The cold joint that almost every foundation shares regardless the type of construction, whether it is poured concrete, CMU block, brick or stone, is the joint between the footing and the wall itself. For all types of cold joint leaks we offer three different techniques:
• EXTERIOR FLEXIBLE FABRIC REINFORCED WATERPROOF MEMBRANES
• INTERIOR POLYURETHANE INJECTION
• PRE-CONSTRUCTION INJECTION GROUT TUBES
Damproofing application to a new foundation (right-side)
and old foundation (left-side) cold joint.
Note lack of coverage on existing foundation wall.
Damproofing application. Note lack of waterproofing under the snap-ties.
These walls were inspected and approved for backfill.