Foundations

Foundation Solid State Inspections

If the two biggest natural enemies of our homes are gravity and water, the footings and foundation of our homes is the first line of defence. The footings and foundation of our home is expected to support the weight of our homes building materials, people, stuff, and even the weight of snow, rain, and winds. Our foundation also needs to keep our home dry by resisting water penetration from the soil and ground water.


Types of Foundations

Foundations are commonly classified as shallow or deep foundations. Shallow foundations incorporate a ‘footing’ typically resting on soil under the ground. The footing is the deepest point of the foundation and may only be 1-2 meters deep.


Deep foundations can use pilings which may drive down even several hundred feet to reach solid material to support the weight of the building. These are more commonly found on homes in soft soil areas or on large commercial buildings which need weight supported on bedrock rather than on soil.


Footings, Pads, and Walls

Footings are the lowest part of a shallow foundation system. The job of the footing is to transfer the weight of the structure to the earth and to resist movement from soil settlement, gravity, or frost heaving in cold climates.


In some foundation arrangements, a concrete ‘slab’ is poured and rests against or is built into the footings. The slab acts as a floor for the lowest level of the home but structurally may provide horizontal support to help the footings resist movement or it can be part of footings and carry some of the vertical loads. Slabs can also be independent of the structural foundation.


Foundation walls typically sit on top of the footings and carry the weight of the structure vertically to the footings as well as resist soil pushing inwards on a basement area. The combined system of the foundation footings, structural slab, and foundation walls all together make up the foundation.


Foundations Materials

Poured concrete is the most common material used today in home foundations. The advantage of poured concrete is it can be quickly poured to the homes dimensions on site and in any configuration needed by the home builder. Masonry blocks (either concrete or cinder) are less common today but were more common in the early 1900’s. Masonry block systems require more manpower and time to build. They can be used however when pouring concrete is not feasible.


Steel or concrete piles are other foundation materials typically used when solid soil is very far down or in commercial high rises where the building wants to anchor to bedrock. Wood piles and foundations have been used in the past but as wood is susceptible to rot, homes built with food foundations are not expected to have a long service life.


Cracks in Concrete Foundations

When concrete dries, it shrinks slightly and this can occasionally present itself as a hairline crack in the concrete. Small drying cracks in concrete therefore are often considered to be normal. Unfortunately, large cracks also start as small cracks so it is dangerous to diagnose a small crack as normal on only one observation.


Cracks (or cumulative crack groups) larger than 1/8” are typically defined as ‘large’ cracks. Large cracks often indicate some type of settlement or concentrated stress is on the foundation system and it may indicate an early failure of the system. Horizontal, vertical, and diagonal cracks can give clues to the type of stresses on the foundation system but careful observation and repeat visits are needed to diagnose if the condition is getting worse or has stabilized.


For home inspectors, cracks are very difficult to diagnose. While all foundation cracks present an opportunity for water to penetrate, most are not structurally significant. For a home inspector who is observing the foundation for a very brief period on one visit, it is even more difficult to determine if a crack is the start of a bigger problem or just normal. Most inspectors for this reason recommend further analysis of cracks.


Foundation Leaks

Water will always try to follow the path of least resistance and in some cases that will lead into our homes. Basements are like upside down swimming pools and water from the outside walls and soil will try to penetrate through the slab or walls into the home.  A good foundation drainage system will help direct water away from the walls and slab but cracks or holes in the foundation make an excellent path for water to enter.


When a foundation is determined to be leaky it can be a very expensive fix to repair it. Typically, the foundation needs to be exposed down to the footing, drain tile may need to be repaired and replaced, and a water proof membrane needs to be installed. This job requires specialized tools, equipment, and labour.


Foundation Failure

When a foundation has a structural problem, repairs are very complicated. If the footings are at fault, then digging low enough and replacing the footings in small segments is a very expensive solution. If the failure is in the walls or slab, reinforcing on the inside or outside may be the solution but can be very disruptive to the home. Repairing structural foundations is a major task which is why we want to foundation designed to last for the entire life of the home.


Final Thoughts

When buying a home, most buyers know it is important to get one with a good foundation. Hiring a good home inspector will help make sure you know your foundation is solid for your family for years to come.


By James Bell - Owner/Operator of Solid State Inspections Inc.