Structures: Footings and Foundations

For this blog, I referenced my technical text books provided by Carson Dunlop. Also, most (if not all) of the illustration were provided by Carson Dunlop’s Horizon Reporting Tool.

082715_1925_StructuresF1.gifAs a home inspector, it’s important that I keep up with my education. It is also important that I review my text books from time to time, to make sure that I am following the Standards of Practice properly and that I am identifying all that I see.

Generally, home inspectors are guilty of conducting superficial structural inspections. The reason for this is that structural defects are less common than defects in other areas. When these defects do exist, they are more often than not, theses defects are very noticeable – unless someone has gone to great lengths to hide that fact.

I once heard a story of a home owner who went complete out of their way to hide a foundation problem. To the point where they had the old footing extended to support a new foundation, the weeping tile moved over. That new foundation the supported not the structure, but a façade exterior wall. The icing on the cake was that they had not extend the overhang of the roof. It would have been more cost effective to just fix the problem.

As a home inspector, my job is to evaluate the performance of the structure. Basically, it’s to answer the question: Is it doing its job? To answer that question, it’s best to ask: Has it withstood the test of time? That definitely makes answering the initial question easy. On new home builds however, I don’t have the ability to answer the validating question. So, in those instances I have to fall back to my knowledge of current building standards (not building code).

In some cases, many people believe that home inspectors do building code inspections – the reality is that these are two different vocations. Home inspectors are like the family doctor. If you have a knee problem, the family doctor refers you to a knee specialist. More often than not, a home inspector’s recommendations may actually be more stringent than the actual building code – depending on the knowledge and experience that the home inspector has.

How do I know if the structure has been standing the test of time and doing its job? If there are literally no signs of major movement (because all structures move, constantly).

Minor cracks in the parging – cosmetic; parging falling off the foundation wall – cosmetic; minor settlement cracks (minor as in a couple of millimeters). These are items to take note of and maintain. If there are any of the following, then it’s time to implement a solution:

  • Failure of interior finishes (large cracks where you can tell is actually shearing)
  • Undue stress on joints or individual components
  • The movement affects the home’s systems (windows/door not functioning properly; pipes that are broken; electrical wires that are taunt (This may not be structural at all, it may be an installation error), etc…)

The most important thing about structures is for it to satisfy the question: Can it safely support live loads?

What are live loads? Live loads are the people and things inside the home, the wind, the rain, the snow, or anything that pushes or pulls on the structure, or anything that stresses the structure that isn’t always there. Live loads can also be the water in the soil around the foundation; wet or frozen soil exert more pressure on the foundation then when it is dry.

The most important thing to remember about home inspectors is that we are not engineers.

Home inspectors should only report things that they have visually inspected – actually seen with their own eyes.

Let’s get into the meat of what footings and foundations are. What are the functions of structures? Their function is to stand still, but be flexible so they don’t break. That’s what they’re supposed to do, and more often than not, that’s what they do.

On a more technical note, footings and foundations do this:

  • Transfer live/dead load to the soil over a large enough area so that the building and the soil doesn’t move.
  • Prevent frost from moving the foundation/building.

Earlier I spoke about live loads, in addition to those live loads there are what is called dead loads: dead loads are weight of the building (foundation, exterior/interior walls, floors, roof, and everything that is built into the structure). It also includes the soil around the foundation.

Soils

Buildings rely on what’s under them, in most cases – its soil. Engineers (doing what engineers should do) design a building with the knowledge of the type of soil the building is going to be sitting on. Soil conditions are assumed to be a certain type, the footings/foundations are then designed for that location.

082715_1925_StructuresF2.jpgFoundations and Concrete Work (ISBN 978-1-56158-990-6)

Now, you need to understand that all houses settle. The amount maybe completely insignificant or even noticeable. Sometimes, it can be disastrous. The other thing that you need to remember is that because of variations in the soil properties, not every part of a foundation settles the same.

Failure to compact is what leads to cracking sidewalks and uneven driveways. – Foundations and Concrete Work (ISBN 978-1-56158-990-6)

Soil. Soil is variable, which means it can be made up of different types of soil that may actually differ from lot to lot.

082715_1925_StructuresF3.gif

You can build on all of these, except organic material. However, buildings must be engineered for that soil type, and again this type of information is beyond a Home Inspector. Home Inspectors are not soil engineers or geologists. Home inspectors provide home inspections that are intended to provide information regarding the condition of the systems and components of the building as it is inspected at the time of the home inspection.

The Standards of Practice are currently self-regulated. Currently [at time of this writing], in Canada, Licensed Home Inspectors only exist in British Columbia and AlbertaOntario has recently passed laws which will be implemented over-time.