Renovating an old home is like surgery: you are piercing through the protective outer layer and have to be mindful not to disturb the underlying systems and structures, unless careful thought and analysis has determined this is the correct option. Unfortunately, homeowners are often unaware of the structural and systemic impacts of their renovation and design choices. While contractors will often say everything is possible, some of the changes can negatively impact important structures and systems. The result can be extra costs and worry that make you question if it’s worth it.

To make more informed decisions, homeowners should learn about the changes they desire, including implications for the entire structure and the associated risks so they can make smart choices. Here are some insights from a structural engineer (a professional who specializes in advising how to make structural changes to a home) on two of the most frequently requested changes by Toronto homeowners – wall removal and basement lowering – as well as some additional comments about other unknowns that can present during any renovation project.

The Removal of Load Bearing Walls

These days open-concept floor plans are very popular. However, most old homes were not designed this way and use interior walls to help support the weight of the house. Consequently, when a homeowner wants to remove the wall between a kitchen and living room they are likely dealing with a load bearing wall. Removing or changing a major structural item like this can have far-reaching consequences and needs to be thoroughly considered. For example, the weight, previously distributed over the existing 12 foot wall, must now be redistributed to two columns, and these columns must transfer the load safely down to the foundation. This involves not only an assessment of the structural wall involved, but also the structural supports below. If the weight of the columns is too much for the beams or walls below, additional measures and expense will be needed. Further considerations (and expense) include the rerouting of any HVAC and piping located in this wall.

Basement Lowering (Digging Down)

With ceilings between 6 and 7 feet, the basements of older homes were previously built for the function of the home; to house things like coal shoots and milk boxes. But, today, as people look to add livable space to their homes, basement lowering has become a thing, and a conversion of these basements into a habitable space also includes other considerations like ventilation and waterproofing. Two ways to lower your basement are underpinning and benching.

Some insurers consider both types of basement lowering to be so risky that they charge professionals who do this type of work a higher premium. Underpinning requires professionals to undermine the structure of a house a small section at a time. While this is not true for benching, if it is done correctly, this procedure is also considered risky because it involves excavation.

To better understand how risky these procedures may be for your home you need expert advice about your foundation type and condition, footings, soil type and water table.  A geotechnical report would provide information about the soil type and water tables. We discovered a disintegrating foundation when we tore our house down – thank goodness we didn’t decide to renovate and lower our basement.

Other Unknowns

Beyond the complications that arise from structural elements of the home, one must also keep in mind that problems can lurk in hidden areas that are not structural in nature. Pre-renovation inspections are visual, perhaps with limited pilot holes. There may be indications of underlying issues of deterioration caused by things like rot and termites, or improper pre-existing structural framing. An example would be stairs that are not properly secured– which friends of mine discovered when they renovated their main floor, and the cost of their renovation grew. The point is, even the best structural engineers can’t foresee issues that won’t become visible until hidden spaces beneath walls and floors are opened up.  Homeowners need to prepare themselves for this reality when renovating an old home.

It Doesn’t Mean You Can’t Do It

If you are considering any of these options, you should learn as much as you can to properly weigh the costs and risks associated with making the desired changes with the value you will gain from the renovated space. This way you’ll be able to make a more informed decision and be better prepared for any issues that arise, like additional costs and extended timelines. If you were having major surgery, your doctor would encourage you and your family to learn everything about it to make it less scary and to allow you to prepare for any outcome or need for quick decision-making.

Wondering how to balance your needs and the risk when renovating an old home? We can help.

Special thanks to Jacob Kachuba of Tignum Design & Engineering Inc. for providing the structural engineering insights in this blog post.