Last week, in the first part of our blog series on what you should know about your home foundation, we covered the basics of the two most popular choices for home foundations in Ottawa, concrete block and poured concrete. This week, we will look at two other types of foundations, Insulated Concrete Forms (ICF), and Slab on grade, that may not be as popular, but still offer some key advantages.
Insulated Concrete Forms (ICF)
ICF foundations are one of the most energy efficient options for home foundations. Comprised of polystyrene forms made of two expanded polystyrene (EPS) panels held together with connectors and reinforced with steel re-bar inside, they are assembled into place and then filled with poured concrete in order to create solid walls.
The forms interconnect to each other on each side and on top in a similar fashion to Lego blocks. The end result is a basement foundation that does not require insulation as the polystyrene forms filled with concrete provide a solid mass that prevents air leakage and air transfer and provides insulation itself.
ICF is also unique in that it can be used for the entirety of your home’s exterior walls, not just the foundation. This means that the panels can interconnect from the basement all the way to the roof line to provide a sturdy and insulated wall for the entire home.
Due to their strong insulating value, ICF foundations will save the homeowner on utility bills in the long run as they prevent temperature fluctuations from air leakage and also provide a comfortable basement living space in both winter and summer. They also provide superior noise reduction than other foundation systems.
From an environmental perspective, ICF foundations also provide a positive impact as the EPS is made mostly from recycled materials and can be considered a green building option.
In terms of disadvantages, ICF requires a knowledgeable builder for installation that may be hard to find due to the fact that it is not the most commonly requested foundation selection. ICF will also cost more up front for your exterior walls when compared to traditional wood framing or concrete foundation.
Also keep in mind that ICF, like all foundations, still requires proper waterproofing and a proper drainage system to keep water away from the home.
Slab on grade
Comprised of a single layer of thick concrete, slab on grade foundations rest directly on the ground and do not have basements. Despite being a less popular choice for foundations in Ottawa, the advantages to this type of installation are numerous.
First, eliminating a basement means no risk of water leakage through the foundation and no risk of flooding. Also, having no basement means your overall construction costs for materials and installation are lower.
The building structure also rests directly on the concrete slab instead of basement support beams and therefore provides a wide and sturdy foundation for the rest of the home. It also provides a faster installation than a traditional basement foundation would.
In terms of disadvantages, slab foundations have no access underneath the poured concrete slab for any wiring or utility lines. In addition, there is obviously no basement space to work with so your furnace and mechanical controls all need to find a home on the main floor.
Installation should also, as always, start with an analysis of the surrounding soil to determine how the footings will be installed to support the slab. As with all foundations, the surrounding soil is critical to analyze in order to determine how supportive it will be, how it handles moisture and how it might shift over time.
Insulation is also another key factor when considering a slab on grade foundation. In colder climates such as Ottawa, home foundations need to be installed to withstand the weather throughout the entire year. For slab on grade, it is usually wise to install horizontal insulation under the entire length of the slab to reduce heat loss in the winter months.