Everything You Should Know About Slab On Grade

Have you ever been in a house that didn’t have a basement? If you’ve lived your entire life in Canada or America, chances are you haven’t. This is because we come from a long tradition of homes with basements, stretching back to times before refrigeration and heating when basements were used to store food. As technology progressed, we turned to our fridges and grocery stores for our food storage, we re-purposed our basements into rec-rooms, workshops, general storage, and trendy man caves! Our evolved history of family having basements as a standard home feature mingled basements into our culture to such an extent that we rarely ever question their necessity.

Do You Actually Need A Basement?

The inclusion of basements into almost every new home built in Canada is a bit of a harmful trend, from the environment to homeowners pocketbooks. From the quarry to your home, every tonne of cement required to construct a basement foundation creates approximately one tonne of carbon emissions, and the average basement foundation requires 75-100 tonnes of cement. This is a tremendous environmental cost, but also a financial one. After foundation, subfloor and flooring are completed, a homeowner will be lucky to spend under $40,000 for an unfinished basement. We generally don’t think twice about this investment, because basements are something people generally believe homes just have. The investment isn’t considered an option, but fundamental to what makes a house. But that’s false!

Basements are investments that can provide value, but when built simply for the sake of building, generally don’t. If you don’t have a designated purpose for your basement in the design of your home, you are raising the cost of your build by 10% or more for absolutely no reason. Basements that do not have a designated purpose generally remain unfinished and neglected areas of the home, where neglected things go to accumulate dust. Though they are not used, they still require money to heat and cool, they produce musty air, and basements require costly maintenance as foundation cracks form over freeze-thaw cycles.

Consider the possibility of avoiding these costs by building a home with a slab-on-grade foundation. This building method avoids all the environmental and financial pitfalls of a basement foundation, and brings a range of advantages that basement foundations simply cannot offer.

What Exactly Is Slab On Grade?

Slab on Grade is a very simple idea. Instead of digging down and emptying an average of 3 cement trucks to pour a basement foundation footing, floor, and walls; A slab foundation only requires you to level the ground your home will be sitting on and pour the floor of your house. This reduces the carbon cost of your home to 1/3^rd of a basement foundation, but also saves you a tremendous amount of money compared to a full basement, both with respect to initial investment and the savings on not having to heat/cool your basement.

Environmental Efficiency

The environmental benefits of slab-on-grade foundations can’t be understated. A popular choice for LEED, BOMA, and Passivhaus building projects, the benefits of slab foundations go beyond just upfront carbon savings. Slab foundations have considerably more thermal mass than basement foundations, storing and releasing heat during the winter; and rejecting it in the summer. Slab foundations are a popular starting-point for passive homes for this reason. While you may not be building to such a high standard, you can still take advantage of the efficiency bonuses of slab-on-grade. In addition to the fact that you don’t have to heat/cool a basement, the passive solar benefits of a slab foundation will substantially reduce the energy requirements to heat and cool your home for as long as your building stands. Should you elect for slab-on-grade, speak with your architect about maximizing its ability to passively heat and cool your home.

Save Money In The Long Run

There is a common argument that a slab foundation will produce a home of lesser value than an equivalent house with a basement. While in North American markets, this is generally true, it does not logically follow that slab-on-grade is a poor home investment. Comparing only the sale values of two equivalent buildings, one with a basement foundation and another with slab, the building with a basement foundation will sell for more. That said, it will also cost more to build, and cost more to live in. If you factor in the savings during the build stage, and the on-going passive savings on heating and cooling, if and when you sell, you are likely to find yourself on an equal (if not better) net financial position than someone selling an equivalent home with basement foundation.

Details To Consider

To get the most out of the benefits of a slab foundation for your home build, you’ll really want to give special emphasis to your home design. Furnaces, washing machines, water heaters; everything that you would typically relegate to the basement will need to be provided a space aboveground in a slab-foundation home. Moreover, you’ll want to give thought long-term with respect to your needs for space. The carbon and cash savings of a slab foundation are essentially negated if you plan on pouring more concrete and building an addition in a few years, when you could have simply elected for a basement initially and renovated it to suit your needs when they presented themselves.

Like any building method or material, slab on grade foundations have their pro’s and con’s, and are not suited for every circumstance and context. For instance, if the plot you plan to build on is on a slope, then there is simply no sense in a slab foundation. Building on a slope require extensive digging to establish a level footprint, and concrete walls to resist shifting soil. In this case, it would be in the better interests of a homeowner to build a walk-out basement, as the circumstances of the build more or less require them to build one.

To add space, slab on grade requires you to build either up or out, so it is essential that you consider municipal restrictions for footprint and height when considering what kind of foundation you ought to choose. If these restrictions limit your ability to build up and out, you may be required to build down to accommodate your needs for space, and such a slab foundation may not be for you.

Is Slab On Grade Right For You?

Basements are useful, but not necessary. A long tradition of basement living can make us uncomfortable with the prospect of forgoing a basement foundation, but we ought to recognize that the benefits of basement foundations come at extraordinary costs that can be avoided with a slab-on-grade foundation. Considering slab-on-grade instead of traditional basement foundations confers tremendous environmental benefits, lower upfront-costs, and a passive reduction on utility costs for heating and cooling. Like any building method, slab-on-grade has its pro’s and con’s that make it a better or worse choice depending on the unique circumstances of a build.

With the right design, the detractors of slab foundations can be reduced or done-away-with entirely, and the benefits can be maximized, making slab-on-grade a fantastic choice for home building in Ottawa. Get in touch with us to find out more about how Windmill Construction and the benefits of slab on grade.