Choosing the proper foundation for new home construction

RENOVATING RIGHT by Gib Thompson

Published on January 23, 2017

Foundations are a significant part of your new home construction budget. Understanding the advantages and disadvantages to different building methods can help you select the best option for your budget and lifestyle. Whatever type of foundation you choose, you will want to make sure it is properly built to avoid costly repairs down the line.

Full BasementThe most common type of foundation is the traditional full basement with 8 to 10 foot walls poured on top of concrete footings. Due to the volume of concrete required, this is the most expensive type of foundation to build. 

With full basements, footings and slab are located 4 to 5 feet underground providing sufficient protection against freeze-thaw damage. Underground walls also allow for some natural climate control. A well-insulated basement will be cheaper to heat in the winter than a second story and will be cooler in the summer if you want to escape the heat.

Storage is another option to consider when deciding on a full basement. Some people know they will need extra storage room and may decide that having an unfinished basement is cheaper than building a garage. Basements also provide better accessibility to utility lines should you wish to remodel your home in the future and require modifications to utility routing or design. If you do go with a full basement, a cool option to consider is converting a portion of the space to cold storage – a great passive energy option for storage of root vegetables, preserves or home-made beer and wine.

If you consider finishing your basement be aware moisture issues are common if proper construction techniques are not followed. Waterproofing your foundation can be achieved through various products and properly installed drainage is key. Properly insulating your basement from the outside is best.  Ensure you wait an adequate amount of time for concrete to dry before installing finishes and consider the use of dehumidifiers for an extended period to ensure finishes do not absorb moisture as concrete continues to cure.

Slab on Grade – It is becoming increasingly popular to build homes without a basement. There are two types of construction techniques commonly used. The most common one is similar to a full basement where footings and a frost-wall are installed in two separate pours, followed by backfill and slab. Alternatively, true slab-on-grade construction refers to where both the footings and slab are poured at the same time. This type of construction can provide significant savings as less digging, formwork, labour and concrete will be required. Using less concrete also means reducing the ecological footprint of your home, the concrete industry is a large producer of carbon dioxide (CO2). Ground level homes are also a great option where accessibility is a priority and additional money can be saved on the construction and maintenance of stairs and decking.

Without a basement you need to consider where your utility room will be located. The type of heating system you decide to go with will impact size requirements. Utility rooms can be noisy so if they are located on the main floor you should install soundproofing.

In cold climates like Nova Scotia, the most common concern with slab-on-grade construction is the potential for frost heave and settlement leading to cracks in the foundation and/or structural movement resulting in damage to finishes. These types of problems can be expensive to repair. Proper insulation of slab on grade foundations is key to preventing frost penetration. In addition to insulation installed below and on the sides of slab, rigid foam insulation should be installed horizontally, below grade around the perimeter of the home to prevent frost penetration.

Poor construction techniques that can also lead to structural damage include failure to adequately control temperature and drying conditions during the pour. Pouring a foundation during winter months is not recommended, it can be done but will cost more as pre-heated concrete must be used and insulating blankets are required during cold snaps.

In the long run, the option to build with or without a basement boils down to budget and personal choice. In any case make sure your contractor is experienced and knows the technical requirements to establish proper grade, depth, compaction, and drainage. Proper site grading is also key to preventing water penetration over time. Ensuring foundations are properly engineered and professionally poured and finished will ensure a quality product to stand the test of time.  

Remember to look for my column in The News every Tuesday, I will be addressing a wide-range of home-related construction and maintenance topics. I welcome readers to submit questions by sending me an email at macgibcontracting@hotmail.com or call me at 902-695-5919.

Gib Thompson is a Red Seal Carpenter and owner of MacGibbons Contracting Ltd. In Stellarton, Nova Scotia.