The Top 5 Mistakes Made When Preparing Footers For A Deck

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The footers are the concrete supports that sit under the deck's posts and keep it from sinking into the ground. Without strong and sturdy footers, the deck is a safety hazard and won't pass a local building code inspection. Get your deck building started on the right foot by avoiding these five common mistakes.

Forgetting About Frost Heave

No matter what part of the country you call home, the freezing temperatures of winter put the integrity of your new deck at risk. Before you start up your rented concrete mixer and start pouring the footers, make sure your holes go down below the frost line. This line marks the depth at which soil resists freezing, which prevents the concrete from cracking or being pushed upwards as water below it freezes.

The frost line varies from area to area depending on the average low temperatures in the winter. Check the charts provided by the Ontario Ministry of Environment to figure out how deep it lies on your property based on your location and soil type. Plan to dig your footer holes at least six inches below the line for year round stability.

Sitting Piers on Loose Soil

New home sites are graded to create a nice flat spot for a foundation. The grading work leaves a lot of loose soil piled around the home, also known as back fill. Sitting your poured footers or pre-cast piers on top of this dirt puts the entire deck at risk for collapse.

You'll need to dig down and reach undisturbed soil for safety. It can take a hole reaching eight feet deep or more to hit this type of ground, so consider renting an auger or other excavation tool along with your concrete equipment rentals. It'll save you a lot of back-breaking labor, especially when digging down in rocky soil.

Skimping on Footing Size

Too many homeowners try to save on concrete material costs by pouring a footer that is exactly the dimensions of the posts above or even smaller. Undersized footers cause problems like:

  • Shaking and swaying when the deck is in use
  • Sagging joists that create dips and bows on the surface of the structure
  • Warped supports that eventually twist or crack
  • Collapse when the support posts slide off the footer entirely or break

Hitting Buried Lines and Pipes

It's fine to do your own digging and pouring to start off your new deck project. However, don't forget to take basic precautions and call your local utility companies before setting your shovel in the soil. Hitting a buried power line or high pressure gas line as you excavate for concrete footers will leave you seriously injured or dead.

Cracking a water main, cable line, or other buried connection is a little less dangerous for you personally, but it will still damage your property and cost you a lot of money to fix. If you live in an older home where forgotten cables and pipes are likely, consider a quick underground scan from a locating company to make your home improvement projects a lot safer.

Missing the Moisture Barrier

Concrete wicks moisture out of the ground and can spread it into the wooden posts of your new deck. When rot sets in, you might as well have skipped the hard work of setting up the footers in the first place. Install the metal moisture barrier brackets designed for this problem on top of the concrete as it sets to protect your deck's support posts.

With some planning and the right rented concrete equipment, you can quickly create deck footers that last for decades. Putting the extra time and effort into this part of the installation process pays off in the long run. Build a deck you can trust by starting with a concrete base that won't shift, crack, or sink.


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