Month: May 2020

You are getting ready to build your new deck, regardless if it’s wood, composite or a stone deck, creating a solid base is key! For those of us who live in Canada, winter and ground frost is a real concern. So, do deck supports shift with ground frost? The bottom line is if you choose the appropriate deck support for your job and you install them correctly, you will not have any issues.

Let’s quickly look at what ground frost is and do deck supports shift with ground frost. Without getting too much into the science behind ground frost, moisture is absorbed and held within the ground materials and as this moisture freezes it expands. When this material expands, it is displaced and can displace objects within, around or on its surface.

To determine what deck supports are right for your job, here are some main points to consider; what do local building codes require, if anything? What is the size and weight of your deck, as well as the elevation of it? What are the soil conditions that the deck is being built on? Besides the building code aspects, all these other factors mentioned will determine whether your deck supports shift with ground frost.

Please keep in mind these points are for purposes of discussion and any actual building plans should be validated by a qualified source.

When it comes to soil conditions, if you are dealing with a sandy soil you will already have an advantage. Sandy soil will hold less moisture and will be less affected by any freeze-thaw cycles. Sand compacts well, with little to no settling over time, if compacted properly. With this situation, it is possible to create floating deck footings. These are appropriately sized concrete blocks or pads, placed as frequently and where they are required, as per the design of the deck.

On the other end of the soil spectrum is clay soil. This is the most problematic soil and will cause deck supports to shift with ground frost when using floating footings. Clay will hold a lot of moisture and as a result of freeze-thaw cycles, will cause it to move and shift.

In-ground footings are by far the best and most reliable way to prevent your deck supports shifting with ground frost. These are either concrete footings or mechanical screw piles, both of which are installed below the frost line. The depth of the frost line will be determined by the area of your location, the average cold temperatures and how long they last.

When installing concrete footings, you need to determine the diameter of the footing required, and it is important to bell the bottom. The idea of this is to create a base that will act as an attached base pad, that is wider than the footing itself. This accomplishes two things: provides more support to the bottom of the concrete footing and, more importantly, prevents the deck supports from shifting with ground frost. Have you ever seen a fence installed and after one winter all the posts are pushed up and sideways? This is caused by the installer digging holes straight down and pouring cylindrical footings that are easily pushed up by ground frost. In some regions of Canada, you will find ground frost over 36” deep. When designing your concrete footings, it is important to determine the load requirements for each to ensure they are constructed appropriately.

This is why mechanical screw piles are the best choice to prevent deck supports shifting with ground frost. With mechanical screw piles, there is no guess work in ensuring you have the correct footings for your deck. Most reputable screw pile companies are able to recommend the appropriate size of pile, depth and torque it should be driven to, based on the size and weight of the deck and snow loads where it is being installed. Plus, the design and nature of a screw pile prevents it from being pushed up.

As you can see there are several choices when it comes to choosing the supports for you deck. If you select the appropriate one for your job, you will have no issues with your deck supports shifting due to ground frost.

You are planning on building a deck in your backyard, so what do you need to do? When preparing your site for a deck the first thing to consider is the materials you will be using to construct your new deck. Are you planning on building a wood or composite deck, or are you installing a stone deck? Is that stone deck being installed using traditional installation techniques or are you using some of the innovative products out on the market?

The first thing to take into account when preparing your site for a deck is whether your municipality or region require any permits. This really will be determined by the style of deck you are planning to build, such as whether you are physically securing it to the house and the overall elevation of it. In some cases, you may be required to have an independent engineer sign off on your project. It is always best to check with your local building department to find out what is needed.

The next thing to consider when preparing your site for a deck is access to the worksite. Will you need to take down any fences, hedges, or use a neighbour’s property for access? Are there mechanical structures or utility lines that have to be considered or worked around? This is particularly applicable if using traditional installation methods of stone decks and patios that involve excavation. Depending on your access, especially when limited, you may want to consider some unique products like; Gator Base, Silca SoilGrid, Paverdeck Plank, SilcaGrate and Paverdeck. All of these products are great to use when building those tight locations.

Now that you have determined the style of deck, sorted out all required permits, and figured out how to get the appropriate materials into your worksite, the next and perhaps the most important, part of preparing your site for a deck rests with what is required for the ground under and around your new deck. There are a few key components to this including; proper drainage of accumulating water from rain or snow melt, diverting any water that is coming off the house usually by eavestroughs, and adding a granular base for moisture control.

Assuming there are no issues with your current backyard and water is able to properly drain, you may find with the construction traffic around your new deck the ground can become very compacted. This could potentially alter the topography of the ground causing water to pool or flow towards your house, as opposed to away. All that to say, you want to ensure you have a good slope away from the house and the best time to address this is before the final deck is laid.

Now that you have the proper drainage in place, you want to ensure that any water coming off your house is carried away properly as well. Your home will either have water running straight off the roof or being caught by eavestroughs. Having water running off the roof and continuously hit your deck in the same spot every time it rains, or snow melts will result in your deck being discolored or even damaged in that area. When water is directed by eavestroughs, they usually push the flow of water 3 feet away from the foundation. This typically will fall under your new deck or on top of your new patio. Having water flow across your new stone patio will cause the polymeric sand to wash away over time, as well as discolour the stones in that area. Having water continuously flow under the base of the deck in the same spot will eventually wash away the slopes you created and can cause damage to any footings nearby.

Adding a gravel base under the deck may not seem so important when preparing your site for a deck, but it helps the area under the deck to dry out quicker, helps with water flow and makes for an uncomfortable bedding area for any critters that may want to call your new deck home.

Preparing your site for a deck can require additional considerations, depending on the design and any other mitigating factors. The ones covered here are the basics that can be applied and should be considered for most deck builds. Welcome to the Deck Revolution.