Do I need Piles for my Deck in Saskatoon?
When homeowners are planning to build a deck in Saskatoon, they are often confused what the proper foundation is for their project.
Sure, there is lots of information on Google and YouTube, but most of it is published by people around the world. Here is Saskatchewan, we have very different requirements then places like Texas or even Ontario. The long stretches of sub-40-degree weather cause our ground to freeze deep. Depending on the year, the frost depth can reach 8-10ft. These unique conditions require a special approach to dealing with the foundation. We are here to clear up the confusion and show the different options that are accepted and suitable for our climate.
Pad and Adjustable base ($)
The first option is to support the deck on a concrete slab with an adjustable base (see image).
For this method, the ground is tamped. Then a concrete paver is set on top. The pad carries the load from the deck and disperses it into the ground. The adjustable base is attached to the post and the assembly rests on the center of the pad.
This option is very popular due to its low cost. The entire set up is typically less than $40. For most applications this option is sufficient and works well. However, there are a few drawbacks.
As the ground freezes, water in the ground expands and forms ice lenses. This causes the ground to heave and shift. This in turn shifts the deck and moves it out of level. During the spring, when the ground thaws, the deck will often not return to the exact same position. An adjustable base (like the GH Leveller) can be used to move it back to the correct position but expect to have to go out with a wrench every 1-2yrs to re-level the deck.
The amount the deck shifts also greatly depends on the soil type. Soil types found in neighbourhoods like Brighton and Rosewood contain significant amounts of clay and fine soil particles. Unlike sandy soils, these types of soils trap water and further exacerbate the heaving effect.
Furthermore, if you have a new home, the soil around it is often backfill from the excavation. This soil often doesn't have the necessary compaction required to support a deck and can settle over time.
So what is the alternative if you want a long lasting, permanent foundation?
Screw Piles ($$)
The most common option for a permanent foundation in Saskatoon is a helical screw pile.
These are professionally installed with specialized equipment.
The machine twists the screw-like object 10-15ft into the ground. This ensures it has the required load bearing capacity and is below the frost line. More info on the science behind it can be found here.
The drawback to this option is the higher cost. This system typically costs $300/pile.
This decision between these foundation options is a lot easier if the deck is more then 6ft off the ground. In that case, the city of Saskatoon requires you to use a permanent foundation.
Screw piles are also highly recommended if you have any roof structure such as a patio cover or pergola. These structures can catch the wind and cause uplift. This has the potential to damage the deck or cause safety concerns. Screw piles – in addition to providing the necessary compressive strength will also resist any tension caused by uplift.
A professional deck builder knows all the code requirements to avoid costly mistakes and safety concerns. They can advise you on the best option for your specific project.
Contact MN Fence + Deck to start planning your deck project!
National Building Code of Canada