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Your Guide to Deck Foundations in Winnipeg

What are your foundation options for building a deck in Winnipeg, and how to you choose the right one? Find out in this comprehensive guide as we dive into common solutions and what need to know about them.



Deck foundations. Wait, don't click away from the page yet! We know the foundation might seem like a relatively boring part of building a deck, but it's actually the most critical aspect of the whole project.
After all, imagine having to deal with a deck that's sagged, tilted, or sunk because of a bad foundation. You only built it a couple seasons ago and are already shelling out big bucks for repairs. Not a good scenario, but it's the unfortunate reality for countless homeowners in Winnipeg.
That's why we're breaking down your options for deck foundations and digging-up the key information you need to know about their performance in Manitoba soils. Surprisingly, it's not quite as straightforward as you may think.
We'll be exploring common solutions like poured concrete, deck blocks, manual ground anchors, and helical piles. Each one brings something unique to the table, along with its own "perks and quirks".
Today, we'll walk through how each of these works and unpack the insights you need to confidently choose the right foundation for your deck. Because let's face it... when it comes to enjoying those fleeting summer moments outdoors, your deck needs to be just as reliable as it is beautiful.

The Importance of a Solid Foundation in Challenging Winnipeg Soils

Ever wondered how a towering tree stands tall for decades, enduring harsh Manitoba winters and vicious summer storms? It's all about strong roots. Firm support below ground ensures they'll continue standing above ground.


If you want your deck to endure those same forces of nature, it also needs strong roots in the form of a solid foundation.
Don't make the mistake of under-estimating the immense power of natural forces like freezing, thawing, moisture, and soil movement. They have the ability to change entire landscapes over time and can absolutely cause damage to your deck.

But, what is it exactly about Winnipeg that is so darn hard on deck foundations?

Why Winnipeg Weather (and Soil) is So Hard on Deck Foundations

We're not sure where the nickname "Winterpeg" came from, but it's probably the most accurate way to describe our fair city in a (chilly) nutshell. In fact, most of us are strangely proud of how frosty it gets during the winters!

Unfortunately, our tough winters can cause a host of problems for your deck foundation. More specifically, it's the combination of brutally cold winters and a unique soil composition known as "Manitoba gumbo".


Most of the soil in Winnipeg is clay or silt, with some areas also featuring higher amounts of sand as well. It's known as "expansive soil", meaning it will expand and contract alongside moisture levels.
When the dirt gets saturated by rain or snowmelt, the clay particles expand to hold that moisture. As it dries out, those clay particles release their water and shrink in size.

Now what happens when expansive soils meet harsh winters, heavy rains, and dry seasons? They experience constant movement and shifting. If you've ever noticed cracking in your concrete or patio pavers out-of-place after spring melt or dry periods, that's our soil at work.

The one-two punch of expansive soils and a wildly varying climate puts enormous pressure and stress on any foundation. It's also the biggest reason you'll find Winnipeggers building their decks on deep foundations to overcome our difficult conditions.

So what are your different options for building a durable deck, and how do they compare to each other? Time to take a look!

Concrete Foundations for Decks: A Traditional Choice

The Romans were one of the first, and most extensive, users of concrete in the history of the world. With it they built some of the most famous buildings and monuments ever seen, and many still stand today. More than 2,000 years later, some Roman concrete is just as strong as the day it was poured.


These days our concrete is significantly different than Roman formulations, but the idea remains the same. You mix aggregates, water, and cement, which causes a chemical reaction in the concrete. This reaction, eventually, transforms the fluid concrete into a solid. Modern concrete is also unique in that it uses re-bar reinforcement to increase its strength, performance, and durability.

Concrete foundations for decks aren't quite as old as Rome, but they have been a common option for many decades. Odds are you've either stood on, or have owned, a deck built on a concrete foundation at some point. Winnipeg in particular found a fondness for concrete deck foundations over the years, as it can provide a more stable footing than something like surface deck blocks.

There's some undeniable benefits to concrete foundations, such as the ability to install them yourself. On the other hand it can be a disruptive process. Let's walk through what it takes to get a poured concrete deck foundation, its perks, and some important considerations.

Installing a Poured Concrete Foundation - Step by Step

1: Design the Layout


First, you need to decide how big to make your concrete footings and where to place them. This is done by assessing the weight and structural loads of your deck. It's vital to get this right the first time, as once the hole is dug and concrete poured you'll be committed!

2: Excavation


In order to pour concrete into the ground, you'll need to make room. The quickest and easiest way to do this is to use a soil augur attached to an excavator or skidsteer. You can also rent hand-operated augurs or even dig by hand, but that's a big (and sweaty) task. In any case, the holes must extend below our 6 foot frost line.

3: Place Concrete Forms


Concrete can't be poured directly into the hole, it needs a form to hold the shape while curing. This involves setting a cardboard tube into your excavated hole and ensuring it reaches the bottom.

4: Set Rebar Reinforcements


Before pouring, rebar reinforcements must be installed in the form and secured in place to prevent movement.

5: Pouring the Concrete


With the rebar in place, concrete can be poured into the form. Care should be taken while pouring to prevent voids (areas with no concrete) and guarantee proper settlement of the material. Watch out for movement of the rebar as well, you want it to remain centered in the form. This is also when you'll insert an adapter into the wet concrete to make the transition to your deck posts.

6: Curing Time


After the pour is done, there's nothing to do but wait. How long you concrete will take to fully cure depends on several factors such as temperature and weather conditions. Plan for at least 2 weeks before the concrete is safe to build on, but it could be longer during rains or cold snaps.

Upsides of Concrete Deck Foundations

    Can be done as a DIY project, making it a relatively affordable foundation option
    If installed properly, concrete can provide good performance for many years
    More durable than buried wood posts or surface deck blocks

Downsides of Concrete Deck Foundations

    Slow, time consuming, demands a lot of work to install
    Causes significant disruption to the land, can leave a mess behind
    Can be more prone to the affects of frost-heave
    Future removal would demand extensive excavation and replacement of soil

Deck Blocks: Quick & Easy (With Caveats)

You've probably seen these piled on palettes outside of home improvement stores and garden centers. Deck blocks are a very popular option to support decks in Winnipeg, likely because they're cheap to buy and easy to install.
The design of a deck block couldn't be more straight-forward. It is, quite literally, a chunk of concrete with an area on top to set a deck post or beams. And that's pretty much it!


Photo courtesy Todd Turner on Flickr, CC BY-NC 2.0 Deed license

We can't argue with the convenience of a solution like this, as you could lay an entire deck foundation for a hundred backs and an afternoon of work. Unfortunately, convenience doesn't always mean the best results.
A big concern we have with a solution like deck blocks is the fact they simply sit on the surface of the ground. Only the weight of your deck keeps them in-place. That means there's nothing to prevent them from moving all over the place during our freeze/thaw cycle.
Not to mention the City of Winnipeg won't approve deck blocks for decks over 592 sq. ft. in size or over 4'-3" high.
But, before we get too negative, we'll assess how to use this "cheap and easy" deck foundation and what you should watch out for.

How to Use Deck Blocks

1: Design


Choose how many deck blocks you'll need, and where to place them, based on the design and structural loads of your deck. Remember that deck blocks only sit on the surface, so if too much weight is applied they will sink.

2: Site Preparation


Level the areas where your deck blocks will sit so they have the best platform possible. Adding gravel under each block can provide some protection against movement during freeze/thaw and is recommended by the City of Winnipeg. That would require digging an area under each block and adding material.

3: Place Deck Blocks


Image courtesy of Matt Haughy on Flickr, CC BY-NC-SA 2.0 Deed license

Drop a block at each of your predetermined spots, and make sure it's set as firmly as possible. Performing some compaction before placing the blocks can improve the overall quality of installation.

4: Inset Posts or Beams


Photo courtesy Todd Turner on Flickr, CC BY-NC 2.0 Deed license

At this point, the deck posts or beams can be set into the designated areas on the blocks and you can proceed with your build.

Benefits of Deck Blocks

    Cheap to buy and relatively easy to place
    Not permanent, can be re-located
    Does not require excavation to install

Problems With Deck Blocks

    Not approved in Winnipeg for decks over 592 sq. ft. in size or more than 4'-3" high
    Cannot be used for decks attached to a house in Winnipeg (unless special approval is granted)
    Highly prone to sinking, shifting, and movement
    Relatively low weight limitations (unsuitable for large decks)
    Performance cannot be calculated or guaranteed

Manual Ground Anchors for Decks: Buyer Beware

We promise to not be too hard on this foundation option for decks, but there truly are some important things you should know about it. Especially because manual ground anchors are often mistaken for helical piles, when in fact they couldn't be more different!
To start though, let's talk about what a manual ground anchor is. Like deck blocks, you've likely seen these at a local Home Depot or Rona. At first glance, they look like a perfect way to get the strength of concrete with the DIY-convenience of deck blocks.


Ground anchors typically come in a couple of different designs.
The first are steel tubes around 4 feet long. They weld a spiral plate to the bottom and attach a U-channel plate on top. You place a 2x4 into the U-channel and turn the anchor down into the ground with good old-fashioned elbow grease. Some brands sell extensions so you can turn the anchor deeper than 4 feet.
Another common style of ground anchor quite literally looks like a giant screw. You install it the same way - by turning it into the ground with a length of 2x4. There are no extensions available for this type of anchor.
While we're big fans of the DIY spirit and saving money, the performance of manual ground anchors leaves much to be desired. Because you have no way to confirm their performance, you're only guessing that you've installed them deep enough. In Winnipeg, that means going down to at least 6 feet and possibly beyond.
Installing a ground anchor to that depth is extremely difficult and impractical. Some people have reported they destroyed the anchor trying to install it a mere 4 feet deep!
While we said we'd try to not be too hard on this foundation, we've seen too many people waste time and effort installing them. Still, let's take a closer look at how they work...

A Closer Look at Using Manual Ground Anchors

1: Design


There's no escaping it, you have to start by determining the number of anchors you'll need and where they'll go. Be careful to accurately mark your anchor locations, the last thing you want to do is try and remove one after muscling it into the ground.

2: Install Ground Anchors


Screencapture from YouTube video

With a bit of elbow grease (okay a lot), you'll turn the ground anchors down into the soil. If you have particularly dense or clay-heavy soil, it may even take another person to help do the job.

3: Build Deck


Place your deck posts or beams on the ground anchors according to your design and the manufacturers directions.

Why Choose Ground Anchors?

    Low-cost solution compared to other options
    Can (in theory) be installed by hand, DIY-style
    May be suitable for extremely lightweight detached decks

Why to Avoid Ground Anchors?

    No way to prove performance or quality with hand-installation
    Challenging to install an accurate and quality foundation by hand
    Very difficult to secure beneath the 6' frost line (will not be approved by Winnipeg for decks over 4'-3" high)
    Force of installation can actually damage the ground anchors
    Most ground anchors can only accept a maximum 4x4 post

Helical Piles for Decks: A Foundation for the Future?

Imagine if you could get the strength of a concrete foundation for your deck, without excavation or disturbance to your yard.

You might want to consider helical pile foundations!

First invented in the 1830's this unique foundation solution was originally intended for use under lighthouses, bridges, and piers. Over the past 180+ years they've seen extensive use in residential and commercial projects.


Unlike other foundations that require excavation or ground disturbance to install, helical piles smoothly advance into the ground using hydraulic power. The "helix plates" provide plenty of surface area needed to firmly anchor in the soil and prevent movement.
Now, we can't lie, we're obviously biased towards helical pile foundations for deck projects. But there's good reasons for it!
Because of the way we install a helical foundation, there's no holes to be augured or concrete to cure. And even though it may not look like it at first, helical piles are capable of supporting immense weight in typical Winnipeg soils.
Better than that, the combination of wide helix plates and narrow shaft means that a helical pile defends against movement from frost much more effectively than other solutions. That's crucial when supporting a relatively light structure like a deck.
Finally, if you ever find yourself needing to remove the deck, your helical foundation can be reversed out of the ground and potentially even re-used upon inspection.
They might not be the cheapest foundation option out there, but it's hard to beat the raw performance and longevity of a helical pile foundation!

How a Helical Pile Foundation for Decks is Installed

Here's the rub with a helical deck foundation - you can't install it yourself. It takes specific training, equipment, and knowledge to do the job properly the first time. The good news is that having a helical foundation installed is a painless and easy process when you work with a quality contractor.

1: Determine Foundation Design


There's several factors that go into identifying which helical piles are suitable for your deck. We don't want to give you more, or less, support than you need so this step is key. How many helical piles you'll need depends on factors like the size and style of your deck, soil conditions, and structural loads. A great contractor will take the time to carefully assess your designs and deliver an engineered solution.

2: Mark Pile Locations


Before your piles can be "screwed" into the ground, we have to know where they should go! This is determined based on your deck plans and can be done either by yourself or with your contractor's help.

3: Install Helical Piles


One by one, each helical pile is turned down into the ground using a special "anchor drive" attached to equipment like mini-excavators or skidsteers. Our team uses professional ground mats to protect landscaping, ensuring the machines leave no mess behind. Not all contractors are as careful about your property, so make sure you always ask how they plan to protect your lawn.

4: Attach 'Pile Adapters'


To make the transition from your foundation to the deck a simple one, U-bracket or L-bracket adapters are attached to the tops of your helical piles. This allows you to attach your deck posts quickly and securely. These adapters are even adjustable to ensure a level result.

5: Build Your Deck!


That's it, you're ready to build your deck on a sturdy support! Simply set your posts or beams on the foundation and you're ready to go.

Benefits of Helical Piles for Decks

    Fast installation with no disturbance to your property
    Offers the strength of concrete in a more efficient package
    Approved by City of Winnipeg as a deck foundation
    Will not shift or move during our harsh winters
    Installation can be monitored in real-time for quality
    Does not require tearing-up a part of your yard

Considerations of Helical Piles for Decks

    Not a DIY solution
    May cost more than other options
    Incorrect installation will lead to problems
    Not suitable for extremely rocky soils, or areas with bedrock at the surface

Which Deck Foundation is Right for You?

Alright, we've covered a lot of information so far and you might be feeling a little overwhelmed at all your options for deck foundations in Winnipeg. Don't worry, we have your back!
Let's break down each of the foundation solutions we covered today and see how they stack-up in four categories:
● Foundation Cost● Installation● Durability● Suitable for Winnipeg

Foundation Cost

  • Concrete Foundations

    Professional versus DIY installation will have a big impact on the expense of a concrete deck foundation, but typically the costs will be towards the higher end. There's a fair amount of preparation work required in terms of digging, setting forms, laying rebar, and so on.

  • Deck Blocks

    Of all the foundations for decks, these will likely be the most affordable. Deck blocks are usually less than $20, and the cost of some gravel to go underneath them. The trade-off is that deck blocks are among the least stable solutions and aren't approved for use under larger or higher decks.

  • Manual Ground Anchors

    Another relatively low-buck foundation choice, manual ground anchors can be cheap to buy and install. But, the price of this cheapness is unpredictable and inferior performance compared to more sturdy alternatives.

  • Helical Piles

    Generally speaking, a helical foundation can be the pricier option compared to everything we've looked at. However what you get for the slightly higher cost is a faster, cleaner, more effective support for your deck.


  • Concrete Foundations

    Can be slow and labor-intensive to install, with curing alone taking up to two weeks or more. Creates piles of excavated dirt and other material to clean up.

  • Deck Blocks

    Beyond digging a small area where the block will sit and laying gravel down, there's not much to the "installation" of a deck block.

  • Manual Ground Anchors

    In theory, these should be easy to install. Reality looks a little different, as we've seen stories from homeowners who were unable to turn the anchors into their ground by hand.

  • Helical Piles

    Mini-excavators or other compact equipment is used to quietly turn each pile into the ground at a constant rate. Quick, easy, clean.

Durability and Longevity

  • Concrete Foundations

    Often has a good lifespan if properly poured, but harsh winters or poor installation can affect long-term performance. May be susceptible to frost-heave under light structures such as decks.

  • Deck Blocks

    Very poor durability as they are extremely prone to moving along with the ground. Could shift significantly out of place in a single winter season.

  • Manual Ground Anchors

    It's difficult to say what the true durability of a manual ground anchor could be, but there has been reports of homeowners destroying the piles simply while trying to install them which doesn't spark immense confidence.

  • Helical Piles

    Our helical piles are rated for a minimum lifespan of 50 years, and will likely last much longer. Resistant to corrosion, frost heave, and high water tables.

Suitability for Winnipeg

  • Concrete Foundations

    Whether concrete is suitable for deck foundations in Winnipeg is a bit of a "yes and no" question. Yes concrete can be a reasonable foundation for certain projects, but it may not be the best for lightly-loaded residential structures such as decks.

  • Deck Blocks

    No, no, and no. They're only approved for use under small, short decks and offer very little in the way of true structural stability. The odds of them shifting around during our freeze and thaw cycle is extremely high.

  • Manual Ground Anchors

    These might be an acceptable choice for things like mailboxes or other very small projects, but we're not confident they can hold-up a deck over the long term in Winnipeg. Some homeowners have found success with them, but those appear to be few and far between.

  • Helical Piles

    High performance in Winnipeg's challenging soils, resistance to frost-heave, and great convenience, have made helical piles a popular foundation for decks in our region. A good pick for long-term support.


Wow, that was quite the journey into your options for a solid deck foundation. Bet you didn't know there was so much that goes into it!
The reality is that foundation science, even for a deck, is pretty complicated stuff. That's why it's crucial to take the time and consider which solution is best for your unique situation.

After all, building a deck is a whole more more than slapping a few planks of wood down in your backyard. You're creating a welcoming place for family gatherings, weekend get-togethers, and quiet sunsets - an outdoor extension of your home.


Yet those happy memories won't be quite so bright if your sinks, sags, or slips away from your house because of a failing foundation.

Which one you should choose truly does depend on your specific situation. While we'd love to tell you to pick helical piles and call it done, that's not the case. Some projects could hugely benefit from a helical foundation, and some projects can't even use them at all.

So, the best way to hone-in on what's best for your deck project is to...

...get in touch with an experienced and trustworthy helical foundation contractor!

They can help you determine if this streamlined support is suited to your situation, or be honest if you should look in another direction.

Psst, you can always reach out to our friendly foundation team to discuss your options for holding-up a deck in Winnipeg! Drop us a line below.