Is a Floating Deck a Good or a Bad Idea?

Adding a deck to the backyard giving a level platform to set up a few chairs to enjoy the sun and maybe grill some burgers seems like a good idea. But what type of deck? Should you dig frost footings, or is a floating deck a good idea? When is it better to build a floating deck? What are the pros of a floating deck? What are the cons of a floating deck?

A floating deck is a good idea for a low ground level deck, less than 24″ (600mm) above grade. A floating deck is beneficial for around a tree as not to disturb the tree’s roots. Building a floating deck is a good idea, with it’s reduced costs compared to a fixed deck.

A floating deck is not all good. There are some cons to a floating deck. But let’s cover why and when a floating deck is a good idea but then also the cons. Reason why a floating deck may not be a good idea.

Reasons a Floating Deck is a Good Idea

The primary reason a floating deck is a good idea is during construction. The most significant difference between a floating deck and a fixed deck is the footings.

A floating deck does not have footings below the frost level but floats on deck blocks installed at grade. Where a fixed deck requires footings installed below the frost level. Where in places like Texas, the frost level is between zero and 12″ (300mm). But jumping countries and city to Winnipeg, Manitoba, where the frost level is 72″ (1.8m).

Regardless of where you are located, a floating deck will require less digging and cost less.

Floating Deck A Good Idea Costing Less

First, you will save money with a floating deck. There are three ways you will save money.

  1. Comparing Floating Footing Material Costs to Frost Footings. How much varies by the footing requirements but using Calgary as an example. In Calgary, requiring footings 10″ (250mm) diameter footings, 4′ (1.2m) deep will cost $60 in material. For the concrete, forms and post saddle. A floating deck block will only cost $15 for the deck block and base materialOpens in a new tab. like gravel under the deck block. Saving you $45 per footing. With a floating deck saving you a minimum of $200 compared to a fixed deck in material.
  2. Floating Decks Take Less Time to Build. How deep and how hard the ground is will impact how much time savings. But on average, in Calgary, where I build decks, you will save around two hours per footing. With a small deck, only requiring four footings, that is the difference between framing in the afternoon or spending all day digging holes and mixing concrete. The larger the deck, the more time you will save with a floating deck instead of a fixed deck.
  3. Less Dirt to Dispose of With a Floating Deck. Yes, you can rake it out under the deck. Or like my neighbour did pile it up around his house’s foundation. But you need to do something with all the extra dirt from the footing holes.

The challenge with dirt from footings holes is it is mostly clay. Which is not good for your yard and grass. As nothing will grow in it. Even if you use it to fill holes or low spots in the yard, you will need to buy loam to cover the clay for the grass to grow in.

If you decide that wrecking your yard is not a good idea, you have to haul the dirt away. This can be as simple as loading up a few buckets and driving to the landfill. But often, this includes dumping fees or waste bins to haul away the dirt. All added up to paying a few hundred dollars more for fixed deck footings than a floating deck.

These three reasons alone make a floating deck a good idea. But there are more.

Floating Deck a Good Idea for Certain Locations.

As I mention in cost, the first is where the frost level is so deep that extensive excavation is required for frost footings. Making a floating deck a great idea. But also were in the yard the deck is located.

It may be a good idea for a yard with many trees to build a floating deck instead of a fixed deck. With the many challenges involved with building a deck over tree rootsOpens in a new tab.. Not only is it time-consuming digging among tree roots. As they slow down digging, often requiring reaching into the hole with a saw to cut roots. But it also can be bad for the tree. Larger roots close to the tree trunk are critical for tree strength and water.  Cutting these roots on a tree while building a deck can kill the varied tree you are trying to design your deck around.

A floating deck disturbs tree roots less. As the deck blocks can be installed above grade, away from significant roots. Making a floating deck a good idea around or close to a tree in your yard.

Floating Deck’s Don’t Require Permits?

Before discussing when a floating deck is not a good idea, I just want to clear up a common misconception, permits.

It is often mentioned that a floating deck does not require a building permit. This is not true but is a problem of causation and collation.

As required by International Building Code, a floating deck must be less than 30″ (762mm) from the ground. Slightly lower in Canada at 24″ (600mm) above grade.

Checking many cities deck permitting requirements, it’s the height of the deck that requires permitting, not the footings.

“You need a construction permit to build a deck that is more than 18 inches above the ground”

Government of SeattleOpens in a new tab.

Using Seattle as an example, but this is common in many cities. In fact, I didn’t find any cities that differ between footings type for the requirement of permits. When pulling a deck permit, they will often have footing requirements. It’s not the footing that demands permit but the permit that demands footings.

In short, whether or not a floating deck is a good idea, the permit requirements have little impact. Floating decks don’t require permits because they are low to the ground, not because they are floating. 

Reasons a Floating Deck is a Bad Idea

There are times and reasons when building a floating deck is a bad idea.

Primarily, just as we discussed with permits.

A High Floating Deck is a Bad Idea

Any deck above 30″ (762mm) in the States and 24″ (600mm) in Canada need frost fixed footings. A deck of that height requires the stability of footings installed below the frost level. A floating deck movingOpens in a new tab. with the ground can have serious consequences. Causing the deck to collapse with the potential of injury from the height of the fall.

A ground-level floating deck may sink in spring, but the potential for injury is low. Falling two feet is a lot less dangerous than falling six. Making a tall floating deck a bad idea.

A Floating Deck Connect to the House Is a Bad Idea

A low freestandingOpens in a new tab. deck beside a house can have many advantages. But the deck cannot be attached to the house if floating.

A floating deck will cause stress and possibly failure of the house’s foundation. As the deck moves with the ground, the deck will pull or push the foundation. The house’s foundation is not designed for this level of lateral load, increasing failure potential. Making a floating deck connected to a house a bad idea.

Conclusion, Is a Floating Deck a Good Idea?

Yes, a floating deck is a good idea if the deck is low, not attached to the house or built close to trees. A floating deck will save you both time and money during construction.

But a floating deck is a bad idea if the deck is tall or is attached to the house. The movement of a floating deck do not work well when connected or at heights. These situations require a fixed deck supported by footings below the frost level.

Do you know what a good idea is? A deck in the backyard to enjoy the outdoors.

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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