A floating deck is an excellent idea for and DIYer deck to build, but floating decks have limits regarding height and size. How high you can build a floating deck is often determined by where you live and local code but as a general rule for floating deck height.
In the United States, a floating deck’s maximum height is 30″ above grade if not attached to a house or in front of an egress door.
In Canada, a floating deck can be no taller than 24″ (0.6m) above grade.
As you can easily see, different regions have different codes regarding floating deck heights. The above to heights are good quick references. With very few exceptions, most floating decks can be as high as 30″ from the ground if you are in the United States.
In Canada, this limit is a little lower. Most Canadian floating decks can be no taller than 24″ (0.6m) from the ground.
Floating Deck Height Determine by Permits
This is related mainly to permits. If a deck requires a permit, you will need to use frost-level footings. Deleting the option of a floating deck.
“A building permit is required for construction of deck or porch that is more than 30″ above grade.”City of Austin, Texas
This is very common in almost every city deck permits checklist. If the deck is higher than, a permit and frost footings are required. Another common requirement is the size which I will get to later.
If you are a curious Canadian looking for depth of frost footings, click the link for 22 Canadian cities deck footings depths.
But this is not universal. Here are two Canadian exceptions for floating decks, both height and attachment.
Exceptions to Floating Deck Height
Winnipeg, with its deep frost footings requirements, provides an excellent alternative, floating concrete pad footings. Doing an excellent job of describing best practise for floating footings.
I would recommend going to their site if you plan to build a floating deck regardless of location. Very good pictures and descriptions of how to install floating footings that are stable and secure.
Here is the link to Winnipeg floating footings requirements.
But to our point of exception in height.
“c) not more than 1300 mm (4 ft. 3 in.) in distance from finished ground to the underside of the joist;”
In Winnipeg, Manitoba, you can build a floating deck as high as 60″ (1.524m) high. If you use 2×10 joists. Giving you many more options for floating deck locations.
With few backdoors not being low enough for a floating deck.
But one stipulation is that the deck cannot be attached to the house.
Another very common requirement of floating decks.
Most floating decks cannot be attached to your house.
Where You Can Attach a Floating Deck to Your House
In Edmonton, Alberta, their research has shown that you can attach a floating deck to the house without damaging the house.
Before you run out and start attaching a floating deck to your house check to see if the same rules apply to where you live.
If you are the lucky one living in Edmonton, please check out their complete deck requirement before building. There is more to building a deck than the deck’s height.
The link below will get you started in Edmonton.
I would like to note this again. Edmonton is very clear about drainage material under the pad. This is so important to building a stable floating deck.
How Low Can a Floating Deck Be?
On the flip side, of maximum deck height is minimum.
This is not often a code or permit question but is related to material durability.
You can use joists treated for ground contact. Allowing the deck to be at ground level or lower. But it would be best if you still provide some distance between the decking and the dirt. As most decking is not designed for ground contact.
A rare exception is MoistureShield, which is engineered both for water and ground contact.
All other decking should be a minimum of 7″ (180mm) above grade or at least of drain rock and landscape fabric under it.
Maximum Floating Deck Size
Just like height of a floating deck, maximum size depends on where you are building the deck.
So, let’s start with some general, nationwide common size restrictions and then look at some exceptions.
In the United States, the maximum floating deck size is 200 square feet.
North of the border in Canada the maximum floating deck size is 55 sq m (592 sq ft).
So more often than not, in Canada, you can build a larger but lower floating deck than in the United States.
But always check with your local jurisdiction before building.
Some are very clear of the maximum size. Many will clearly say the size of the deck that requiring frost footing and permits.
Requirement of permits often being the first clue.
With rare exceptions, Winnipeg.
If the deck requires a permit, it cannot be floating.
Also, look carefully for building requirements.
For example, Edmonton deck requirements.
“Ground anchorage is not required in Code for uncovered single-level decks up to 55 sq m (592 sq ft) in area, but highly recommended.”Edmonton Deck Code
It does not clearly say that the maximum floating deck size is 592 sq ft.
But how can you anchor the deck to the ground without frost footings?
In Edmonton, the maximum floating deck can be understood to be 592 square feet.
Your city may phrase things similarly. Please become familiar with their building requirements.
If you are ready to make it a reality. I have a full article walking step by step as I build a floating deck. Using 6×6 footings, but built to minimize movement.
Sources for Floating Deck Maximum Height and Size