My deck has moved!

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swimmer_spe

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Along our house, during the winter, the deck was very close to the house. Now, there is a good inch of a gap. The deck is huge; about 50'x30'. It isn't attached to the house and is sitting on deck blocks. Should I be concerned or is this a normal thing for a free floating deck?
 

oldognewtrick

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Has anything changed to the supporting ground the blocks are on? Did you check to see if there's an issue at the post base, wood rot or block sinking?
 

bud16415

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Do the checks oldog mentioned.

I have a free standing floating deck with a 6000 hot tub sitting on it on deck blocks and I have seen some movement between winter and summer as well. I have looked everything over close and I feel it is normal and not overly worried. My ground is mostly level at the surface and posts are not too long, just a normal grading away from the house. If your deck has tall posts or is built on a big slope then I would be checking plumb and level as well.
 

swimmer_spe

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Has anything changed to the supporting ground the blocks are on? Did you check to see if there's an issue at the post base, wood rot or block sinking?
As far as I can see, nothing has changed. Blocks haven't moved or sunk, no rot, or anything else.

Do the checks oldog mentioned.

I have a free standing floating deck with a 6000 hot tub sitting on it on deck blocks and I have seen some movement between winter and summer as well. I have looked everything over close and I feel it is normal and not overly worried. My ground is mostly level at the surface and posts are not too long, just a normal grading away from the house. If your deck has tall posts or is built on a big slope then I would be checking plumb and level as well.
Good to know.
 

Jeff Handy

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If your deck is moving around, it was built wrong from the start, it should be attached to the house.
With adequate supporting structure going down below frost level.

You gave no info as far as your location, weather, height of deck, condition of subsoil.

Safe to assume your deck is moving from either frost heave, sinking of deck blocks into soft soil, or poor engineering, which sounds like the main culprit.

Depending on your climate and your soil, the deck blocks might be a poor base for a huge platform like that.

Think of your deck as a big tarp, just laying on dirt.
 

Steve123

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Deck does not necessarily have to be attached to the house.

A floating deck would be required to have independent footings down to below the frost line. Very valid and many would call it preferred to attaching with a ledger board to house.

But if you live where you have a frost line, sitting on deck blocks is not proper support, and likely was never permitted and inspected.
 

swimmer_spe

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Deck does not necessarily have to be attached to the house.

A floating deck would be required to have independent footings down to below the frost line. Very valid and many would call it preferred to attaching with a ledger board to house.

But if you live where you have a frost line, sitting on deck blocks is not proper support, and likely was never permitted and inspected.
It is on deck blocks. I am thinking it was never inspected as well. The inspector we hired to do a home inspection for the sale pointed out deficiencies with the deck's structure.

We are planning an addition to the house in about 5 years. The deck would be rebuilt at that time.
 

bud16415

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In my case the house is close to 150 years old and balloon framing. I figured the odds of attaching to the house with a ledger and getting it solid without a lot of exploration wasn’t a good idea, even though I see many done that way. My frost line is a good 48” and adding posts next to a field stone wall also seemed questionable.



I started asking around because the height was going to be low what zoning would say about free standing and floating and the answer is floating on pre-cast footings was not considered a permanent structure.



I decided to give it a try and the shallow laid pre-cast footings lock right in with the first freeze and go up and down with the ground. I made the deck spaced from the house 1” and 2” step down from the doorway. It has floated now for at least a half a dozen years and has seen temps as low as –35F. I watch it winter and summer and it lifts half inch in the winter and I see a little side to side, but it always comes back pretty much to the start point.

I don’t see the real problem with a low floating deck and I would do it again.
 

mabloodhound

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Free floating decks are the preferred method as opposed to using a ledger board. What Bud said makes sense.
 

Jeff Handy

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Free floating deck is limited to 30 inches from the ground in most codes.
In Canada, 24 inches.
Some jurisdictions limit deck size to 200 square feet.
So the OP’s deck of 1500 square feet is ridiculous.
 

Steve123

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Free floating deck is limited to 30 inches from the ground in most codes.
In Canada, 24 inches.
Some jurisdictions limit deck size to 200 square feet.
So the OP’s deck of 1500 square feet is ridiculous.

I don't think you understand what a floating deck is., or at least how the term is being used here. Let us call it a free-standing deck.

Instead of attached to the house on one end, and a number of sonotubes (to below the frost line and to undisturbed soil) on the other end, a free-standing deck will have a number of sonotubes close to the house and a number of sonotubes on the other end. No connection to the house at all. The deck is fully independent to the house.

The reason it is preferred, particularly for a tall deck, is that the number one reason for catastrophic deck failure is the ledger board pulling away from the house. The other problem frequently encountered is needing to attach a ledger board to brick. The brick on homes here is not structural -- it is a protective veneer. There is a one inch gap between the brick and the framed structure. A ledger attached to brick is not a proper connection.

The difficulty being that besides needing to go below the frost line, the deck footing need to go to undisturbed soil. When the house was built, if in a northern area with a basement, the foundation pit was dug to the house footings (perhaps 7 feet deep) and the soil within a few feet of the wall is all disturbed soil all the way down to the footings. My last house was a raised ranch, so when we built my free-standing deck, the footings close to the house had to go down about 5 or 6 feet -- not a big deal.
 
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Jeff Handy

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The ledger board provides support for the deck framing, near the house.
There is no need to dig footings right next to the house, in soil disturbed during construction.
The footings are dug in undisturbed soil, farther away from the house.
The ledger board framing system is almost like a cantilever that is not free hanging, but is held up by the house frame or foundation.
The house is sitting on undisturbed or compacted soil.
 

swimmer_spe

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OP here.... sounds like my deck was not built to code.....
Great! I'll add it to the list of things not built to code around here.
 

bud16415

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OP here.... sounds like my deck was not built to code.....
Great! I'll add it to the list of things not built to code around here.
It might not be a deck at all. It might just be a big platform you have sitting by your house that could be moved at any time.
 

cdestuck

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I would be at least attaching this to the house in some manner. What I would do and have done in the past is drill through the joist of the deck next to the house and go through the rim joist Of the house. Get some three-quarter inch all thread and bought this deck to the house at about every 6 to 8 feet
 

Eddie_T

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I would just ignore it until you get into the addition five years down the road. If the gap becomes a problem just cover or fill the gap. Unless codes prevent it in your area a floating free standing deck can save some big bucks.
 

swimmer_spe

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I would be at least attaching this to the house in some manner. What I would do and have done in the past is drill through the joist of the deck next to the house and go through the rim joist Of the house. Get some three-quarter inch all thread and bought this deck to the house at about every 6 to 8 feet
I don't want to get a permit only to find out that there is much, much more needed to bring it to code. My home inspector pointed out replacing the structure of the deck as it may not be to code.

I would just ignore it until you get into the addition five years down the road. If the gap becomes a problem just cover or fill the gap. Unless codes prevent it in your area a floating free standing deck can save some big bucks.
Before winter, I'll be jacking up the other end and somehow supporting it better so that next year it doesn't open more.
 
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