Titan Deck Foot & Freeze Thaw Cycles

by Dean
(Edmonton)

I live in Edmonton and I'm wondering if the 2' Titan Deck foot is sufficient in our area due to the depth of freezing over the winter.

I'm building a 14'x 21' deck this spring with 6 - 8 posts.

Will the deck foot anchor perform suitably with a clay base.

Would the 3' be a better option.

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Apr 13, 2013
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starstarstarstar 		Why use a 24" over 36" Rod
by: Editor-Rich Bergman

Great questions. Here is a visual animation of how the deck foot behaves in freezing soil. As you can see, regardless of the length of the auger, the deck will rise up and down annually with soil freeze (expansion) and thaw conditions.

Here is the deck foot with a 24" auger.

Deck Foot anchor in frost

And here is the deck foot with a 36" auger.

Deck Foot anchor in frost

You will notice that regardless of whether the helical blades are inside or below the frost line, the large surface area of the load plate resting on the surface means anything resting on the soil will rise and descend annually as if it were on an elevator platform.

Many people seem to think that the Titan Deck Foot will resist frost heave which is an expansion of the soil due to water freezing in the soil.

The Deck Foot is very securely screwed into the ground. It can take thousands of pounds to pull out. However, its large surface area load plate means the underside of it is exposed to the immense upward forces generated when water freezes and the soil expands.

So although your eye can not detect frost heave - unless you mark a height on a nearby house foundation before freezing - and then read it during the winter - the Deck Foot will rise up and drop down over the winter season.

There is nothing to fear from this. Unless you attach your deck to the house. And so the Deck Foot must never be used for ledger attached decks.

Typical movement which we have measured over a winter period in moist clay soil is 1/2". This is imperceptible unless you measure accurately.

So ask yourself if you must have a ledger attached deck and if so you will have to use a different deck footing system like concrete below frost level or an engineered helical pier produc. All of these are much much more expensive.

There is no measured benefit to resistance of frost heave from using a longer anchor rod. In fact the longer the rod the greater chance you will strike a rock during installation.

The only possible benefit is if you are installing in very soft soil like dry sand where the pullout resistance will be at its lowest. A longer rod may help increase pullout because of the increased weight of soil above the helixes.

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What about Frost Zones and Floating Decks

by John
(Michigan)

Please advise whether your Titan Deck Footings can/should be used in freeze zones where the frost line is 4 feet below grade.

I will be constructing a detached deck at my home this summer, and prefer your design to deck blocks, but the issue of the freeze/thaw cycle is not addressed in your literature.

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Apr 09, 2022
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starstarstarstarstar 		hhh NEW
by: Anonymous

ff
Apr 29, 2012
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starstarstarstar 		Deck will float with the soil
by: Editor - Rich Bergman

The Deck Foot system is a floating footing system even though it is firmly anchored into the ground. This means the entire deck, securely attached to the footings will move along with the annual movement of the soil. This is how decks using concrete deck blocks work. And it is how decks using ground spikes with adapted load plates work.

The anchor is well within the frozen zone of earth and when it freezes water will expand and if there is enough water in the soil you can expect to see these areas rise about an inch or so. When the frost melts the deck drops down again to where it naturally rests. This can happen every year and is almost imperceptible unless you marked lines on the house to record starting and ending elevations.

The key difference between a fence post or concrete pier "popping" up in the winter and staying there in the spring time is because the bottom of the post or pier has a large surface area and if ice is below it will push up on all the surface area. In addition ice can grab the sonotube or the wood post walls and grip tightly and also act to lift it up. But once the ice in the soil begins to melt the reverse is not true.

The watery slurry of muck drains down to fill the gap under the bottom of the post or pier preventing the post or pier from settling back to normal. Each year this happens a bit more and more. You see the post go higher and higher above ground each year.

But this doesn't happen with anchors that have pointed ends like spikes or screw like anchors given the surface area is so small along the sides of the anchor tube or at the point of the anchor. It remains stuck in the icy soil and moves in unison with it.

It is possible that frost can loosen the initial tight grip of a ground spike or a helical anchor if you were able to get close and check it. But the weight of the entire deck structure remains on top pushing down. The footing is not "popped" up each year like a fence post or pier that was not installed below frost level.

So what you end up with is the structure sitting in the same place annually relative to the soil. Structures like this must not attach to another structure that has a deep footing below frost as any ledger connection or the like can be ripped away from the forces of the uplift.

A floating deck also should not go much higher than about 6' above grade and should have bracing between support posts and beams to keep it from wobbling. This is easily done.

The deck structure you see on the information page is mine. And we have snow every winter and a 48" minimum frost line. The deck also has a lot of extra snow piled on it as we clear a path for access to a hot tub. We had zero movement this year even though there was snow. But I think that is because this winter was a particularly mild winter. I designed it to allow for some movement free of the house.

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