Sunken patio under the deck, a gate that won't latch, a fence line stepping downhill — the concrete underneath outdoor structures settles like any other slab, but access and diagnosis make these jobs different.
It's rarely the deck itself. What's sinking is the concrete the deck sits over or lands on: the patio slab underneath a raised deck, the stair landing at the bottom of deck steps, the walkway that runs beneath it, or the small pads under deck posts. These slabs fail for the same reasons all Utah concrete fails — freeze–thaw, water erosion, poorly compacted backfill, clay movement — but decks make the causes harder to see and the symptoms easier to miss. A patio under a deck can drop an inch before anyone notices, because nobody walks on it daily. By the time the deck stairs start feeling wrong, or water starts pooling under the deck, the slab has often been moving for seasons.
Decks also create their own water problem. A deck roof and deck boards shed rain in concentrated lines, and if that water lands on the same strip of concrete or soil every storm, it erodes support exactly there. Gutters that dump beside a deck, or a deck built without drainage planning, can undermine the very slabs the deck depends on. When a contractor assesses a sunken slab under a deck, the first question should be about where the deck's water goes — not just how far the slab dropped.
Lifting equipment needs room: a pump hose, drill clearance, and space for the operator to watch the slab rise against a level. Under a low deck, that room may not exist. Three access scenarios cover most jobs:
The easy case. A deck high enough to work under, with open sides for hose access, lifts like any patio. The crew works from the sides and the slab is fully reachable. Price it like a normal patio lift.
The common case. Some sections are reachable from the sides, others aren't. The crew may lift what they can reach and leave a section, or work through gaps between boards. Ask exactly which sections the quote covers — "the patio" and "the reachable patio" are different jobs.
The hard case. Reaching the slab means temporarily removing deck boards — sometimes a few, sometimes a section. That labor belongs in the quote, along with who removes the boards, who replaces them, and what happens if a board breaks. A quote that ignores access isn't cheaper; it's incomplete.
The deceptively tricky case. The landing at the bottom of deck stairs is small, visible, and precision work — it has to meet the bottom step exactly. Foam's small holes and controlled lift are an advantage here, and the landing often lands near the contractor's $300–$500 minimum charge. Small job, high precision.
The practical rule: get the access plan in writing before job day. Which boards come up, who handles them, whether reassembly is included, and what the price is if access turns out worse than expected. Surprise access costs are the most common reason a deck-area lift goes over budget.
Fences fail differently from slabs, and the distinction decides lift versus rebuild. A fence is posts in concrete footings, and there are three separate things that can go wrong: the footing can settle (the whole unit drops), the footing can crack or break apart, or the post itself can rot, lean, or loosen in an intact footing. Only the first is a lifting candidate — and even then, lifting a fence footing is a smaller, more delicate job than lifting a slab, because the "slab" is a single post base that has to stay plumb while it rises.
The gate post is the usual casualty, for structural reasons: the gate's weight hangs on one post, that post gets worked every time the gate swings, and gate footings are often poured shallower than line posts. When a gate stops latching, homeowners assume the gate sagged — and sometimes it did — but often the post footing settled or heaved, and the gate is faithfully following a post that moved. Diagnosing the post comes before lifting anything around it: is the post solid and plumb in its footing, or rotted at grade, or loose? A solid post in a settled footing is a lift-or-reset conversation. A rotted post is a replacement, full stop, and lifting concrete around it fixes nothing.
Frost heave deserves special mention on fence lines. Utah winters jack shallow footings upward, and a fence line that steps up and down after winter is often heave, not settlement — the footing rose rather than sank. Heaved footings sometimes settle back in spring, and a contractor who wants to lift a heaved footing in February is solving a problem that spring may solve for free. Seasonal patience is a virtue on fence lines; see frost heave vs. settlement for the full distinction.
| Situation | Usually | Why |
|---|---|---|
| Patio slab under deck, settled but intact | Lift | Standard lift economics: one-third to one-half of replacement, hours not days |
| Stair landing dropped, concrete intact | Lift | Small precision job; foam's control and small holes suit visible entries |
| Fence footing settled, post solid | Lift or reset | Small-scale job; get a specific quote — not every crew does footing work |
| Post rotted, leaning, or loose in footing | Rebuild | The post is the failure, not the concrete; lifting can't fix rot |
| Footing cracked or shattered | Rebuild | Broken footings can't be lifted into integrity |
| Slab crumbling or spalling under deck | Rebuild | Same rule as anywhere: lifting rubble is wasted money |
| Access requires major deck disassembly | Price both | Access labor can narrow the lift-vs-rebuild gap; get both numbers |
One more consideration specific to decks: the deck structure itself. If deck posts sit on the sinking slab — not on independent footings — lifting the slab changes the deck's bearing. A good contractor coordinates with the deck's structure rather than just pumping under it, and if the deck posts themselves have settled, that's a deck contractor's conversation, not a concrete lifter's. Know which professional owns which part before anyone starts.
Under-deck slabs price like the patios and walkways they are: a patio-sized area (~200 sq ft) runs $500–$1,000 mudjacking or $1,200–$2,400 foam, and small landings often land near the $300–$500 minimum. Fence footing work is quoted case by case — it's not on the standard price table, so get a specific written number rather than extrapolating from slab pricing. The full published tables are in the cost guide. Before hiring for deck or fence work, ask:
Those questions, plus the access plan in writing, are what separate a clean deck-area job from a frustrating one. And if the answer to any of them is a shrug, how to choose a contractor has the wider checklist.
Often yes — patio slabs and stair landings under decks are standard lift jobs. The constraint is access: the crew needs room to work the pump hose and drill, which can mean temporarily removing deck boards or working from the sides. A contractor should assess access before quoting, not after arriving.
It depends on what failed. A concrete footing that has settled as a unit can sometimes be lifted, but a rotted post, a cracked footing, or a footing that has heaved from frost is usually a rebuild — new post, new footing — not a lift. A good contractor will tell you which one you're looking at rather than lifting something that needs replacing.
Lifting is almost always cheaper — typically one-third to one-half the cost of tearing out and re-pouring. The exception is access: if reaching the slab requires major deck disassembly, the access cost can narrow the gap. Get the access plan priced in the quote, not discovered on job day.
Gates concentrate stress: the weight of the gate hangs on one post, that post gets worked every time the gate swings, and gate footings are often shallower than line posts. Add frost heave or clay movement and the gate post is the first to show it — usually as a gate that won't latch.
Sometimes — if the problem is a settled concrete pad or footing under the gate area, lifting it back to grade can restore the latch. But if the post itself is rotted, leaning, or its footing is broken, lifting the surrounding concrete won't fix the post. Diagnose the post before lifting anything around it.
Sometimes a few boards, sometimes none — it depends on clearance and where the low spot is. Ask the contractor during the assessment: which boards, who removes and replaces them, and whether that labor is in the quote. Don't let access become a surprise line item.
Describe the slab, the access, and the structure above it — a local specialist will tell you whether it's a lift, a reset, or a rebuild.