Should You Repair or Replace Your Deck? The Frame Decides
Before you decide
- Deck boards are the least costly part of a deck and the worst guide to replacing one.
- The frame decides. Ledger, posts, footings, beam and joists are where the money goes.
- A ledger held by nails alone is the most common reason a deck comes off a house.
- Rot needs timber that stays wet. Wood which dries between rains does not decay.
- Past about half the cost of a rebuild, the rebuild returns better value.
- Nothing under the decking or below grade can be priced until it is opened up.
Almost everyone judges a deck by its boards. They are what you stand on, and they gray, cup and splinter first. They are also the least costly part of it to put right.
The decision is made underneath. A deck is a frame carrying a walking surface: ledger, posts, footings, beam and joists. Boards can be replaced over a sound frame. A failed frame cannot.
What are you looking at when a deck looks past it?
Gray, splintered boards are a surface condition, not a structural verdict. Pressure-treated timber weathers to gray within a season or two. Boards are consumable, and replacing them over sound framing is routine.
What matters is whether the frame beneath them is still doing its job. A deck that feels solid under ugly boards is a repair. A deck with tidy boards that moves underfoot is not.
Which part of a deck decides the answer?
Five parts of a deck carry the load, and each of them fails differently. The list runs in order of consequence. That is close to the reverse of the order most people inspect in.
- Ledger. The board fixed to the house. It carries roughly half the deck load.
- Posts and footings. Below grade, out of sight, and the part that settles.
- Beam. Spans between posts and carries the joists. Failure here is rarely local.
- Joists. Carry the boards. Rot starts on the top edge, under the decking.
- Boards and railing. The wearing surface and the guard. Both come off on their own.
Damage that stops at the boards and railing is a repair, every time. Damage in the ledger, the posts or the footings changes the arithmetic. Reaching any of them means taking the deck apart.
How do you tell if the ledger is the problem?
Look at the face of the ledger where it meets the house. Bolt or lag screw heads at regular spacing mean the deck is fixed to the structure. Nail heads alone usually mean it is not.
That is not a detail. The American Wood Council's guidance on how ledgers should attach is blunt about the risk. Collapses most often follow ledger connections built with nails instead of bolts.
The other thing to check is flashing. Metal flashing over the ledger keeps water off the house band joist behind it. Without it, that band joist has been wetting for as long as the deck has stood.
How far has the rot actually gone?
Rot needs sustained wetness, which is why it turns up in the same places on every deck. Timber that dries between rains does not decay. Timber trapped against another surface, or sitting on soil, does.
The threshold is specific. Serious decay runs only above the fiber saturation point of the timber. The USDA Forest Products Laboratory puts it at an average of about thirty percent moisture. Air-dried timber under twenty percent carries a reasonable margin.
So probing beats looking. A screwdriver pushed into sound timber stops. Pushed into decayed timber it sinks with almost no pressure. Probe the joist tops, the post bases and the stair stringers.
Rot that has spread into the house band joist becomes structural rot repair. It is priced as that rather than as deck work. It is also the point where a deck problem becomes a house problem.
What about the posts and the footings?
Footings are the part nobody sees and the part that decides whether a rebuild is avoidable. They sit below grade and carry everything above them. When they move, every measurement above them moves too.
A deck that has dropped at one corner is usually sitting on a footing that has moved. Stairs pulling away from the frame point the same way. Frost does this over years, not over one winter. Post bases fail differently. A post on soil, or on a pad that holds water, rots from the bottom up.
Both are replaceable, and neither is a small job. Both mean holding the deck up while the work happens. That is why either one moves a job toward the cost of a rebuild rather than a repair.
Do the fasteners matter as much as the timber?
They do, and they are the part of a deck almost nobody inspects. Some modern preservative treatments are more corrosive to steel than the older one they replaced. Fasteners chosen for the older lumber fail early in the new.
Simpson Strong-Tie recommends hot-dip galvanized or stainless hardware outdoors. The two should not be mixed. On an older deck the giveaway is rust streaking below every fixing. That hardware is replaced during a repair, not treated as a reason to replace the deck.
What can be repaired?
Most of what a homeowner notices, provided the frame is sound and the footings have not moved. The work below restores a deck without dismantling it, which keeps it inexpensive.
- Gray, cupped or splintered boards, replaced over the existing frame
- One or two soft joists, sistered with new timber alongside
- A nailed ledger, re-bolted to the band joist and flashed properly
- A settled or rotted post, replaced on a new footing
- Loose or bouncing stairs, with stringers and treads renewed
- A wobbly railing, refixed to the posts or replaced
All of that is routine deck repair work rather than a rebuild. A handful of loose boards and a rail that moves are smaller still. Those fall under work charged by the hour.
What points to replacement?
Replacement becomes the honest answer when the frame itself has failed. It also applies once the failures stop being isolated. One bad joist is a repair. Six bad joists is a frame with a drainage problem.
- Footings that have settled or heaved, leaving the deck out of level
- A beam split, sagged or rotted where it sits on the posts
- Rot in the house band joist behind the ledger
- Joists soft along most of their length rather than at one end
- A frame built to spans the timber will not carry
- Repairs adding up to more than half the cost of a new deck
The last one settles most cases. It is not a rule of thumb about age, and not about how the deck looks from the kitchen window. It is arithmetic, and it is done before any work starts.
What does each option cost?
The figures below are starting prices rather than quotations. The middle column is the wider Chicago-area market, for scale. The last column is what moves a job within its range.
| The work | Starting price | Wider market | What moves it |
|---|---|---|---|
| Board replacement over a sound frame | From $10 per sq ft | $12 to $25 / sq ft | Board material, and how many joists need attention |
| Typical 200 sq ft re-deck | From $1,995 | $2,400 to $5,000 | Whether the railing is reused, and the state of the joist tops |
| Joist repair or sistering | From $125 per joist | $150 to $350 each | How many joists, and whether the decking comes up |
| Joist replacement | From $175 per joist | $200 to $450 each | Span, access underneath, and whether hangers can be reused |
| Ledger board repair | From $495 | $600 to $1,500 | Missing flashing, and the state of the band joist behind |
| Ledger replacement or major repair | From $695 | $800 to $2,500 | Whether the siding comes off, and what is behind it |
| Typical 12x16 deck, 192 sq ft | From $4,495 | $4,700 to $9,300 | Whether the old deck and its footings come out first |
Two numbers do most of the deciding. A re-deck over a sound frame starts at $1,995, and a comparable new deck starts at $4,495. That gap is the whole question in one line.
When does repair stop being worth it?
At roughly half the cost of a rebuild, and the reason is service life rather than money. A repair restores the parts that were replaced. A rebuild resets the clock on all of it.
Spend $2,600 on joists and a ledger under a tired frame and the rest of it is unchanged. Spend $4,495 on a new deck and all of it is new. The second is better value despite being the larger number.
Below that line the arithmetic reverses. A deck needing boards and two joists is nowhere near half the cost of replacement. Replacing it would be waste. Homeowners describe how that conversation went in their own words.
Does deck work need a permit in DuPage County?
That depends on the municipality, and on how much of the structure is being replaced. A house in unincorporated DuPage answers to the county. A house in Wheaton or Naperville answers to its own building department.
For county work, DuPage County Building and Zoning sets out what a permit needs in one place. It asks for a plat of survey showing the deck to scale, with distances to the lot lines. It also asks for a construction plan with a cross-section and a top view.
The county's sample cross-section shows a footing set well below the frost line. That drawing is not the number for a particular property. Depth, fee, and whether a repair needs a permit at all are confirmed with the issuing department.
What cannot be determined until the decking comes up?
Three things, and they are the three that move the price most. Saying so is not hedging. It is the limit of what anyone can establish while the boards are still screwed down.
The top edge of every joist. Water sits between the boards and the joists beneath. A joist can be sound underneath and soft along the top. That face stays invisible until the decking lifts.
The band joist behind the ledger. It sits behind siding and flashing, so confirming its condition means removing a course of siding. That takes minutes, but not from the driveway.
What the footings are sitting on. Depth and bearing are below grade by definition. A level deck has footings that have held so far, which is evidence rather than proof. A price quoted before all three are checked is a guess.
Frequently asked questions
How old does a deck have to be before it needs replacing?
Age on its own decides nothing. A twelve-year-old deck with rotted footings needs replacing. A thirty-year-old deck on a dry, well-drained frame may not. What matters is whether the frame still carries load safely.
Can new boards be laid over old decking?
No. Laying new boards over old ones hides the joists when they most need looking at. It also adds weight to a frame nobody has checked. Old boards come off, then the frame is inspected.
Is a bouncy deck dangerous?
Bounce is a stiffness problem rather than a strength problem, but it is worth investigating. Joists spanning further than the timber comfortably allows will flex. Joists that flex more than they used to have lost material to rot.
Does a repaired deck have to meet current code?
The repaired portion generally does. The answer sits with the municipality rather than a contractor. Replacing a railing usually means meeting current height and spacing rules. Confirm the locally adopted edition before work starts.
How does Perfect Work decide between repairing and replacing a deck?
Perfect Work Remodeling & Repairs lifts boards before quoting rather than after. The joist tops, the ledger, the post bases and the footings are checked. The scope is written down first. A deck that can be repaired is quoted as a repair.
Getting a straight answer on your deck
An assessment covers the frame, not only the surface. Boards are lifted where the joists need to be seen. The ledger, the post bases, the footings and the stairs are all checked.
What comes back is a written scope of work. It says what is sound, what is not, and what could not be confirmed. The work is done by a second-generation carpentry crew, with no subcontractors.
There is no charge and no obligation. The inspection is free with a repair estimate. Perfect Work is your perfect work. Call 630-297-7888 or request a deck assessment.