Deck Repair Cost Calculator

Search for what a deck repair costs and you get a range per square foot. It is the wrong answer to the right question. Nobody types that phrase wanting a rate — they type it standing on a deck with something wrong underneath, wanting to know whether to fix it or replace it. A rate cannot settle that, because the two halves are not even priced in the same unit: boards by the board, a new deck by the square foot. One number in one unit cannot tell you where they cross.

So this page computes both halves. The repair comes from the panel above. The replacement is the deck cost calculator's own figure — the same function, imported rather than copied, so the two pages cannot drift apart: $1,473 of materials, $4,224 of build labour, and $1,440 to tear the old deck off and haul it away — $7,137 in all, on our own survey prices rather than quotes.

That last item is there because you cannot build a new deck where an old one is standing. It was missing when this page was first built, and leaving it out flattered the replacement at the repair's expense. Two figures from two different sources cannot honestly be set against each other, and most of the ones you will find online were.

Replacing a third of the boards on this deck is $572. Doing everything short of rebuilding it — every board off, the joists and posts you can see put right, the railing renewed — is $5,810, against the $7,137 the whole deck costs to tear off and build new. Four fifths of the price, on the same survey estimates, for a deck whose frame you have already had.

Between those two numbers the cost does not creep. It steps.

Boards alone is $572, or 8% of a replacement. Add a few joists to sister and it roughly doubles to $1,368, because now somebody is working underneath the deck rather than on top of it. Add a post and its footing and it is $1,928 — still comfortably a repair at 27% of starting again. All three are survey estimates rather than quotes.

Then the railing — the guard, in the language of the code, and the subject of its own calculator. Adding it takes the job from $1,928 to $4,728: one item, $2,800, and the point at which the total crosses from a quarter of a new deck to two thirds of one, on the same survey estimates. Whether the railing is coming off is the decision that settles whether you are repairing this deck or rebuilding it.

Which is why the honest answer to what a deck repair costs is a question back: how far down does it go? Nobody can price that from a photograph, and nor can this calculator until you have pulled some boards and told it.

The trade rule of thumb is about half. Past roughly 50% of the cost of a replacement, the advice goes, rebuild instead — you get a full-life deck built to current code rather than a patched one of unknown remaining life. On this deck that lands near $3,569, on survey estimates.

Take that for what it is. It is not in a code, not in a standard, and nobody measured it. There is no meaningful difference between a repair at 49% and one at 51%, and the curve above is the better guide — you can see where your own scope lands rather than being told which side of a line it is on.

What the rule of thumb is really pointing at is not the money. It is that a late repair is a rebuild in disguise: you are putting a new deck together in place, around a frame that is already there, with worse access than an empty site and none of the choices a new build would give you about size, height, board or material. You pay most of the price of a new deck and get none of the decisions. That is the cost the percentage does not show.

Rot follows water. That one fact is why a deck repair cannot be priced from a photograph.

A soft board is almost never the problem. It is where the water was, and the water was also in the joist under it, in the gap where two boards butt over a joist, and behind whatever flashing was meant to keep it out of the house. From above you are looking at the symptom. The problem is between the boards and the ground. That is why the panel marks which of your own line items usually mean something worse underneath — sistering joists and resetting posts both qualify — instead of warning about everything equally.

Pull a few boards in the worst area before you commit to anything. It is an hour with a pry bar and it is the whole difference between an estimate and a price. Budget a spare board while you are at it: one that has been down for years rarely comes up cleanly.

And treat a firm quote given without opening the deck as either padded or about to rise. A contractor who has not looked underneath is guessing as much as you are — the only questions are which way, and who pays for it.

There is one part of a deck this calculator will not price, and it is the part most likely to matter to somebody reading a page about repairs. The ledger is the board that bolts the deck to the house, and it is the connection that fails all at once rather than gradually — the rest of a deck sags, splits and complains first, and a ledger lets go. Failed flashing above it is also the most common cause of the rot you can see from the surface, so anybody who has found soft boards near the house has a specific reason to have it looked at.

Finding a bad one does not add a line to the job. It changes the job. That is why there is no figure for it anywhere on this site, and why the operation that used to price it was taken out of our data rather than left in with a caveat.

What to have looked at: the flashing above it, whether it is bolted or nailed, the condition of the fasteners, and whether there is rot in the band joist behind it. That is a list, not a diagnosis, and this page is not in a position to make one — so take it to AWC DCA 6, which is free to download and is the document that governs it, and to your building department.

Old pressure-treated lumber cannot be burned. The preservative that kept it from rotting goes into the smoke and stays in the ash, and neither is something you want in a garden or a fire pit. Many transfer stations charge extra to take it and some will not take it at all, so ask yours what it does before you load anything up. That is as true of nine boards as of a whole deck.

The money side depends on the scope. We hold $350 to $700 for a dumpster or transfer station run — a survey estimate rather than a quote — scoped to a deck actually coming off. So the panel quotes it when you are stripping the whole surface and declines to when you are not: stretching a whole-deck figure across nine boards would be inventing a number.

Note which side of the comparison it sits on. The replacement figure includes hauling the old deck away; the repair total includes no skip at any scope. At full strip, the comparison is flattering the repair by roughly that much.

Pulling boards is easy. Working out what is wrong underneath is not, and that is the part the saving actually rests on.

The default job here is $572 hired out and $230 in materials if you do it yourself, about 4 hours of work on our own survey figures. Strip every board instead and it is $1,654 hired against $666 of materials and something over 10 hours — also estimates, and they assume the diagnosis was right.

That last clause is the whole risk. The skill in a deck repair is not carpentry, it is deciding what needs doing, and the failure mode is not a wonky cut. Sistering a joist that needed replacing costs the whole job twice — once now, and once when it comes back.

One gap before you trust the DIY total. Nothing on this site prices stair stringers and treads; the deck stairs calculator produces a cut list rather than a cost. So a rebuilt flight reads "Not priced" rather than $0, and the DIY total is short by whatever the timber costs you. Better to say a figure is missing than let a zero imply it is free.

• Anything about the ledger, in dollars. The section above says why. AWC DCA 6 and your building department, and no figure from us.
• What size the framing should be. Replaced joists are priced at the size already there. Whether that size suits the span is a question this site does not answer yet, and like for like is not the same as correct — a deck can have been under-framed from the day it was built.
• Whether a joist wants sistering or replacing. Both are priced — $199 and $269 each on survey estimates — but which yours needs is a judgement made looking at it.
• Whether your deck is safe. Nothing here is a determination about a structure. This page prices work; it does not inspect.
• Anything that is not a rectangular, ground-level deck. Multi-level decks, wrapped stairs and built-in benches all change the labour, and none of it is here.

The deck underneath all of it — 192 sq ft, 26 board rows, 13 joists and 3 posts on a 16 × 12 ft (4.9 × 3.7 m) deck — comes from the same function the deck calculator, the deck lumber calculator and the deck screw calculator use. The build fails if the four ever disagree.