Deck Pulling Away From the House: What Actually Moved
What this comes down to
- A visible gap at the wall means the connection has already failed, not that it is about to.
- Look at the far end of the deck first. A dropped outer edge means the footings, not the ledger.
- Nail heads pulling straight out are withdrawal. Bent nails mean the deck dropped instead.
- Some decks are built freestanding on purpose, and a gap on one of those is not a fault.
- Rot in the house band joist opens a gap long before it shows as a stain on the siding.
- Keep people off a deck with a gap. Deck connections fail under load, not while empty.
A deck pulling away from the house is not a cosmetic problem. The gap is the connection letting go. Something has moved, and the only useful question is which end of it moved first.
It can be the ledger, the fasteners, the band joist behind them, or the footings under the posts. All four look much the same from the yard. All four cost something very different to put right.
What does a gap at the wall actually mean?
It means the connection has already failed, not that it is about to. A deck ledger is meant to sit tight against the house. Any daylight between the two is movement that has already happened.
The American Wood Council's prescriptive deck guide sets out how ledgers should attach. A two by eight minimum, bolted or lag screwed into the house band joist. Nails are not on that list at all.
The International Code Council makes a further point. Every code edition since 2000 has required a deck to be anchored against lateral load. A gap says that anchorage has stopped working.
Did the deck move, or did the posts sink?
Look at the far end of the deck before you look at the wall. If the outer edge has dropped and the wall end has not, the footings moved. If the wall end has opened and the deck is still level, the ledger moved.
Footings are the quieter cause. A footing poured above the frost line lifts a little every winter and settles every spring. After enough cycles the posts are no longer the height they started at.
That movement drags the whole frame around with it. The deck tilts and the stairs stop meeting the ground squarely. The gap at the house opens because the far end is now hanging off the ledger.
How do you tell which end failed?
Five checks separate the causes, and none of them needs a tool. Each one reads a different part of the frame. Together they point at either the wall end or the ground end of the deck.
- The fastener heads. Round heads pulling straight out mean the ledger is withdrawing.
- The shape of the gap. Even top to bottom is withdrawal. Wider at the top means a drop.
- The deck surface. A level deck with a gap points at the wall. A sloped one points at the posts.
- The bottom step. A step that has grown taller says the deck itself came down.
- The siding above the ledger. Staining or soft trim says the band joist has been wet for years.
Two of those five point at the house rather than the deck. A soft band joist is a structural repair before it is anything else. Rebolting into soft timber would achieve nothing at all.
Is it safe to use while you wait?
No, and this is one of the few places where a blunt answer is the right one. A ledger that has moved once carries less than it did. The failure mode is sudden and it arrives under load.
Simpson Strong-Tie makes tested tension ties for this exact connection. Two of them, each sized for a 1,500 pound lateral load, is what the code expects a deck to carry.
Until somebody has looked, keep people off it. Move the furniture and the grill, and host nothing on it. A deck fails when it is loaded, which is the one moment everybody is standing on it.
Was the deck ever attached at all?
Some decks are built freestanding on purpose. They carry their own weight on a beam and posts set near the wall, with no ledger at all. A gap on one of those is normal rather than a fault.
Freestanding is the usual choice where a ledger cannot be flashed properly. It is also what a builder picks on brick veneer. Or when the band joist is not sound enough to bolt into.
Telling them apart takes one look underneath. A ledger deck has a board fixed flat against the house. A freestanding deck has a beam and its own posts sitting a few inches clear of the wall.
What does each cause cost to put right?
The price follows the cause, not the size of the gap. Rebolting a sound ledger into a sound band joist is a day. Replacing a wet band joist means taking the siding off first.
| The work | Starting price | Wider market | What moves it |
|---|---|---|---|
| Ledger board repair and re-bolting | 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 |
| Joist repair or sistering | From $125 per joist | $150 to $350 each | How many joists, and whether the decking has to come up |
| Deck stair repair after movement | From $225 | $250 to $750 | Whether the stringers moved with the deck or stayed put |
| Full stair rebuild | From $795 | $900 to $2,500 | Rise and run changing once the deck is back to level |
| Typical 12x16 deck, 192 sq ft | From $4,495 | $4,700 to $9,300 | Whether the old deck and its footings come out first |
The North American Deck and Railing Association counts more than 60 million decks in use here. An estimated 30 million of them are already past their useful life. A gap is often the first sign of it.
What cannot be determined from the yard?
The state of the house band joist. It sits behind siding, sheathing and the ledger itself. Confirming it means taking off a course of siding and looking at the timber.
How deep the footings actually go. Nothing at grade shows the depth of the concrete. A footing that heaves every winter looks identical to one that never moves.
Whether the fasteners reach anything. A lag screw stopping inside the sheathing looks the same from outside as one passing right through.
Perfect Work checks these before quoting rather than after. That is why the estimate arrives with the unknowns named instead of buried inside a round number. Having them checked costs nothing.
Questions about a deck that has moved
How big does the gap have to be before it matters?
Any visible gap matters, because the ledger was installed tight to the wall. A quarter inch is enough to say the connection has moved. Anything you can slide a pencil into takes the deck out of use until somebody has looked at it.
Can a deck be pushed back and bolted again?
Sometimes, if the ledger and the band joist behind it are both sound. The deck is jacked back into position, flashed and bolted with through bolts or lag screws. If either member is soft, bolting into it just repeats the original failure.
Why would a deck pull away if the wood still looks good?
Because the fasteners can fail while the timber stays sound. Nails withdraw and undersized lag screws bend. Screws that never reached the band joist were holding sheathing all along. Sound timber tells you nothing about the steel buried inside it.
Does a deck pulling away mean the house has a problem?
It can. If the gap traces back to a soft band joist, the problem is in the house frame. The deck revealed it. If it traces back to the footings or the fasteners, the house is fine and the deck is the whole job.
Will a permit be needed to fix it?
Usually yes, once structural members are replaced. Most DuPage County towns treat a new ledger, new footings or a new frame as permit work. Bolting and flashing a sound ledger often is not. The building department settles it in one call.
How long does this kind of repair take?
Re-bolting and flashing a sound ledger is a day. Replacing a ledger runs to two or three, because the siding comes off and goes back on. New footings add a week, since the concrete has to cure before anything is loaded onto it.
Getting a straight answer on a deck that has moved
The first job is deciding whether this is a deck repair or a house repair. That answer changes the price more than anything else. It cannot be settled from a photograph of the gap.
An inspection means probing the ledger and the band joist. Then the fastener pattern, then a level across the deck. Nearby work runs through deck repair in Naperville and the same in Wheaton. Everything else sits on the full service list.
Findings come back plainly. What moved, what has to be replaced, and which part of it is not a deck job at all. Then a number for the work, given before anything is taken apart.
Perfect Work Remodeling & Repairs covers a deck that has moved across DuPage County. The office is in Carol Stream. The crew that assesses the work is the crew that does it, with no subcontractors in between.
Perfect Work Remodeling & Repairs · 630-297-7888 · Book a deck check