Melbourne-wide
Expansion & Control Joint Sealing in Melbourne
Concrete moves — joints are how a structure copes with it, and sealant is what keeps those joints watertight and protected. Gapless seals expansion and control joints in slabs, warehouse floors, walls and pavements with the sealant class the movement and traffic actually require.
Understanding joints
What's the difference between an expansion joint and a control joint?
An expansion joint is a full-width gap that lets separate sections of concrete move independently without crushing each other. A control joint is a shallow groove formed or cut into a slab so shrinkage cracking happens along that line instead of at random. Both need a flexible sealant to keep water and debris out while the joint keeps moving.
There's also a construction joint — simply where one concrete pour stopped and the next started. All three get sealed for the same reason, but the sealant has to cope with very different amounts of movement. Expansion joints commonly need a sealant rated to around ±25% movement, sometimes ±50% on larger structural gaps; a slab's control joints move far less, and a construction joint may move barely at all once the concrete has cured.
Sealant depth follows joint width, not the other way around. The usual rule of thumb is roughly a 2:1 width-to-depth ratio, with a practical minimum sealant depth of about 6 mm even in narrow joints. Backer rod — a closed-cell foam rod pushed in ahead of the sealant — sets that depth and stops the sealant bonding to the base of the joint, which is what causes early tearing (three-sided adhesion). Get the ratio wrong and even a good sealant fails early.
On the engineering: where a project has an engineered joint specification, that spec sets the sealant, movement class and dimensions — we install to it. Our director's background is in civil/structural engineering, which helps in reading those specs and sizing joints correctly, but we're not registered engineers and don't issue engineering sign-off; that stays with your project engineer.
Joint sealing we do
Warehouse & factory floors
Traffic-rated sealants that protect joint edges from forklift wheels and keep floors cleanable.
Slabs, driveways & pavements
External joints sealed against water — the cheapest protection a slab edge gets.
Walls & structures
Vertical movement joints in concrete and masonry, including precast panel joints and brickwork articulation joints.
Re-sealing old joints: a large share of our joint work is cutting out failed sealant and re-doing it properly — correct backer rod, correct depth ratio, a sealant matched to the movement. If your joints have split, de-bonded or gone hard, send photos through the quote form.
Our process
How we seal an expansion or control joint
Whether it's a brand-new joint or a failed one being re-done, the sequence is the same — get the prep right and the sealant lasts.
- Inspect and measure. Check joint width, depth and movement type, and what runs over it — foot traffic, forklifts or vehicles — to pick the right sealant class.
- Prepare the joint. Cut out and remove old failed sealant on a re-seal, or clear formwork spacers and debris on a new joint, then grind and clean both joint faces.
- Prime where specified. Apply primer to the joint faces per the sealant manufacturer's data sheet, where the substrate calls for it.
- Install backer rod. Closed-cell backer rod sized slightly wider than the joint, set to the depth that gives the correct width-to-depth ratio (minimum 6 mm sealant depth).
- Gun and tool the sealant. Apply the specified sealant in full contact with both joint faces, then tool it to a smooth, consistent profile.
- Cure and clean up. Let the sealant cure per the data sheet before it takes traffic or load, and leave the site clean.
Matching sealant to joint
Which sealant suits which joint
The right sealant depends on what the joint has to survive — movement, weather or wheel loads. Use the sealant calculator to estimate quantity once you know the joint sizes, or the joint width calculator if you're still sizing the joint itself.
| Joint type | Typical sealant | Movement class | Why |
|---|---|---|---|
| Warehouse floor joints (forklift traffic) | Semi-rigid epoxy or polyurea | Low movement, high load | Hard wheels need a rigid, load-bearing filler — a soft flexible sealant shears and pumps out under repeated wheel loads. |
| External slab & pavement joints | Polyurethane (PU) | Around ±25% | Outdoor thermal movement plus UV and weather exposure — PU stays flexible and bonds well to concrete. |
| Wall & vertical movement joints | PU or hybrid polymer | ±25–50% | Needs a non-sag sealant that holds a tooled vertical profile while still moving with the structure. |
| Car park deck joints | Traffic-grade PU / deck sealant | ±25% plus vehicle load | Sees structural movement and vehicle wear, sometimes fuel or oil exposure — needs a tougher wearing system. |
| Precast panel joints | PU or hybrid polymer | ±25–50% | Panel joints move thermally and structurally; hybrid/PU systems handle that while staying weathertight. |
As a general guide, precast and expansion joint sealing in Melbourne typically runs $9–$15 per metre, general joint sealing $5–$12 per metre, with minimum call-outs of $250–$450 for small jobs — typical market ranges, not a quote. Full breakdown on the cost guide.
Know the warning signs
Signs your joints need re-sealing
- Split or torn sealant along the joint line.
- De-bonded edges — sealant has pulled away from one or both joint faces.
- Hard, brittle or chalky sealant that's lost its flexibility.
- Debris, dirt or standing water sitting in the joint.
- Chipped joint edges (arris) from forklift or vehicle wheels.
- Water staining on the slab underside or the wall below a joint.
None of that means the slab has failed — it means the joint has, and it's a sealant job, not a concrete job. Not sure if it's cosmetic or worth flagging? Our caulking inspections can tell you before you commit to a re-seal. Otherwise send photos through the quote form for a price.
Who this is for
Builders, facility managers and contractors we work with
Expansion and control joint sealing comes up across very different projects — new builds, existing facilities and civil works. We work on all of them, commercial, residential and industrial.
Builders
Joint sealing scheduled into the build program on commercial, industrial and residential projects — slabs, precast and structural movement joints.
Warehouse & logistics facility managers
Re-sealing worn floor joints on operating sites, scheduled around your traffic and shift patterns.
Strata & body corporate
External joint and pavement re-sealing across shared areas, car parks and building perimeters.
Civil contractors
Joint sealing on pavements, car parks and civil slabs as part of a wider project scope.
Where we work
Areas we service for expansion and control joint sealing
Gapless provides expansion and control joint sealing across Greater Melbourne and regional Victoria within about 90 minutes of the CBD. We travel to the job — commercial sites, apartment buildings, warehouses and homes alike.
Melbourne CBD & inner suburbs
Melbourne, Southbank, Docklands, Richmond, Collingwood, Fitzroy, Carlton, South Yarra, Port Melbourne, St Kilda.
West & north
Footscray, Sunshine, Werribee, Point Cook, Truganina, Laverton, Melton, Essendon, Broadmeadows, Epping, Craigieburn.
East & south-east
Box Hill, Doncaster, Ringwood, Glen Waverley, Clayton, Dandenong, Cranbourne, Frankston, Moorabbin, Cheltenham.
Bayside & Mornington Peninsula
Brighton, Sandringham, Mordialloc, Mornington, Mount Eliza, Rosebud, Dromana, Hastings.
Geelong & the west
Geelong, Lara, Corio, Torquay, Ocean Grove, Bacchus Marsh, Ballan.
Not on the list?
Ask. For commercial work we regularly travel further — send the suburb through the quote form and we'll confirm.
Joint sealing — frequently asked questions
What's the difference between an expansion joint and a control joint?
A control joint is a deliberate weak line that tells concrete where to crack as it shrinks; an expansion joint is a full-width gap that lets slabs or walls move without pushing against each other. Both need a flexible sealant that keeps water and debris out while allowing the movement to happen.
Why seal floor joints in a warehouse?
Unsealed floor joints collect debris, chip at the edges under forklift traffic, and let water through. A traffic-rated joint sealant protects the joint edges (arris) and gives a smooth, cleanable floor. The sealant must suit the traffic — soft sealants fail fast under hard wheels.
How much does joint sealing cost?
It depends on lineal metres, joint width and depth, whether old sealant must be cut out first, and the sealant class required. Send the details through the quote form for a free price.
Wondering what this costs? See typical Melbourne rates per metre on our caulking cost guide — or skip straight to an exact price with a free quote.
Free quote · no obligation
Get a joint sealing quote
Tell us the suburb and roughly what needs sealing — we'll come back with a price or a call to clarify. Quotes are free; we typically book with 1–2 weeks' notice.
- 10+ years' specialist experience
- Fully insured · SWMS & induction ready
- Pasco · APTC · Soudal · Bostik · Sika systems
Got photos or drawings? Send them on WhatsApp or call 0414 824 987.