Expansion Joint Foam for Concrete: Rolls, Strips and Backing Rod
Expansion joint foam is the filler that goes in the gap between concrete pours, or between concrete and a wall, post or footing. Our rolls and rigid strips are closed cell foam made in Australia, and the rolls have a pre-slit tear-off top strip that leaves a void for flexible sealant once the concrete is down.
Pick by the job: rolls for long runs and curves, rigid strips for straight joints that need a firmer filler, and open cell strips or round backing rod behind caulking.
Expansion joint foam at a glance
| Product | Foam | Size | Supplied as |
|---|---|---|---|
| Plain expansion joint foam roll | Closed cell cross-linked polyolefin, 28kg/m³, grey | 10mm thick, 100 or 150mm wide, 25m long | Per roll, or packs of 12 (100mm) or 8 (150mm) |
| Adhesive backed expansion joint foam roll | As plain, with a self-adhesive back | 10mm thick, 100 or 150mm wide, 25m long | Per roll, or packs of 12 (100mm) or 8 (150mm) |
| Rigid expansion joint foam strip | Closed cell cross-linked EVA, 90kg/m³, charcoal | 10mm thick, 2000mm long, 50, 75, 100, 150 or 200mm wide | Packs of 20; special order, about 3-10 days |
| Quick-Form foam strips | Open cell polyurethane, charcoal | 2000 x 20 x 30mm | Bundles of 100 |
| Round backing rod | Closed cell low density polyethylene | 10, 13, 15, 20 or 25mm diameter | 50m rolls |
Picking the right joint filler
Rolls for slabs, paths, driveways and curves.
Plain expansion joint foam roll and the adhesive backed roll are flexible and compressible, so they bend around columns, round bases and posts without cracking. The adhesive back holds the foam against formwork or an existing slab while you pour. Both are non-absorbent, UV resistant and made with fire retardant additives.
Rigid strips for straight joints.
The rigid expansion joint foam strip is EVA at 90kg/m³, much denser than the 28kg/m³ rolls, in 2m lengths and five widths from 50mm to 200mm. Use it where a stiffer filler suits the formwork. It is a special order item, so allow about 3 to 10 days.
Behind sealant and on site
Caulking backers. Quick-Form foam strips are open cell, so moisture and air reach the sealant from both sides and it cures evenly without bubbling. They compress more than closed cell foam, so one size covers a wide range of joint widths. For a round profile, use round backing rod: closed cell, compatible with all sealants, and it cuts the amount of sealant you need. Pump crews can also grab concrete pump clean-out sponges, and IXPE foam roll covers gap filling, seals and vibration dampening in 1000mm wide rolls.
Browse the full expansion joints and caulking strips category, or the wider building and construction range.
Other sizes and site supply
Other widths, thicknesses and grades are available on request; minimum quantities and extra lead time may apply. More construction uses are in The Best Foam Solutions for Building and Construction Projects.
Ordering for a job
For a job lot, call 1300 288 362 with your joint widths and lengths and we will work out quantities and freight with you.
Frequently asked questions
Ours is closed cell foam. The rolls are chemically cross-linked polyolefin at 28kg/m³ and the rigid strips are cross-linked EVA at 90kg/m³, both made in Australia. Closed cell foam is non-absorbent and resists most liquids and chemicals, and the rolls are made with fire retardant additives. For caulking backers we also supply open cell polyurethane strips and polyethylene round backing rod.
For most slabs, paths, driveways and pool surrounds, use a 10mm expansion joint foam roll in the width that matches your slab depth: 100mm or 150mm. Choose the adhesive backed roll if you want it to stay put against formwork during the pour. For straight runs that need a firmer filler, or widths of 50, 75 or 200mm, use the rigid strips.
Only the back. Both rolls are the same 10mm grey cross-linked polyolefin foam, 25m long, in 100mm or 150mm widths, with a pre-slit tear-off top strip. The adhesive backed roll has a self-adhesive back that sticks to formwork or an existing slab, which saves fixing it in place before you pour.
It makes the sealant void. The top 10mm of each roll is pre-slit, so once the concrete has set you pull that strip away and fill the gap with a flexible sealant. Because the strip is the same depth all the way along, the sealant depth stays consistent along the joint.
The rolls are 10mm thick, 25m long and 100mm or 150mm wide. The rigid strips are 10mm thick and 2000mm long, in 50, 75, 100, 150 and 200mm widths, sold 20 to a pack. Quick-Form strips are 2000 x 20 x 30mm in bundles of 100, and round backing rod comes in 10 to 25mm diameters on 50m rolls. Other sizes are available on request.
It is the same type of product. Closed cell expansion joint foam is known in the industry by several trade names, including Abelflex, FormFlex, Easy-Form, FoamJoint and Fast-Flex. Ours is made in Australia from cross-linked polyolefin or EVA foam and sold under our own product names, in the sizes listed on this page.
Use a compressible backer so the sealant sits at the right depth. Quick-Form open cell strips let the sealant cure evenly from both sides and suit a wide range of joint widths. Round backing rod is closed cell polyethylene in 10 to 25mm diameters, compatible with all sealants, and its round profile lets the sealant form the right shape for movement.