Selection reference
Choose a joint filler by floor and service condition
A joint filler is not a joint sealant. It is there to fill the joint full depth and support the joint edges against hard-wheeled traffic, so the decision runs on floor traffic class, service temperature, appearance and how quickly the floor must reopen. Confirm the product against the project specification and the current Metzger/McGuire data sheet.
| Floor or joint condition | What to confirm | Examples in this category |
|---|---|---|
| Heavy industrial floors, hard-wheeled traffic | Contraction and construction joints in floors carrying forklifts and heavy material handling loads. Confirm service temperature stays between 40°F and 120°F, the joint can be filled full depth, and whether dispensing is manual or by pump: MM-80 mixes 5:1 for manual work, MM-80P mixes 1:1 for dual-component pumps. | MM-80 1 gallon, MM-80P 10 gallon |
| Industrial and retail floors needing a fast reopen | Rapid-set polyurea for the same joints where the floor cannot be closed for an epoxy cure, or where a polished or exposed slab makes staining and color a concern. Confirm the service temperature range and the color, and note that RS 88 is not recommended under VCT or other non-breathing floor coverings. | Spal-Pro RS 88 600ml, RS 88 10 gallon |
| Freezer, cooler and cold-temperature work | Placements below the epoxy range. RSF and Spal-Pro 2000 are published for application at temperatures as low as -30°F, with Spal-Pro 2000 returning to service in 30 minutes or less. Confirm the box temperature at the time of placement, not the design temperature. | Spal-Pro RSF 1500ml, Spal-Pro 2000 450ml |
| Retail and moderate-duty warehouse floors | Edge-Pro 80 cures to a softer Shore A 80-81 and is published for exposed retail floors and moderate-duty warehouse floors down to -20°F; Edge-Pro 90 cures harder at Shore A 90-92. Match the hardness to the traffic rather than to the price, and check the color against the finished slab. | Edge-Pro 80 600ml, Edge-Pro 80 10 gallon, Edge-Pro 90 600ml |
| Spalled joint edges and surface defects | Where the edge is already broken down, the repair is a rebuild, not a refill. Armor-Hard is a structural epoxy system supplied as a kit with aggregate for rebuilding spalled edges and surface defects in heavily trafficked floors. Confirm the depth and area of the repair and the return-to-service window. | Armor-Hard Kit |
| Slab panels that rock or deflect under load | Deflection under material handling traffic usually points to slab curl or a subgrade deficiency, not to the joint filler. Stabilizer EXP is a two-component high-density polyurethane foam injected into the void beneath the panel, with an installation and service range of 38°F to 100°F. Diagnose the cause before filling the joint again. | Spal-Pro Stabilizer EXP 1500ml |
Also stocked: Spal-Pro SPF stain-preventing film in 1 and 5 gallon, applied to the joint shoulders so overfill does not stain the slab, and RS 88 pigment packs in Dovetail Gray, Gauntlet Gray, High Tea, Brevity Brown, Burnt Sienna and Black. Cartridge fillers need a matching dual-component applicator; see caulking guns and applicators.
Field planning
Plan the joint filling work
Most filler failures come from installation: the joint was filled too early, filled too shallow, or filled without proper preparation. Use the manufacturer installation instructions together with the floor schedule.
Fill full depth, and prepare the joint
Metzger/McGuire publishes full-depth installation in saw-cut control joints, or a 2 in minimum where the joint depth exceeds 2 in, and 2 in deep in formed construction joints that are not saw-cut, consistent with ACI and PCA guidance. A partial fill leaves the joint edge unsupported, which is the condition the filler exists to prevent.
Joints must be clean, dry and sound before filling. Where a shrinkage crack below the joint is wide enough to swallow material, it can be choked off with clean dry silica sand before the filler goes in.
Time the fill against shrinkage
Concrete keeps shrinking after the floor is placed, and joints keep opening. Filling as late as the construction schedule allows reduces the amount of separation that shows up later. Specifications often set a minimum age before filling for this reason.
If joints do open after installation, Metzger/McGuire's guidance is to refill voids wider than about a credit card with additional filler or with Spal-Pro RS 88, and its Technical Bulletin T11 covers the causes and corrections for joint filler separation.
Traffic return and temperature
Return to service drives most product choices here. MM-80 is published as light-traffic ready in 6 to 8 hours and full traffic in 8 to 12 hours at 70°F, with a 15 to 30 minute pot life. The rapid-set polyureas reopen far faster, which is why they dominate occupied retail and tight construction sequences.
Service temperature narrows the field before anything else does. The epoxies are published for 40°F to 120°F, RS 88 for 32°F to 120°F, Edge-Pro 80 down to -20°F, and RSF and Spal-Pro 2000 down to -30°F for freezer and cooler work.
Color, staining and finishing
Fillers are installed slightly overfilled with a crowned profile and then razored flush once cured. On polyurea the crown can be shaved within about 15 minutes of placement depending on temperature; epoxy is shaved after its initial cure.
Overfill that is not removed can leave a light stain on porous slabs, which fades with traffic and cleaning. Spal-Pro SPF is applied to the joint shoulders first to avoid it. On polished, stained or exposed floors, confirm the color choice against a sample of the finished slab, not against a chip.
Before you order
Specifications, quantity and submittals
Use the floor specification and the current manufacturer data to confirm the product, the quantity and the documents the job needs.
Match what the spec calls for
There are no ASTM or government standards for floor joint fillers. Metzger/McGuire states that MM-80 meets or exceeds the joint filler guidelines in ACI 302.1R, ACI 360 and the PCA floor guidance, and many floor specs are written around those documents. Check whether the spec names a filler class, a Shore hardness or a specific product before substituting.
Calculate linear footage and yield
Measure the total joint length, then work out the fill volume from the joint width and the fill depth, not from the floor area. Add the random cracks and any edge rebuild separately. Cartridges suit repair and small runs; 10 gallon units suit full floors placed through a pump.
Confirm color and accessories
Color is ordered per product, and pigment packs are separate items on some units. Put the color on the purchase order alongside the product, and add the applicator, mixing tips, SPF and any blades or clean-out tooling at the same time so work is not waiting on a consumable.
Project orders
Request Metzger McGuire project pricing
Send the product, color and footage for your floor. If the filler is still under review, include the floor type, the traffic, the service temperature and the joint detail and we can cross-reference it against the Metzger/McGuire range.
Include with your request
- Product, color and packaging
- Linear footage, joint width and fill depth
- Floor type, traffic and service temperature
- Delivery ZIP and required-on-site date
Joint filler questions
What is a semi-rigid joint filler, and how is it different from a sealant?
A sealant is soft and elastic and exists to keep water and debris out of a moving joint. A semi-rigid filler is hard but slightly resilient, and it exists to fill an interior floor joint full depth and support the joint edges so hard wheels do not break them down. Metzger/McGuire pioneered the category with MM-80 and describes it as the filler ACI and PCA joint filler guidance is based on.
Epoxy or polyurea: which joint filler should I use?
Both are 100% solids, two-component, semi-rigid fillers, and both protect joint edges. Epoxy, MM-80 and MM-80P, is the long-standing industrial standard and is published for service from 40°F to 120°F. Polyurea, Spal-Pro RS 88 and the Edge-Pro line, sets far faster, handles colder placement and is generally the choice for occupied retail, polished floors and tight schedules. Freezer and cooler work goes to the polyureas published to -30°F.
What is the difference between MM-80 and MM-80P?
The formulation family is the same; the mix ratio is not. MM-80 uses the original 5:1 ratio and is intended mainly for manual dispensing. MM-80P uses a 1:1 ratio for dual-component mechanized pumps, the usual method for filling full floors. Both cure to a gray semi-rigid filler at Shore A90-95.
Spal-Pro RS 88 or Edge-Pro 80?
Duty and hardness differ. RS 88 is the heavy-duty polyurea for industrial, retail and commercial floors carrying hard-wheeled traffic. Edge-Pro 80 cures softer at Shore A 80-81 and is published for exposed retail floors and moderate-duty warehouse floors, with a lower temperature range down to -20°F. Edge-Pro 90 sits between them at Shore A 90-92. Match the hardness to the traffic the floor will actually see.
How deep should the joint filler go?
Full depth in saw-cut control joints, or a 2 in minimum where the joint is deeper than 2 in, and 2 in deep in formed construction joints that are not saw-cut, per Metzger/McGuire's published instructions and the ACI and PCA guidance behind them. Backer rod belongs in a sealant joint, not under a floor joint filler; using it here leaves the edge unsupported.
Why did my joints separate after they were filled?
In most cases the slab kept shrinking and the joint kept opening after the fill. It is a concrete movement issue rather than a product failure. Metzger/McGuire's guidance is to refill voids wider than about a credit card with additional filler or with Spal-Pro RS 88, and its Technical Bulletin T11 covers the causes and corrections in detail. Filling as late in the schedule as possible reduces how much shows up.
Can joint filler be installed in a freezer or cooler?
Yes, with the right product. Spal-Pro RSF and Spal-Pro 2000 are published for application at temperatures as low as -30°F, and Spal-Pro 2000 returns to service in 30 minutes or less. The epoxies are not suited to it; their published range starts at 40°F. Confirm the actual box temperature at the time of placement.
Can the filler be color matched to a polished or stained floor?
Yes. Metzger/McGuire pioneered color-matched industrial joint fillers and offers a wide standard color range with custom matching available, which is why the cartridges on this page are listed by color name rather than as a single gray. Pigment packs are also stocked for RS 88. For a stained or polished floor, match against a sample of the finished slab and order the color with the filler.
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