The Big Joint Filler Showdown
Take your ringside seat as epoxy, urethane, and polyurea face off for the title of “Best Joint Filler for the Job.”
- Polyurea, epoxy, and urethane caulk can be used as concrete joint fillers
- All three materials have advantages and disadvantages
- The location and budget for your project will determine which to use
- Your timeline for completion can also be an integral part of choosing the most appropriate filler
History is full of famous face-offs. First, there was the “Rumble in the Jungle.” Then, there was the “Thrilla in Manilla.” It was all leading up to the most exciting battle of them all: “The Jostle for the Joints.”
OK. It doesn’t have quite the same ring to it, but this showdown is required viewing for contractors and customers looking to create a winning concrete surface. Our contenders today are epoxy, urethane (sometimes called polyurethane), and polyurea caulk.
Joint fillers must be chosen well because joints face all the same beatings as the slab itself. Only by taking a closer look at each filler’s strengths and weaknesses can you make the best bet. We’ve booked you a ringside seat, so let’s ring the bell!
The shared strengths of our three contenders
All three are strong going in, each adhering well to concrete and creating a water-resistant seal. Epoxy and polyurea perform well in terms of lateral expansion and separation while retaining adhesion, with some experts giving polyurea the slight edge on that front.
All three contenders meet the required industry standards for toughness: a Shore A hardness of 80, to be precise. Now that the similarities are out of the way, it’s time to weigh up each filler separately.
The pros and cons of epoxy filler for joints
Originally out of Switzerland, this hard-wearing material has a long record of taking hits, dating all the way back to 1936. Epoxy can be formulated in one or two parts, the latter being a combination of hardeners and polymer resins. Joints filled with epoxy receive a stiff, plasticky finish that goes the distance against abrasion and compacting from foot traffic and heavy loads while adhering very strongly to the substrate.
Epoxy has a high level of resistance against chemicals, alkalis, oils, and liquids in general. It goes down easy but comes up fast since it’s simpler to remove than urethane, meaning less digging and elbow grease if it needs to be replaced. Epoxy comes in a wide variety of curing speeds and is tough against short-term temperature changes – a big bonus if the concrete is vulnerable to the freeze/thaw cycle.
Looking at the “loss” column, you’ll see that epoxy fillers rely on precise mix ratios to perform well. This isn’t really a material weakness; it’s more of a responsibility placed on the contractor applying it. You’ll need an expert to do it right.
Using epoxy filler for joints isn’t a good idea if your concrete is on the fancier side. It can lose color when up against UV light and ruin the aesthetic on more decorative floors. And finally, don’t try to use epoxy filler for joints when it’s already freezing because it won’t cure completely.
Polyurea vs. urethane caulk
Polyurea vs. urethane caulk is a whole other bout. Urethane has a high resistance to some acids, is less expensive than polyurea, and has a versatile curing time that can be set between minutes or hours by a skilled contractor. It’s also no pushover against UV radiation but can’t handle humidity above 70%. Applying urethane at that threshold can cause it to blister.
Polyurea is much better than urethane or epoxy when it comes to filling joints in cold conditions, performing well even in sub-zero temperatures. Polyurea fillers are much more versatile when it comes to coloring, meaning your joints can look as jazzy as you want them to! Epoxy can take color too, but it’s not working in the same weight class as polyurea on this one.
Another advantage of polyurea comes from one of its limitations, and once again depends on the skill of the contractor. Polyureas are applied using a meter-mix pump, which gives them a very brief “shelf life.” It must be applied quickly and precisely and will dry very quickly when it is.
It can handle humidity without breaking a sweat, but, like epoxy, it will start feeling the strain against UV radiation, which can reduce polyurea to a discolored, dull, or dusty condition.
So, which one is the winner for your site?
It all depends on what the average day on your site looks like. Are you dealing with chemicals that could end up spilling on the floor? Epoxy is probably the filler for you. Does the location experience regular shifts between hot and cold that could affect the surface? Epoxy again.
Then there’s the application environment. If your slab is outdoors, but the climate tends to be cooler and overcast, polyurea caulk could be the safest bet – but it isn’t a great choice for warmer, sunnier climes. Outside concrete is also up against varying degrees of sunlight day in and day out, which could make urethane the right choice. The same goes for indoor joint fillings, which nobody wants looking shabby from sun exposure.
Budget is always a deciding factor in any situation, and if funds are tight, you may have to skip fillers that require greater skill from the contractor. Large projects with tight schedules may not have the luxury of choice when it comes to expense – the faster curing fillers may be the only feasible solutions.
The surest way to pick a winner is to consult an experienced concrete contractor and tell them every detail about your site. Better yet, have them drop by for a personal inspection. Their expertise will make sure you get the real picture of how well each filler will perform for your specific surface.
Contact us and take the guesswork out of joint work
Our team of professionals can coach you on every aspect of concrete and do every job involved with the stuff except pouring it. We’ll quickly be able to call the winner in the polyurea vs. urethane caulk faceoff or tell you with confidence if epoxy is the champ. Just contact us to ask any questions or to outline your needs!