Crack injection kits

Crack injection kits DEFAULT

Sika Sikadur Crack Weld Injection Kit is a two component, low viscosity, fast curing epoxy sealing system for repairs to cracks in concrete and solid masonry. Conforms to ASTM C-881. For use in low pressure injection of cracks in structural concrete and solid masonry, as well as gravity feeding cracks in horizontal concrete and horizontal solid masonry.

Advantages: As strong as concrete. Convenient mix in the nozzle cartridge system. Cartridges fit standard caulking guns.

Capseal (x2) 300 ml
Injection Resin (x2) 250 ml
Capseal mixer nozzle (x2)
Capseal applicator fan (x2)
Cartridge Flow Restrictor (x1)
Injection resin mixers with extended tube (x2)
Push fit connector (x1)
Injection Ports (x16)
Pair of Gloves (x2)
Wooden Applicator (Tongue Depressor) (x2)
Instructional DVD (x1)

Requires applicator gun. See product datasheet for specifications.

NameSika Sikadur Crack Weld Injection Kit 432903
DescriptionSika Sikadur Crack Weld Injection Kit is a two component, low viscosity, fast curing epoxy sealing system for repairs to cracks in concrete and solid masonry. Conforms to ASTM C-881. For use in low pressure injection of cracks in structural concrete and solid masonry, as well as gravity feeding cracks in horizontal concrete and horizontal solid masonry.

Advantages: As strong as concrete. Convenient mix in the nozzle cartridge system. Cartridges fit standard caulking guns.

Capseal (x2) 300 ml
Injection Resin (x2) 250 ml
Capseal mixer nozzle (x2)
Capseal applicator fan (x2)
Cartridge Flow Restrictor (x1)
Injection resin mixers with extended tube (x2)
Push fit connector (x1)
Injection Ports (x16)
Pair of Gloves (x2)
Wooden Applicator (Tongue Depressor) (x2)
Instructional DVD (x1)

Requires applicator gun. See product datasheet for specifications.

5 Best Basement Wall Crack Repair Kit


Basement wall cracks are caused by various reasons, including mistakes in pouring or mixing concrete, shifting foundation, and leaks. Fortunately, basement wall cracking isn’t difficult to address because there are many repair kits available on the market.

The best way to repair cracks in concrete basement walls is by injecting them from the inside. Repair is often quick and inexpensive. The process only involves polyurethane or epoxy injected into the cracks.

We’ve listed the best basement wall crack repair kits below to help you make an informed buying decision. Check them out!


The 5 Best Basement Wall Crack Repair Kit


1. Emecole DIY Leaking Basement Wall Crack Repair Kit

DIY Leaking Basement Wall Crack Repair Kit (30 ft.) - Repair Poured Concrete Foundation Wall Cracks

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If you are looking for a kit that has everything you need, then this may be the one for you. The star of the show is the formula, which the company calls it the Emecole Metro 102 Premium Polyurethane.

The formula is specially designed for foundational walls. Hence, it is strong enough to be used for any concrete crack. Aside from that, it prevents water from entering when fully cured. In fact, you can even use it to seal swimming pool cracks.

The Emecole Metro 102 Premium Polyurethane expands 20 times its original volume. Thus, you can sure it will fill all the interior cracks. Once it’s cured, it can expand and contract together with the concrete. This unique attribute is especially desirable if the concrete is subjected to freezing and thawing cycles.

The kit includes enough formula to repair approximately 30 feet of crack. Also, it’s easy to handle because of its low viscosity. The package also includes a caulk gun, which is very important for the application of the formula.

Perhaps the only downside with this kit is the price. It’s a bit on the expensive side. However, you will still be getting your money’s worth knowing it works very well, and it is easy to use.


  • Very Thorough Kit – you probably don’t need anything else aside from what’s included in the kit.
  • Emecole Metro 102 Premium Polyurethane – a very well-engineered formula.
  • Experienced – the company has been around since 1987 and considered to be pioneers in the field.



2. RadonSeal Concrete Foundation Crack Repair Kit

RadonSeal Concrete Foundation Crack Repair Kit (10 ft) - The Homeowner's Solution to Fixing Basement Wall Cracks Like The Pros!

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This crack repair kit has a trick under its sleeve. For now, it’s good to know that with this kit, there’s no need to do drillings to repair a concrete crack. You only need the kit’s polyurethane formula that comes into two components.

There’s enough product to cover about 10 feet of crack. It’s worth pointing out that the formula is low-viscosity. This means it’s easier to manage and inject. And most importantly, it can easily penetrate voids, making it suitable for repairing hairline cracks. The product also bonds tenaciously to concrete, whether it is dry or wet.

However, it’s still flexible enough to allow the natural movements of the concrete. One of the best things about this kit is that the formula can block radon, a radioactive gas that’s classified as carcinogenic. Since it can block radon, it also naturally blocks soil, water, and vapors.

The price is also very affordable, which makes it an excellent choice if the budget is a bit tight. Since this kit is affordable, then you can’t really expect that it will include a caulk gun. Perhaps the only downside is that the formula can only cover 10 feet of crack.


  • Budget-friendly – it’s a very affordable crack repair kit
  • Low- pressure formula – there’s no need to use specialized equipment to inject the product.
  • Excellent barrier – blocks soil, water, vapor, and even radon


  • Can only repair 10 feet of cracks


3. Applied Technologies Concrete Foundation Crack Leak Repair Kit

20' Fast Set Concrete Foundation Crack Leak Repair Kit, Stop Leaks in Basement Walls

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While there’s nothing unique about this crack repair kit, it’s priced so well that it is hard to ignore. First of all, this kit is good at repairing concrete cracks. However, the formula is good enough for cracks in the foundation wall too. As a bonus, it also blocks the water in case the crack comes with a leaking. The formula can repair about 20 feet of cracks.

While it doesn’t provide the most amount of coverage, it also doesn’t offer the least. The name of the formula used in the kit is Hydra Stop 300. It is a non-shrinking urethane foam. You don’t want a formula that shrinks as that would open up leaks that may compromise the integrity of the wall.

Despite that, the foam is still flexible, and does not hinder the natural movements of the concrete. Another thing that’s worth mentioning is that the package includes a very detailed step-by-step guide. If you’re handy enough, you probably don’t need to hire anyone if you follow the comprehensive guide.

Also, the kit includes a caulking gun. It’s a convenient package, so you don’t have to go shopping for a gun, and worrying if it will fit with the product’s bottles. When talking about downsides, there are not a lot of glaring issues with the package. The kit is priced just right when considering what it includes. Perhaps if there’s a downside, then it is just a “jack of all trades, master of none” type of kit.


  • Good value – the price is just right, and it includes a caulking gun.
  • Non-shrinking formula – doesn’t compromise the integrity of the wall.
  • Easy-to-follow guide – it includes a detailed step-by-step guide.


  • Jack of all trades master of none


4. Mar Flex Concrete Crack Repair Kit

Mar-flex 6'-8' Concrete Crack Repair Kit (POLYURETHANE) For Poured Wall Construction

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This one is another budget-friendly entry to the list. It’s a crack repair system that’s designed for poured wall construction. Considering how affordable it is, it’s got most of everything you need to repair a concrete wall crack. The kit includes two jars of Crack and Seal Port Adhesive. Furthermore, the package has 15 surface ports. Assuming that you will be spacing the surface ports at 10 inches apart, you should be able to cover around 12 feet of crack.

The injected formula is made of polyurethane. It’s pretty much the standard for crack injection repair systems as it’s quick to dry. Also, it does not impede the natural expansion and contraction of the concrete.

Another thing that’s worth mentioning with this kit is that it comes with an instructional CD. It’s a quick “how-to” guide to help you with the process if you want to go with the DIY route. The guide is in English and Spanish.

Coming at a very affordable price point, it’s hard to point out glaring issues with this kit. Perhaps you could say that the surface ports only covering 12 feet of crack may be an issue.


  • Budget-friendly – one of the most affordable kits in this list.
  • Polyurethane – standard for crack injection repair due to its quick-dry and concrete-bonding attribute.
  • Instructional CD – available in English and Spanish.


  • Surface ports only cover about 12 feet


5. Flexomeric Concrete Foundation Crack Repair Kit

Concrete Foundation Crack Repair Kit - Low Viscosity Polyurethane - FLEXKIT-1050-10

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This kit is among the few that include a caulk gun. Well, it should be included because the formula that the package uses requires dual injections, which requires a tool that’s a bit specialized.

The kit is also designed to stop or prevent water leaks. However, it can be used for both dry and wet cracks. The formula is also excellent as it can expand 400% to 600% its original volume when fully cured. This is the reason why it does an excellent job at plugging water leaks.

Despite being air-tight, the formula remains flexible. It can adjust with the concrete shifting due to thermal cycles. Also, the kit is designed to repair cracks that are 1/16” to 5/16”. If there’s a downside to this kit, then it has to be the formula.
As mentioned above, you will need a dual cartridge gun. On the upside, there’s already a gun in the kit.


  • Stops water leaks – the formula is specially designed to stop or prevent leaking water.
  • Flexible – the formula remains flexible to accommodate concrete shifting.
  • Includes a caulk gun – no need to make a separate purchase.


  • The formula needs a dual injection gun.


Types of Basement Wall Cracks

Knowing the kind of cracks you have in your basement walls will help you determine the severity of damage that your home has sustained. However, you should keep in mind that any cracking you discover, especially in the foundation of your home, must be taken seriously. Inspect cracks closely and repair them to protect your home and ensure structural integrity.

Structural cracks are the most serious, so if you see them, you have to act as soon as possible as the cracks pose risks to your home’s structural integrity.

A sure sign of a deficiency is a crack that is ¼-inch wide or more. A structural crack in a basement wall is typically due to movement, whether it is from soil shrinkage, soil pressure or temperature changes.

If you spot moisture or water coming from structural cracks, the quicker you repair them, the better. Quickly changing patterns of local climates can cause cracks to worsen or lead to even more water and moisture issues.

A non-structural crack in basement walls doesn’t pose any threat to a home’s structure, and it usually results in leaking only when the snow melts or during rainstorms. Although there is no structural threat with this kind of basement wall crack, water that’s seeping into the basement is a matter that requires attention and has to be taken seriously.

Water leaking into a basement can ruin belongings, floors, walls, and contribute to the development of mold and mildew. When left unattended, non-structural basement wall cracks may get worse as well. This is why homeowners are advised to act fast in addressing cracks, no matter how small or insignificant they may seem. Don’t wait until water has seeped into your interior before you fix the issue.

Take note: Basement walls made of concrete often have minute cosmetic cracks which are normal from concrete’s natural curing process. With cracks that are between one to two millimeters each and run diagonally or vertically, they may be non-structural.

Horizontal cracks are the ones you need to watch out for because they signal serious damage to the structural integrity and foundation of a home.

While they’re seen in homes that have poured concrete foundations, they’re more commonly found in homes with brick or block foundations. Several things cause this kind of foundation damage, such as hydrostatic pressure that makes a basement wall to bow and soil pressure outside the foundation.

If you notice horizontal cracks, it’s important to repair the basement walls as quickly as possible before your home’s structural integrity is compromised. This kind of cracking can require extensive repair to secure the foundation and prevent it from causing any further damage.

Vertical cracks, in general, are the least severe and most common cracks you’re likely to encounter. They go all the way up or down or slightly diagonally, within 30-75 degrees vertical. They’re common occurrences in houses and usually result from foundation settling.

It is, therefore, not uncommon for a new house to have vertical cracks as the foundation of a home can settle greatly within the first year. Fortunately, vertical cracks are the least expensive and the easiest to seal. However, you should repair them immediately as they can grow or open even more.

Cracks that are diagonal run along basement walls at a 30 to 75-degree angle. A thin, hairline diagonal crack is usually wide at one end compared to the other. A diagonal basement wall crack is often caused by “differential settlement.” In this case, one side of the foundation of a home settles lower than the other parts.

This uneven tension causes the diagonal cracking and happens because they house has been built on uneven ground or slope. It may also because of the contraction or expansion of soil under a certain portion of a house.

This kind of cracking can be sealed but the reason for the differential settlement has to be addressed. The solution can be the installation of new gutters which redirects rainwater away from your property, especially from an area that gets flooded regularly and causes the soil under one portion of your home to shift.


Basement Wall Crack Repair Methods

As you may already know, there are two different methods for repairing basement wall cracks: polyurethane foam and epoxy injection. Read on to know the difference between the two.

Polyurethane Foam Injection

Urethanes react with water and moisture in basement wall cracks to foam and then expand inside the walls. Polyurethane foam injection fills the void all the way, top to bottom.

As a matter of fact, urethanes expand as much as 30 times their initial volume. The foams are flexible, plus they move with contraction and expansion in basement walls from thaw/freeze cycles.

Additionally, less resin is required with urethane foams as they can expand in volume. This makes them a more economical choice than epoxies. Lastly, urethane injection is easier to do compared to epoxy injection.


  • Easier to use
  • Less expensive
  • Flexible
  • Fills wider cracks


  • Not for structural repair


Epoxy Injection

Epoxies weld basement wall cracks together and they can restore structural strength. The strength of the bond is a lot higher than concrete, and movement is eliminated within a concrete basement wall during contraction and expansion cycles.

Home foundations that have a continuous stress load in them or are constantly moving may require additional repair methods to stabilize basement walls and prevent further damage. Epoxy is a lot stronger compared to concrete, but continuous stress load can cause walls to crack again.


  • Stronger than concrete
  • Offers structural repair
  • High strength weld


  • More expensive compared to urethanes
  • Concrete can re-crack if walls are still moving
  • Bond strength is less when done in wet basement wall cracks


How to Fix a Leaking Crack in Basement Wall?

While concrete port walls are reasonably strong and durable, there are instances that cracks can arise.

Cracks can happen, whether the wall is textured or non-textured. Also, the wall can be classified into structural, non-structural, dry, or wet and leaking. No matter the classification, the process of repairing the crack is the same whether you are using epoxy or urethane foam.

Repairing a crack is a multi-step procedure. Each step must be done correctly to ensure the structured of the wall won’t be compromised any further.

Basic Overview

Before we cover the steps, it’s best that you know the fundamental idea behind this repair guide.

A visible crack in the wall is just the tip of the iceberg. Inside the crack could be a network of more cracks. In other words, you can’t just cover the crack with a seal of some sort. You need to fill up the void created by the crack to plug possible leaks and minimize structural compromise.

The most common products to fill-up the crack are epoxy and urethane foam. However, you can’t just inject these products mindlessly. You’d want the product to go inside the crack. Hence, you first need to seal the crack, so the product has nowhere to go but inside.

And yet, you can’t seal the crack completely because there’s no way for you to inject the product. That’s why you need to install surface ports.

The surface ports become an entry point for the product. Since you will be starting at the bottom port, the product will fill the crack while going up. Eventually, it will flow out from the next porthole above. That’s your signal to stop injecting on the current porthole, seal it and move to the next upper porthole.

By repeating this step, you’ll eventually fill up the crack with your chosen product. Now that you know the basic idea, you can move to the finer details in the step-by-step guide below.

  • Step 1: Preparing the Crack

The first step is to clean the crack thoroughly. You’d want to clean about two inches of both sides of the crack. Also, you’d want the concrete wall to be exposed, and that means removing plaster, paint, or any coating.

Once you scrape and clean the areas around the crack, make sure to dust it off with a soft brush or a vacuum.

  • Step 2: Marking Surface Ports

Repairing a crack requires the installation of surface ports. These ports are the entry points for your epoxy or urethane foam that will be injected later on in the process. This also means that you need to mark the spot where you want to place the surface ports.

As a rule of thumb, the distance between two ports should be the same as the wall’s thickness. This could be from 6 to 10 inches.

You’d want to start marking at the start of the crack that’s closest to the floor. Continue going up while marking the surface port locations.

Important: The area around the crack must be completely dry. If it is wet or damp, you must first dry it before moving to the next step. You can use a heat gun or compressed air to dry the wall thoroughly.

  • Step 3: Injection Port Placement

The surface ports come with two parts – the surface port itself and the port cap. Remove the cap if it is attached to the surface port. Also, make sure you don’t lose the cap as it is essential for the upcoming steps.

The next step is to prepare your adhesive. After that, place the adhesive to the port. Bond the surface port to the previously marked locations.

Important: Do not allow the adhesive to block the surface port or the crack underneath it. Otherwise, the epoxy or urethane foam won’t reach the insides of the crack.

  • Step 4: Sealing the Crack Surface

The next step is to place a surface seal over the crack and base of the surface port. You’d want the seal to be around one-eighth of an inch thick and spread about two inches from both sides of the crack.

However, place more adhesive around the surface port to ensure a good seal. If the crack goes through the opposite side of the wall, then you need to place the surface seal on that side. If you don’t do this, the epoxy or urethane foam will flow out on the other side instead of going up the crack.

Allow the surface seal to cure, about fingernail hard.

Here’s a tip that will make the task easier. Lightly stick the surface caps near the surface ports as the surface seal is drying. By doing so, you can simply pull out the surface caps when the time comes that you’ll need it. However, you want to place it lightly, or you will be having a hard time pulling it out.

Important: To ensure that there’s no leakage or blockage, squeeze a bottle of water into the top-most surface port. The water should trickle out from the surface ports below. Also, you don’t want the water to escape anywhere else aside from the surface port.

  • Step 5: Injecting the Crack

The next step is filling up the crack with epoxy or urethane foam via the portholes. Hence, start loading the product into a dispensing gun with a static mixer attached. You’d also want to dispense a small amount if it’s a newly loaded product to purge out the air. Start from the bottom porthole and work your way up.

The key for best results in applying is slow, consistent, and low injection pressure. That’s why it is highly recommended that you use a spring-loaded dispensing gun. With a spring-loaded dispensing gun, a spring is compressed when you pull the trigger. As the spring decompresses, it injects the product into the porthole. Because it’s the spring that applies the pressure, a consistent product injection is achieved.

Continue injecting until you see the product coming out on the next porthole above. As you move to the next porthole, don’t forget to plug in the cap. Repeat this process until you are finished injecting the top-most porthole.

After that, let it cure. Drying times can widely vary. But generally, urethane foam will take two hours. For the epoxy, it’s typically 24 hours.

  • Step 6: Remove the Surface Seal and Injection Ports

When the curing time has elapsed, the next step is taking off the surface seal and the portholes. You can use a putty knife to take out the surface seal. If the portholes are too stuck for a putty knife, you can knock it off using a hammer.

At this point, you’re mostly done with the crack repair. The next step is up to you. You can do a bit of sanding and dusting off. Or, you can do it thoroughly to prepare the wall for coatings like paint or plaster.



With our buying guide on the best basement wall crack repair kits, you are now able to make an informed buying decision!

Before you make a purchase, here are some guidelines to keep in mind: if a crack has to be repaired structurally and the area has to be stronger than the material around it, you need to opt for epoxy injection.

If basement wall cracks have to be repaired just to prevent leakage of water or cracks are actively leaking, polyurethane injection is often the best choice.

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10’ Crack
Injection Kit

Single-Use Crack Repair kit includes the materials and accessories for low-pressure injection and repair of approximately 8-10 lineal feet. The only tool you’ll need is a standard caulking gun.

  • Single Use Kit Crack Injection

Product Overview

Knowing that poured concrete walls are especially prone to shrinkage cracks resulting from the curing process, a contractor has to be prepared to offer a solution to a homeowner. Our single-use, polyurethane crack repair kit is cost effective, easy to install and provides a permanent fix to poured wall cracks and seals out unwanted water seepage. This type of repair is recommended for cracks that pose no structural risk to the foundation and it require not outside digging.

Key Features

  • Repairs up to 10 lineal ft.
  • Easy to follow video included
  • Only tool needed is standard caulking gun
  • Polyurethane

Product ID

Included in 10’ Crack Injection Kit

  • (1) 8 oz. jar Mar-flex Port Paste A
  • (1) 8 oz. jar Mar-flex Port Paste B
  • (2) Wooden Sticks
  • (12) Surface Ports and Caps
  • (2 Cartridges) Mar-flex Injection Polyurethane/Epoxy Resin 1:1
  • (2) 3/8”: 24 Mixing Nozzles
  • (1) Injection Hose Assembly with plastic shut-off valve
  • (2 pair) Latex Gloves
  • (1) Wire Brush
  • (1) Drop Cloth
  • (1) Complete Instructional DVD

Training Materials & Videos

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Fast-Set Polyurethane Concrete Crack Injection In a Basement Wall

Do-It-Yourself Foundation Concrete Crack Repair Kits

PipeTite Gap Filler Kit - the Permanent Solution for Sealing Concrete Penetrations

The size of the holes drilled through foundation walls is always a size larger than the pipes and workers just stuff some mortar into the void. Over time, the mortar will inevitably deteriorate and start leaking water. These recurrent water leaks are an endless nuisance to many a homeowner. Hydraulic cement does not stick to pipes and caulk will get loose.

The PipeTite Gap Filler Kit provides a permanent solution for pipe penetrations through poured concrete walls. It is very similar to the D-I-Y Foundation Crack Repair Kit but smaller. The polyurethane foam tenaciously adheres to concrete, plastic, and metals. It beats caulking, mortar, hydraulic cement, or patching compounds. It will never separate, peel, or leak – it is permanent!

The expanding polyurethane will fill the entire gap around the pipe and water will never get in again. It also protects the concrete by preventing water from getting inside the gap. All you need is a common caulking gun.

Application is very similar to crack injection:

First, glue on one or more injection ports around the pipe and enclose the gap with the surface sealer. Let cure and inject the polyurethane polymer, which forcefully expands and fills the entire void with polyurethane foam. In case there already is solid mortar, you can drill holes through it with a masonry bit and inject the polyurethane sealant through it.

Form wire ties: These steel wires or rods hold the forms together when foundation walls are poured. But once the exterior waterproofing breaks down, water attacks the form ties, making them rust or fall out. Water starts squirting into the basement. Caulking or patching are only temporary fixes. Glue an injection port right on top of the hole and inject the PipeTite expandable urethane to fill the void and stop the leak permanently.

concrete hole repair

Kits crack injection

Concrete Contractors:Find Epoxy and Polyurethane Products and Suppliers

While concrete cracks appear to be typical, it is not recommended that they remain ignored. Most homeowners best identify concrete cracks in their basement, either on the foundation wall or on the floor. They may also recognize cracks on the garage floor, patio or in-ground pool.

These cracks typically due to drying shrinkage, thermal movement or other causes usually are minor and result in few problems. More often than not, a foundation crack will widen over time and result in water seepage or possibly the loss of structural integrity. Foundation and slab cracks are not only an eyesore, but they may hinder the value of the home.

Fortunately, there is an easy way to permanently repair such cracks without the need for costly and disruptive excavation or drain tile. Poured foundation cracks may be repaired by using low-pressure injection of an epoxy or polyurethane foam material. For the repair of concrete floor cracks, certain epoxies and polyurea materials exists, suitable for such slab repairs.

The application of such materials may be completed by a basement waterproofing contractor or a do-it-yourself homeowner. Either way, the repair of concrete cracks in either the foundation or the slab may efficiently and effectively be completed in as little as an hour or more.


Most basements eventually leak. "Even if a crack is not leaking now, eventually water will find it," says Lou Cole, president of Emecole Inc., Romeoville, Ill., a manufacturer of epoxies and polyurethane foams for all types of foundation crack repair. Cole says that in the Midwest, crack injection has been an accepted way of tackling these repairs for many years, and more and more foundation repair contractors around the country are adopting the technique because it is cost-effective, reliable, and permanent.

"Emecole's customers, primarily residential waterproofing contractors, have less than a 1% callback rate for crack repair work. More than 99% of the time, crack injection will fix the problem," says Cole. "Most contractors in the Chicago area (as well as other parts of the country) warranty the injection repair for the life of the structure," he adds.

Cole launched his company in 1987, after coming up with the concept of dual-cartridge dispensing of two-component materials using a spring-assisted dispensing tool similar to a caulking gun. The application that seemed to show the most promise for his dual-cartridge system was low-pressure injection of cracks in concrete. That gave him the impetus to develop a line of epoxies and polyurethane foams specifically formulated for those types of repairs.

The whole purpose is to fill the crack, from front to back, with epoxy or polyurethane. "For basement walls, low-pressure injection is the best way to ensure that the crack is completely filled," Cole maintains. This method is effective for filling cracks 0.002 to 1 inch wide in walls up to 12 inches thick. It can also be used to fill cracks in concrete floors and ceilings.


So which material is better for repairing concrete cracks: epoxy or polyurethane foam? The answer isn't always clear-cut. In many cases, either material can accomplish the task, and applicators may simply choose the material they have the most experience with. But here are some general guidelines: If the crack needs to be structurally repaired and the area needs to be as strong or stronger than the concrete around it, use an epoxy. If the crack needs to be repaired only to prevent water leakage or the crack is actively leaking, a polyurethane is usually the best choice. Here's a look at the advantages and limitations of each material.


Epoxies for crack injection are available in a range of viscosities, from ultra-thin to paste-like, to accommodate cracks of different widths. Coles advice is to use whatever viscosity is needed to inject a given crack at pressures less than 40 psi. The wider the crack, the thicker the material required.

The main advantage of epoxies is their amazing compressive strength, which at 12,000 psi or greater exceeds that of most concrete. That's why epoxies are the only choice for cracks requiring structural repair. However, epoxies cure very slowly, generally taking hours to harden. This can be an advantage because it allows time for the epoxy to flow into even the smallest crevices. On the other hand, its also possible for the epoxy to flow out of the backside of the crack before it has hardened if the backfill outside the wall has separated from the foundation.

"Often there are voids behind cracks due to soil erosion or poor compaction," explains Cole. That's why the crack is leaking in the first place; its easy for water to enter.


If there is concern about material leaking out the back of a crack, polyurethane foams should be used. These elastomeric, fast-setting foams are effective alternatives for applications involving only crack sealing (waterproofing) and not structural repair. Because of their elastomeric nature, they are able to accommodate slight concrete movement so the seal stays intact. They also begin to harden and foam within minutes of injection. This reduces the chances of the material flowing out of an injected crack while still in liquid form, and even if some does leak out, the foam will fill the void.

"Urethanes are great for basic crack filling. They add practically zero compressive strength, but in most residential applications, you don't need it," says Cole.

Concrete Contractors:Find Epoxy and Polyurethane Products and Suppliers


Using low-pressure crack injection, foundation and basement crack repair kits seal basement cracks from the inside, eliminating the need to excavate the soil from around the outside of the foundation. The kits are available with all the tools and materials needed to treat cracks ranging from 10 to 60 feet in length and include step-by-step written instructions as well as a video tutorial.

You can choose from crack repair kits that use either an injectable polyurethane foam or an epoxy, depending on the type of cracks you have. Polyurethane crack injection kits are recommended for non-structural leaking cracks resulting from concrete shrinkage or minor settlement while epoxy injection kits are designed to treat more severe cracks that compromise the structural integrity of the wall.

Here's how to decide which foundation crack repair kit to use:

  • Determine the total length of the crack(s) needing repair and select the appropriate kit size (10, 30, or 60 feet).
  • Determine whether you need to repair the crack with epoxy or polyurethane foam. Use a polyurethane foam kit for repairing leaking non-structural cracks and an epoxy kit for repairing structural foundation cracks wider than a quarter of an inch or large areas of multiple cracks.


Here are the basic steps for successful low-pressure crack injection. Keep in mind, however, that the type of epoxy or polyurethane used and the time required for injection will vary with each job depending on the crack width, wall thickness, and other conditions. These can also be bought as as crack repair kits that some with all the tools and supplies needed for the project.

Install injection ports: Surface Ports (short rigid-plastic tubes with a flat base) serve as handy entryways for getting the repair material into the crack. They eliminate the need to drill into the concrete, reducing labor time and cleanup. The base of the port is placed directly over the crack and bonded to the surface with an epoxy paste. A general rule-of-thumb is to space the ports an inch apart for each inch of wall thickness.

Seal the surface: Use an epoxy adhesive to seal over the surface ports and exposed cracks. The paste cures in about 20 to 45 minutes to provide a surface seal with excellent bond characteristics that holds up under injection pressures. The entire exposed crack is covered with the paste, leaving only the port holes uncovered.

Inject the crack: Begin injecting at the lowest port on the wall and continue until the epoxy or urethane begins to ooze out of the port above it. That's the visual sign that the crack has been filled to that level. Plug the first port with the cap provided and move up to the next port, repeating this procedure until the entire crack has been filled with epoxy or urethane. Let the compression spring on the dispensing tool push the material into the crack using slow, constant pressure. This will reduce the possibility of leaks or blow-outs and allow time for the repair material to fully penetrate the crack.

Remove the ports: Allow 24 to 48 hours at room temperature for the epoxy or polyurethane to cure and penetrate into the cracks. The injection ports can then be removed by striking them with a trowel or hammer. If appearance is an issue, the epoxy surface seal can be chipped away or ground off with a sanding disk. Another option is to use a surface seal that can simply be peeled off the wall after the repair is fully cured.

DIY Crack Repair Kits for homeowners


The secret to effective crack injection, whether using epoxies or polyurethane foams, is gradual introduction of the liquid polymer into the crack at low pressures (20 to 40 psi). This method requires some patience, but it allows the applicator to monitor the injection process and ensure that the crack is completely filled. Incomplete injection of a crack is the most common reason for crack repair failure.

To fill a typical crack in a residential foundation wall, injecting at pressures above 40 psi may not be effective. At higher pressures, the liquid has enough force to overcome gravity and rise up the crack without filling the backside, which is typically narrower than the front of the crack. High-pressure injection is better suited for repairing cracks in very thick-walled structures or where a high volume of water flow must be stopped (such as dam repairs).

Concrete Repair and Troubleshooting


Dual-cartridge dispensing, using disposable or reusable cartridges or containers, is a cost-effective completely portable method of injecting two-component polymers. The equipment also requires minimal maintenance and virtually no cleanup. At the end of the day, you simply discard the spent cartridges or reseal a partially used cartridge for reuse on another job. Each cartridge contains 16 to 22 ounces of material.

Automated proportioning equipment that dispenses bulk quantities of material also is available and may be the best choice on jobs requiring higher injection pressures or large volumes of material. But this equipment is expensive and cumbersome, and typically overkill for smaller residential jobs requiring only a few gallons of epoxy.

A spring-assisted dispensing tool allows complete control of injection pressures to keep them between 20 to 40 psithe best range for complete crack filling. The user simply changes the spring tension to adjust the force generated. Manual tools using a drive rod rather than a spring are difficult to control and may result in injecting at pressures much higher than desired. Air-powered tools are also available for dual-cartridge dispensing and allow control of injection pressure.

Because the epoxies and polyurethane foams used for crack injection are two-component materials, it is critical to mix them at the correct ratios to avoid problems with unreacted polymers. The dual-cartridge dispenser also acts as a proportioning device by using a static mixer, available in various sizes, to accurately mix the two components.

"The cartridges and static mixer eliminate a lot of problems," says Cole. "You don't have to be a chemist onsite. You just put the static mixer on the dispensing tool to achieve the right ratio and to properly mix the two components."


Low-pressure injection is ideal for fixing cracks in most poured-in-place residential basements. But in some cases you may need to pursue other remedial measures, along with crack sealing, to guarantee a complete fix.

If the foundation has settled due to compressible or improperly compacted soil, poor drainage, or uneven moisture conditions, use of hydraulically driven piles or piers may be required to lift the foundation and prevent future settlement. However, piering won't seal existing cracks, which may still need to be injected to prevent leaks after the foundation has been stabilized.

Similarly, crack injection can work hand in hand with carbon fiber reinforcement to stabilize and reinforce poured foundation basement walls that have bowed and cracked. "We often recommend the use of carbon fiber stitching in conjunction with crack injection repairs," says Cole. "It's better than stitching the crack with rebar and improves the chances that the crack will not reopen if there's ongoing, unforeseeable movement of the wall."

Cole says that crack injection is not a solution for fixing cracks in masonry block foundation walls. It also can't be used if water is leaking from a crack between the seam of the wall and the slab, which indicates a water table problem.

Allowable crack widths

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