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TEK 19-06A

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Successfully sealing joints, such as control joints and around door jambs and window frames, in concrete masonry walls depends on the overall design and construction of the entire building envelope. Movement joints (also called control joints) are needed in some concrete masonry walls to accommodate drying shrinkage, thermal movements, and movements between different building components. Movement joints, joints around fenestration, doors and penetrations, and isolation joints (joints at dissimilar material interfaces) rely on joint sealants to help preserve the overall weather-tightness of the building envelope. In addition, properly sealed joints may be required to meet a specified fire resistance rating or sound transmission class.

The sealant’s primary role is to deform as the joint moves, maintaining the seal across the joint. Most joint sealants are field-applied (as opposed to preformed). For instance, a raked-out mortar joint or open movement joint may receive sealant from a gun-squeezed cartridge, typically applied over a backup material.

This TEK provides a basic overview of joint sealants, installation guidelines to help ensure longevity, and recommended maintenance procedures, based primarily on ASTM C1193, Standard Guide for Use of Joint Sealants (ref. 1) and ASTM C1472, Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width (ref. 2). This TEK does not address adhesives.

For optimum performance, the sealant must be properly applied to a well-constructed joint. For example, joints that are too thick relative to the width may cause failure of even the best sealant. Detailed information on control joint design and construction is available in TEKs 10-1A and 10-2C (refs. 3, 4).

Control joints in concrete masonry construction are classified as butt-joints, where the sealant is exposed to cyclicaltension and compression as the joint expands and contracts. Therefore, control joint sealants should be able to maintain their original shape and properties under these conditions. In addition, joint sealants should be impermeable, deformable to accommodate the joint movement, and be able to adhere to concrete and masonry materials or be used with an appropriate primer. The use of primers has been reported to improve bond as well as watertightness at the joint. Because many factors influence a wall’s water penetration resistance, the reader is referred to TEK 19-2B, Design for Dry Single-Wythe Concrete Masonry Walls (ref. 5) for more complete information.

(Video) A Guide for Placing Control Joints in CMU Tutorial

Some variables to consider when selecting a joint sealant are the sealant’s: joint movement capability (typically reported as two percentages, one for elongation and another for compression), time to set-up/cure, adhesion/bond strength to concrete masonry or other substrates, hardness, tensile strength, durability, expected life in service, ease of installation, primer requirements, application temperature range, paintability, warranty requirements, and sag-resistance. Materials that dry out rapidly and/or do not effectively bond to masonry, such as most oil-based caulks, are generally not recommended for use as concrete masonry joint sealants.

In-service conditions for the particular application must also be considered. For example, for joints that are not exposed to the weather, aesthetic factors such as available colors may be more important than the weather-resistance of the joint. Other applications may require properties such as chemical or fire resistance.

In short, no single sealant will meet the requirements of every application. The following sections briefly describe the most common materials used for concrete masonry joints.

Masonry Joint Sealants

Sealants must comply with ASTM C920-11 Standard Specification for Elastomeric Joint Sealants (ref. 6). Sealants used for concrete masonry joints and at penetrations in concrete masonry walls may be polyurethanes, polysulfides, acrylics, silicones, or even modified blends of each. Thesesealant materials tend to have:

  • high resistance to aging and weathering,
  • good resistance to low-temperature hardening,
  • moderate resistance to age-related hardening,
  • high resistance to indentation,
  • low shrinkage after installation, and
  • nonstaining properties.

Backup Materials

Backup materials are used to: restrict the sealant depth, support the sealant, facilitate tooling, and help resist indentation and sag. They may also serve as a bond breaker, preventing the sealant from adhering to the back of the joint. Backup materials for concrete masonry joints are commonly flexible foams, which are compressed into the joint using hand tools (see Figures 1a and 1b).

Backup materials for control joints must be compressible to accommodate masonry expansion (joint shrinkage), and must recover when the masonry shrinks (joint expands).Because the backup also needs to maintain contact with both joint faces when the joint expands, it is compressed when initially installed. Closed-cell backups should be sized 1¼to 1the joint width, so they are compressed 25% to 30% when placed in the joint. Open-cell backups, which are less stiff than closed-cell, should be sized 1½times the joint width, so they are compressed about 50% of their undisturbed width when installed.

Bond Breakers

Bond breakers prevent three-sided adhesion of the sealant (i.e. from adhering to the back of a raked joint or to the backup), allowing the sealant to freely deform in response to building movements (see Figure 1c). Because many backup materials act as bond breakers, a separate bond breaker material is not always required. When it is, polyethylene tape, butyl tape, coated papers and metal foils can be used as well as polyurethane, polyethylene and polyolefin foams. Liquid-applied bond breakers are not recommended because of the likelihood of contaminating the sealant adhesion surface.


Primers, applied to the joint surfaces prior to sealant installation, are sometimes recommended to improve the sealant’s bond strength. In addition, some primers can tolerate application to damp masonry surfaces.

Check the sealant manufacturer’s recommendations for the particular sealant under consideration to determine whether or not a primer should be used on a masonry substrate. To ensure the primer and sealant will be compatible, use the primer recommended by the sealant manufacturer for the sealant being used.

Primer is applied by brush, roller or spray, and typically must dry or cure before sealant application. The recommended elapsed time between primer application and sealant application varies with type of primer, temperature and humidity.

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Figure 1—Common Sealant Configurations


Like most materials, joint sealants should be installed in accordance with manufacturer’s instructions. Elements that are due special consideration, such as sealant depth and surface preparation are discussed in more detail below.

It is typically recommended that joint sealants not be applied during rain or snow, and that the masonry be clean and dry at installation. Installation temperature, i.e., the temperature of the masonry when the sealant is applied, may also be a consideration in some cases. Sealants installed at very low temperatures undergo compression as the wall warms up tothe mean temperature, while a sealant installed at a high temperature is placed in tension at the mean temperature. For these reasons, it is desirable to have the installation temperature close to the mean annual temperature, although an in- stallation temperature range of 40° to 90°F (4.4 to 32.2°C) is generally considered acceptable for most applications, unless otherwise specified by the sealant manufacturer (ref. 6). Note that the masonry surface temperature may greatly exceed the ambient air temperature, especially on dark-colored and/or south- and southwest-facing walls in the sun.

Sealant Width and Depth

Sealant shape factor refers to the mean width versus mean depth of the sealant as installed in the joint. This ratio is important because it affects the amount of strain the sealant is exposed to as the joint moves, as well as the amount of sealant required to fill the joint (see Figure 1d). Sealants exposed to less strain can typically be expected to have a longer life, all other factors being equal. As illustrated in Figure 2, wider and shallower sealant profiles generally reduce strain and require less sealant.

In the field, sealant shape factor is controlled by varying the depth of the sealant, because the width of the joint is fixed at that point. The depth of sealant in the joint is typically controlled via the use of a backup material. Sealants that have a higher depth to width ratio tend to stretch more readily with joint movement, whereas with lower ratios the tendency is for the sealant to tear when subjected to movement. In general, for joint widths from¼to½in. (6 to 13 mm) the joint depth should be no more than the width of the joint. After the sealant is tooled, the minimum thickness of the sealant at the midpoint of the joint opening should not be less thein. (3 mm) and the sealant adhesion dimension no less than¼in. (6 mm) (refs. 1, 2). The required thicknesses also should be verified with the sealant manufacturer.

Figure 2—Effect of Sealant Shape Factor on Sealant Strain

Joint Preparation

For all control joints, mortar should be raked out of the vertical joints on both sides of the panels. The mortar should be raked out at least¾in. (19 mm) to allow for a backup material and sealant (in. (9.5 mm) if no backing is used). This also assures a plane of weakness at the control joint. Mortar in the control joint may also be totally omitted to ensure freedom of movement.

Proper surface preparation prior to sealant installation improves bond between sealant and masonry, and minimizes adhesion failures. Follow the sealant manufacturer’s recommendations regarding cleaning and/or priming the concrete masonry surface prior to applying sealant.

Backup materials must be installed to the proper depth in the joint tocontrol the depth of sealant. Tools for placing backer materials can help ensure correct placement. Any tools used for placement should have a smooth surface adjacent to the backup, to avoid puncturing or otherwise damaging the backup material during placement.

Applying Sealant

Sealants may be either single- or multi-component. Multi-component sealants require thorough mixing, in accordance with the manufacturer’s instructions, to ensure uniform curing and to avoid over-mixing. Once mixed, the sealant has a limited pot life, so batch sizes should be matched to what can be installed within the pot life.

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Masonry joint sealants are typically installed using a common caulk gun, with a tip the same size as the width of the joint. The caulk gun should be held at an angle of about 45° to the wall face, and moved slowly and consistently. Filling joints from bottom to top helps avoid trapping air as the sealant is placed.

Immediately after the joint is filled, the sealant should be tooled to a concave shape. Tooling helps ensure intimate contact between the sealant and masonry, consolidates the sealant, provides a concave profile and improves the appearance of the joint. The hour-glass shape shifts peak stresses away from the adhesion surface and to the middle of the sealant joint during joint movement. Most sealant manufacturers recommend dry-tooling for the best results.


Properly maintained joint sealants will help maintain the water penetration resistance of the building envelope. Sealant materials cannot be expected to have the same life as a masonry building. For this reason, the sealant condition should be inspected on a regular basis, perhaps when the facade is cleaned, and repairs made as needed. Manufacturer’s recommendations should be used as a guideline to estimate sealant life. However, sealant life will vary greatly with exposure and the quality of the initial installation.

Because joint sealant adheres better to properly prepared surfaces, the old or deteriorated sealant should be completely removed from the joint and the joint cleaned prior to reapplication. Minor repairs can be made by cutting out the defective area and reapplying sealant of the same type. Sealants can be removed using a sharp knife to sever the sealant from the masonry. Although some manufacturers recommend more aggressive cleaning methods, such as sand-blasting or grinding, care should be taken when using these methods. For more detailed information on sandblasting, see TEK 8-4A, Cleaning Concrete Masonry, (ref. 7).

Once the joint is properly prepared, sealant can be installed as described above for new construction.


  1. Standard Guide for Use of Joint Sealants, ASTM C1193-13. ASTM International, 2013.
  2. Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width, ASTM C1472-10. ASTM International, 2010.
  3. Crack Control in Concrete Masonry Walls, TEK 10-1A. National Concrete Masonry Association, 2005.
  4. Control Joints for Concrete Masonry Walls – Empirical Method, TEK 10-2C. National Concrete Masonry Association, 2010.
  5. Design for Dry Single-Wythe Concrete Masonry Walls, TEK 19-2B. National Concrete Masonry Association, 2012.
  6. Standard Specification for Elastomeric Joint Sealants, ASTM C920-11. ASTM International, 2011.
  7. Cleaning Concrete Masonry, TEK 8-4A. National Concrete Masonry Association, 2005.

NCMA and the companies disseminating this technical information disclaim any and all responsibility and liability for the accuracy and the application of the information contained in this publication.


backup materialbond breakerconstructioncontrol jointsjoint sealantsmaintenancemovement jointsprimersealantsealant backingsealant designsealant geometrysealant installationsealant joint

(Video) Control joints and fire resistance



The best option for sealing expansion joints is a flexible silicone sealant like Concrete Elite from Silicone Depot. Concrete Elite lasts up to 10x longer than common polyurethane sealants.

What is the best sealant for concrete joints? ›

The best option for sealing expansion joints is a flexible silicone sealant like Concrete Elite from Silicone Depot. Concrete Elite lasts up to 10x longer than common polyurethane sealants.

What are the different types of concrete joint sealant? ›

There are three classes ofjoint sealant materials: preformed neoprene (used only in new construction), silicones, and "all others." VDOT uses only silicones and hot-poured materials in repair work. No cold-poured materials are used. In new construction, only preformed neoprene or silicones are used.

What is the best caulk for masonry control joints? ›

The best options for brick wall expansion joint sealant are polyurethane and silicone. Both are extremely flexible and are ideal for securing your building from movement due to temperature change.

What type of joint is typically required in a concrete masonry wall? ›

Control joints are typically required in exposed above grade concrete masonry walls, where net aesthetic shrinkage cracking may detract from the appearance of the wall, and to limit moisture or air infiltration.

What is a Type N sealant? ›

Sikaflex® Tank N is a 1-component, moisture-curing, elastic joint sealant. High chemical resistance. High mechanical resistance. Movement capability of ± 25% (ISO 9047)

What is the difference between joint filler and joint sealer? ›

Joint Sealer: Exterior use, high flexibility, installed in hourglass shape using backer rod, and prevents water intrusion beneath a concrete slab. Joint Filler: Interior use, low flexibility, installed full depth (normally don't use backer rod), and protects the edges of the concrete joints from chipping and spalling.

What is the difference between Type S and Type M joint sealant? ›

Type-M sealants are typically faster-curing and often have better durability, flexibility, and adhesion properties than Type-S, but introduce quality control concerns related to their preparation and frequently shorter installation working times.

What are the three 3 types of sealant? ›

There are several types of sealants are: Silicone based sealants. Urethane based sealants. Acrylic based sealants.

What are the 2 types of joint sealants? ›

In construction, the seven most common types of sealants are:
  • Water based Latex. Popular for residential use because of the ease of application and ability to adhere to most substrates. ...
  • Acrylic. ...
  • Butyl. ...
  • Polysulfide. ...
  • Silicone. ...
  • Polyisobutylenes. ...
  • Polyurethane.
Jun 17, 2019

What method seals off cracks and joints in masonry walls? ›

Brick caulk, also referred to as brick mortar caulk, acts as a seal that makes joints waterproof and weatherproof. Brick caulk seals joints and closes up any gaps between concrete and masonry. Owing to the nature of its applications, brick caulk must be able to handle movement and not crack under stress.

What caulk is best for exterior concrete? ›

The best exterior caulks are silicone or silicone-latex. These products are excellent for caulking windows and doors. They can be used on trim and siding, as well.

What is Type N mortar? ›

Type N is the DIYer's mortar mix of choice. Engineered for laying brick or soft stone in above-ground applications, pro-grade Type N mortar delivers extended workability and high performance for your masonry projects. Product Details. Use for laying brick or soft stone above ground.

What is the difference between Type S and Type N mortar? ›

Type N mortar is a general-purpose mortar that provides good workability and serviceability. It is commonly used in interior walls, above-grade exterior walls under normal loading conditions, and in veneers. Type S mortar is used in structural load-bearing applications and for exterior applications at or below grade.

What is the difference between Grade P and Grade NS sealant? ›

Grade P sealants are used for horizontal applications and generally contain sealants for traffic use. Grade NS sealants are used for both traffic and non-traffic conditions, mainly for vertical joints and sloping horizontal joints.

What is Type C sealant? ›

P/S Class C is an integral fuel tank sealant. It has a service temperature range from -65°F (-54°C) to 250°F (121°C), with intermittent excursions up to 275°F (135°C). This material is designed for brush and fay sealing of fuel tanks and other aircraft fuselage sealing applications.

What is Type 5 sealant? ›

GENERAL. Crafco RoadSaver CA Type 5 is a hot-applied, asphalt-based product used to seal and fill cracks and joints in asphalt and Portland cement concrete pavements in cool climates.

How long does concrete joint sealant last? ›

Not very durable, they last only around 5 years. Their poor durability make them unsuitable for outdoor projects. Polyurethane sealants are an organic building material. Because of their organic nature, they tend to degrade quickly.

Is silicone or hot pour joint sealant better? ›

In general, hot-poured sealants provide 3 to 8 years of service life after installation, silicone sealants provide 8 to 10 years of life, and preformed seals may provide up to 20 years of service (ACPA 2018a).

Should concrete joints be sealed? ›

Joint sealing is an essential step in maintaining concrete structures, such as parking garages, concrete buildings, and sidewalks. Expansion joints between sections of concrete strategically control where cracks occur in the concrete. These joints need to be sealed to work effectively.

Which mortar is stronger Type S or Type M? ›

There are three widely produced types of mortar: Types M, S and N. Type M will achieve a compressive strength of 2500 psi at 28 days. Type S will yield 1800 while Type N yields 750. By way of reference most general concrete is in the 4000 psi range but can go as high as 8000 psi for special applications.

How do I choose the right sealant? ›

The two most important factors to keep in mind when selecting a caulk or sealant are the temperature range and moisture level at the site of application. Let's explore the unique properties and benefits of some of the most common products to ensure you find the best fit for a variety of indoor and outdoor projects.

What is Class 25 joint sealant? ›

A sealant's expansion and contraction capabilities is defined by one of five primary classes. The higher the class designation, the more flexible the product. For example, a Class 25 sealant allows for up to 25% expansion or contraction of the joint without failure.

What are the examples of joint sealant? ›

Common sealants include silicone, acrylic, urethane, butyl and other polymeric types.

What is the toughest sealant? ›

Adiseal has proven to be the record breaking strongest adhesive in an independent adhesive strength test.

What is a Type 1 sealant? ›

Crafco Parking Lot Sealant Type 1 is a hot-applied asphalt based product used to seal and fill cracks and joints in asphalt or Portland cement concrete pavements in cold to hot climates.

What are urethane joint sealants used for? ›

It is used in joints between prefabricated building elements, in joints of rainwater collection pipes on roofs and in rain gutters, insulating joints between precast concrete blocks and sealing of joints of aluminum pipes in HVAC (ventilation) sector.

What are elastomeric joint sealants? ›

Elastomeric Joint Sealants are cold-applied elastomeric single or multi-component materials used for sealing, caulking, or glazing operations on buildings, plazas, and decks for vehicular or pedestrian use, and types of construction other than highway and airfield pavements and bridges.

What is concrete joint sealant? ›

The POURTHANE joint sealant line is designed for sealing concrete and metal joints in a variety of applications, including sidewalks, balconies, pavement, terraces, warehouses, factories, civil structures, plazas, and pitch pans.

Should concrete walls be sealed? ›

Applying a Concrete Sealer Is Important

If you avoid sealing foundation cinder blocks before water issues start, they can and may become unsealable in the future.

What is the best sealant for masonry cracks? ›

Foundation, walls, and masonry.

That means Loctite PL Concrete Non-Sag Polyurethane Sealant is the right choice: it's a concrete caulk that is suitable for repairing cracks in vertical and horizontal surfaces and bonds to concrete, brick, stucco, metal, wood, vinyl, fiberglass, and other substrates.

How do you repair masonry joints? ›

  1. Chip out damaged mortar with a utility chisel.
  2. Wet work area with a hose.
  3. Mix dry mortar with water according to product directions.
  4. Fill horizontal joints first then vertical joints.
  5. Pack joints tightly to ensure waterproof seams.
  6. Wait until you can leave a thumbprint in mortar to finish.

What caulk is used for concrete joints? ›

Fill the crack with urethane caulk, similar to what you would use for driveway caulk. It works perfectly as a concrete expansion joint sealant.

What caulk to use for sealing concrete cracks? ›

Loctite PL Polyurethane Concrete Crack and Masonry Sealant is a premium quality, commercial grade sealant developed especially for forming permanent, water and weatherproof seals in all exterior gaps and joints.

Does 100% silicone caulk stick to concrete? ›

It can be used on the following materials or surfaces: Aluminum. Concrete. Ceramic.

What is the best concrete joint material? ›

Epoxy and polyurea-based joint fillers are two of the most popular filler solutions. They help extend the lifetime of concrete floors and allow them to perform as intended throughout their usable years.

What material is used between concrete joints? ›

Epoxy. Epoxy is often used to manufacture expansion joints because of its durability and high strength, which means it can resist excess force and stress. Other benefits include its low viscosity, which makes it easy to use, and stable performance in various temperatures.

What are the seams in concrete called? ›

Contraction joints (sometimes called control joints) are used in unreinforced and lightly reinforced slabs-on-ground to minimize random cracking.

When should Type N mortar be used? ›

Type N mortar is a general-purpose mortar that provides good workability and serviceability. It is commonly used in interior walls, above-grade exterior walls under normal loading conditions, and in veneers. Type S mortar is used in structural load-bearing applications and for exterior applications at or below grade.

Can Type N mortar be used outside? ›

Type N is described as a general purpose mortar mix and can be used in above grade, exterior and interior load-bearing installations. It is also associated most commonly with soft stone masonry. This type is ideal for anything that is exposed to severe weather and high heat.

Why is my Type N mortar cracking? ›

Cracking can result from a variety of problems: differential settlement of foundations, drying shrinkage, expansion and contraction due to ambient thermal and moisture variations, improper support over openings, the effects of freeze-thaw cycles, the corrosion of iron and steel wall reinforcement, differential movement ...

What is Type N masonry cement used for? ›

Usage. Type N Masonry Mortar is recommended for general use in non-load-bearing walls, as well as in exterior veneer walls not requiring high strength. Type N Masonry Cement or Type S Masonry Cement can also be used in parging and stucco work. DO NOT use masonry cements for concrete jobs.

How thick is Type N mortar? ›

joint (vertical edge) and press the block/brick down into the mortar and place into position against the previously laid block/ brick. Mortar joints should be a consistent ⅜ in. (10 mm) thick.

Can you use Type N mortar below grade? ›

Type N mortar is suitable for above-grade load-bearing exterior walls and parapets as well as load-bearing interior walls. It could also be used as an alternative for most other masonry situations, such as non-load bearing interior walls, exterior walls below grade, or tuckpointing open joints when warranted.

Is it better to roll or spray concrete sealer? ›

For large scale applications sprayers are faster and more efficient; whereas paint rollers are less expensive and are more readily available. If you are going to be applying a decorative acrylic sealer or an epoxy floor coating it is best to use a 1/4″ or 3/8 nap roller.

How do you seal a leaking concrete joint? ›

The most widely used methods for sealing leaks in concrete joints and cracks are placing chemical grouts – typically water-activated polyurethane grouts. They are in a liquid form, react with water, and form a foam end product.

Can you seal concrete too much? ›

Heavy coats of sealer, or a buildup of sealer applied numerous times over the years, will cause moisture to become entrapped under the sealer and, in time, the sealer loses adhesion from the concrete.

Do you caulk or seal concrete first? ›

Caulking cracks and breaks helps prevent further damage to your concrete from water, freeze-thaw cycles, and other factors. After the concrete is clean, completely dry, and any cracks are caulked, we apply a penetrating sealer to the surface of the concrete with pressurized sprayers, ensuring an even coating.

What is the downside of sealing concrete? ›

One of the biggest disadvantages of concrete driveway sealing is the cost. The materials and labor required to seal a concrete driveway properly can be expensive. In addition, concrete driveways that are improperly sealed can trap moisture underneath the surface, which can lead to problems such as mold and mildew.

How many coats of concrete sealer should I use? ›

Concrete sealers are best applied in two thin coats. The first coat of sealer acts like a primer. Most of it will disappear into the concrete surface, and the concrete will probably look fairly unattractive after the first coat. The second thin coat will provide an even finish, color enhancement and gloss.

Should I use solvent or water based sealer for concrete? ›

Solvent-based sealers will generally darken your concrete more than a water-based sealer. This can be ideal when you have a decorative effect you are trying to achieve, but water-based sealers can give a more natural appearance to your concrete. This is ideal when working with uncolored gray concrete.

What is a powerful method to stop leakage in concrete? ›

Polyurethane crack injection is positively the most effective leaking crack repair method in concrete.


1. SCMA Concrete Masonry Academy: Designing for Moisture Protection in Masonry Walls
(Southeast Concrete Masonry Association)
2. How to Build a Block Wall DIY #3
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4. How to Build A Concrete Block Wall
5. You Want To Hang On Concrete Walls? Here's How To Drill Into Concrete the DIY way | GardenFork
6. How to Build a Block wall, Texture Stucco and Gate!
(Odell Complete Concrete)


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