What Is A Joint Sealant In Construction?

What Is A Joint Sealant In Construction
Application – Sealants are used to seal joints and openings in various architectural applications, which include:

High- and low-rise commercial buildings:

Exterior and interior perimeter of windows Roofing and flashing penetrations and terminations Building and material expansion joints Interior perimeters of doors, baseboards, and moldings

Plazas and parking deck joints in traffic surfaces Joints between tilt-up concrete exterior panels Airport runway and apron pavement joints Bridge and highway pavement joints Sidewalks, parking lots and flat work joints Water and wastewater treatment facility joints (including in submerged environments) Part of a fire and smoke stop assembly for joints and penetrations Structural sealant glazing

What is a joint sealant?

Applications – Sealants are used to seal joints and openings in various architectural applications, which can include the following:

  • High- and low-rise commercial buildings:
    • Exterior and interior perimeter of windows
    • Roofing and flashing penetrations and terminations
    • Building and material expansion joints
    • Interior perimeters of doors, baseboards, and moldings
  • Plazas and parking deck joints in traffic surfaces
  • Joints between tilt-up concrete exterior panels
  • Airport runway and apron pavement joints
  • Bridge and highway pavement joints
  • Sidewalks, parking lots, and flat work joints
  • Water and wastewater treatment facility joints (including in submerged environments)
  • Part of a fire and smoke stop assembly for joints and penetrations
  • Structural sealant glazing

Is joint sealant the same as caulking?

Caulk vs Sealant In fact, the terms ‘caulk’ and ‘sealant’ are often used interchangeably, since both are used to fill joints and seams. However, the biggest difference between caulk and sealant is elasticity. Caulk is more rigid than sealants when dry.

What does sealant do in construction?

How to Choose the Best Sealant for a Construction Project Sealants are commonly used in the construction industry to fill cracks and openings and seal joints. They provide a barrier to air, water, moisture, gas, noise, dust and smoke. Although they generally represent less than 1% of the cost of a building or renovation project, they are extremely important for the waterproofing of the building.

Where are joint sealants used?

Building joints move in three different ways that affect the sealant in the joint: expansion, contraction, and shear. Modern commercial structures rely heavily on joint sealants to prevent water damage to buildings and their contents. While residential buildings use water-shedding techniques such as sloped roofs, lap siding, and overlapping flashings, many commercial designs don’t; if a joint sealant fails, there is little or no barrier to leakage.

  1. Unfortunately, in today’s building environment, there are many points in the design and construction process where bad judgment or bad behavior results in sealant failure.
  2. Read the following for tips on how best to avoid these situations.
  3. Common Uses Joint sealers are used to close open joints to keep water and air out (both exterior and interior); for appearance and cleanability (in interior surfaces where water resistance is not an issue); and to reduce sound transmission through cracks (usually interior and internal to composite assemblies).
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If none of the above considerations is applicable, joint sealers are probably not necessary. Although there are many types of joint sealers, this review covers joint sealants only—pourable or gunnable material of mastic consistency that sticks to each side of a joint.

  • Exterior. Most modern homogeneous rigid exterior substrates are purposely jointed, to allow movement without damage to the material.
  • The two principal causes of movement are thermal expansion and contraction and seismic movement.
  • Some substrates, such as traditional shingling, can be overlapped to allow rainwater to run off while also allowing movement—these usually won’t need sealing.

Others incorporate the seal into the product design, such as metal panels with edge joints designed to prevent water infiltration. Other combinations of exterior materials are simply different and, as a result, seldom form a watertight joint without the addition of a sealer.

exterior wall joints (masonry, concrete, plaster/stucco, EIFS, for example); door and window frames; concrete paving joints; metal flashings; roof joints; and seismic movement joints.

Interior. Joints indoors don’t usually go through the thermal fluctuations that exteriors do, but they are also often jointed for other reasons. Gypsum board and plaster assemblies, for instance, often require control joints to prevent cracking. Interior joints are usually sealed to keep dirt out and make them look better. The principal interior substrates that are sealed are:

gypsum board; plaster; floor control and expansion joints; and kitchen and bathroom wet joints.

To Avoid Failures

Choose the correct design solution. The life span of even the best sealer materials available is finite—usually less than the expected building life span. If failure of the joint seal would be very costly, a water-shedding solution might be a better solution. Estimate the actual amount of movement correctly. Consider the width of the joint, the distance between joints, and the thermal range. ASTM C 1472 can help. Joint movement is of three types: expansion and contraction (the joint gets wider or narrower); shear or lap movement (the faces of the joint slide past each other, and the sealer undergoes twisting and stretching but no compression); and expansion, contraction, and lap shear, all at once. ( See diagrams.) Choose a sealant product that will withstand the movement expected. Most joint sealer mistakes relate to movement— misjudging the actual amount of movement or selecting a product that won’t withstand movement. Movement capability is the relevant product characteristic. Choose a sealant that will withstand the environmental conditions. The second most common cause of product failure is degradation by water and weather (including indoor wet areas). Specify the sealant product correctly. The two most common ways to specify sealants are, one, by listing the manufacturer and brand name(s) of acceptable products, and, two, by specifying characteristics by description and/or by reference to voluntary standards. If both techniques are used for the same product, be sure that they are not contradictory. Specify the scope of sealant work completely. Implementation mistakes occur most commonly because of a failure to completely identify the joints to be sealed and the product(s) to be used for each. The extent of sealing work is not always apparent from the drawings. So, it is commonly necessary to describe the extent of the sealing work in words. This may be placed on the drawings, as notes or a schedule, or may be included in the specification. Regardless of methodology, the important point is that the description fully describe the extent of the work by identifying all the joints to be sealed. Specify execution correctly. Most joint sealers require expert installation, without which failure is likely. Require installers to follow the manufacturer’s installation instructions and specify reputable manufacturers who provide detailed instructions (do-it-yourself products don’t usually come with detailed instructions). Take care not to introduce conflicts by specifying execution that contradicts manufacturers’ instructions. Specifying Sealants Joint sealants are usually specified in a single section describing products, execution, and administrative requirements: 07920—Joint Sealants (MasterFormat 1995) 07 92 00—Joint Sealants (MasterFormat 2004) Concrete pavement joint sealants are sometimes specified in a separate section: 02750—Paving Specialties 32 13 73—Concrete Paving Joint Sealants When more than one type of sealant is specified, the drawing notes or a schedule must identify which ones are to be used in which locations. Use terminology that will explicitly “tie” the product in the schedule or on the drawings to the product in the specification. Some people like to give each specified sealant a Type A–, Type B–style designation. This technique has the advantage of allowing the exact type of sealer to be changed by altering the specification, without any need to change the drawing/schedule notation. Some statements that might appear in a sealant schedule: “Control joints in brick veneer: Sealant Type A.” “Joints between concrete columns and brick veneer: Sealant Type A.” “Joints between window and door frames and brick veneer: Sealant Type A.” “Control joints in interior gypsum board: Acrylic latex sealant.” “Joints between kitchen and bath counter backsplash and wall: White silicone sealant.” In some cases, the sealant is to be furnished and installed by the installer of the product that is to be sealed. For instance, the window specification might require the window installer to complete the installation by sealing around the window. In that case, the sealant and the sealing work can be specified in the window section. Alternatively, the sealant product and installation may be cross-referenced from the window section to the joint sealers section. Whenever there are a lot of instances like this on the project, it’s more convenient to cross-reference to eliminate repetitive language. Although installation requirements for sealants should be specified, it is relatively safe to rely on a statement to “install in accordance with manufacturer’s instructions.” Most manufacturers will not stand behind their product if it is not installed in accordance with their instructions and recommendations. ASTM C 1193 covers typical applications in great detail as help to the specifier, but referencing it as a specification requirement is basically useless; there are too many options to be able to enforce any of them. See the web link at the article’s end for other references, including a free guide from the U.S. government.

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What is the difference between joint sealant and backer rod?

Backer Rod for Expansion Joint and Crack Repair is a soft and pliable filler designed to partially fill concrete expansion joints or cracks in concrete before applying joint sealer caulk. This material is non-absorbent and allows the depth of the concrete joint sealant to be controlled.

  1. Backer rod comes in various sizes and will fit tightly into an opening to remain in place and contain self-leveling caulk. George L.
  2. Wilson carries backer rod from vendors such as Armacell and Nomoco, as well as tools and accessories to use backer rod.
  3. Expansion joints are generally joints or spaces left between slabs or construction elements of the same material to facilitate expansion and contraction due to changes in ambient temperatures.

Expansion joint sealant materials are chosen for their ability to absorb impact and expand or contract along with the rest of the structure without cracking or separating. These sealing agents include several types of fluid or gel epoxies. George L. Wilson carries a range of expansion joint materials such as Fibre Expansion Joint, Plastic Joint Materials such as Speed-e-Joint and Snap-Cap from WR Meadows as well as Rubber Expansion Joint Material from Reoflex.