079200 – JOINT SEALANTS

Chapter 4 – Implementation in the Construction Documents

This module is about pulling all you've learned so far together, including design considerations, product selection, and implementation on the drawings and in the specifications.

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At least two sealant products are likely to be required for any ordinary building -- one for indoors and one for outdoors. For projects with more different materials and exposures, many more sealant types could be necessary. In addition, it is likely to be extremely difficult to identify all the relevant joints by labels on the drawings. So, implementation involves several functions:

  • Scope Definition:  How to tell the contractor which joints to seal.
  • Application Definition:  How to tell the contractor which joints to seal with which sealants.
  • Product Definition:  How to tell the contractor which products to buy and install.

Scope Definition

The most common implementation mistake is failure to completely identify the joints to be sealed. The complete extent of sealing work is usually not apparent from the drawings. An exterior wall expansion joint is usually shown on an elevation, but would the drawings always show the sealant between the bottom of a water closet and the floor? Sometimes a detail shows a cross-section of a joint and may reference the type of sealer, but who wants to spend the time detailing each and every joint. And what if you left one out? So, we're going to assume that it will be necessary to describe the extent of the sealing work in words. The words may be placed on the drawings, as notes or a schedule, or may be included in the specification.

If there are only an interior and an exterior sealant, the scope definition is pretty easy.

"Exterior Joints:  Seal all open joints, whether or not the joint is indicated on the drawings."

"Interior Joints:  Seal all open joints, whether or not the joint is indicated on the drawings."

I'm sure you can already find some fault or loophole in these statements. The first is "what's the definition of an open joint." The second is that if the project has both wet and non-wet interior areas, there are three different applications with possibly two different sealants (assuming that the exterior sealant could be used for the interior wet areas). So, the scope description is already inadequate because it doesn't specify which type of sealant to use for each application.

Application Definition

The application definition can be phrased as "where to put what." You may recognize this as an expression that also refers to a "schedule." Adding the products to the scope definition does produce the equivalent of a schedule, although it need not be in tabular format.

"Exterior Joints:  Seal all open joints, whether or not the joint is indicated on the drawings. Use X [e.g. one-part nonsag polyurethane sealant].

"Interior Joints:  Seal all open joints, whether or not the joint is indicated on the drawings.

"Non-Wet Areas:  Acrylic emulsion latex sealant.

"Wet Areas:  Same sealant as specified for exterior joints."

Sealant Schedule

Since the essential parts of a sealant schedule are the scope definitions and the application definitions, we're going to use the term "schedule" even though it is usually not in tabular format. A schedule can be expanded with as much detail as desired, but it should refer to the sealant types using the terminology that is used (or will be used) in the specification section. That is, don't use product brand names in the schedule, to make later revisions easier.  Here are is a much more comprehensive example:

"Scope of Joint Sealing:  Seal all open joints, whether or not the joint is indicated on the drawings, unless specifically indicated not to be sealed.

"Do not seal joints indicated to be treated with manufactured expansion joint covers.

"Do not seal seismic movement joints.

"Do not seal joints between suspended lay-in ceilings and walls.

"Exterior Joints:  Seal all open joints, whether or not the joint is indicated on the drawings, unless specifically indicated not to be sealed or is to be treated with some other type of sealing device.

"Unless Otherwise Specified:  Sealant Type X [e.g. one-part nonsag polyurethane sealant].

"Joints to be sealed include but are not limited to:

"Wall expansion joints.

"Joints between door and window frames and adjacent construction.

"Pavement joints:  Sealant Type Y

"Cooling tower basin:  Sealant Type Z.

"Interior Joints:  Seal the following joints:

"Wall Joints in Non-Wet Areas:  Acrylic emulsion latex sealant.

"Wet Areas:  Same sealant as specified for exterior joints.

"Joints to be sealed include but are not limited to:

"Wall joints.

"Floor and wall joints in food service washdown area:  Sealant Type Z."

Default Product Application

The Default Product Application is a scheduling technique that saves time as well as reduces omissions. In the schedule, one product is defined as to be used unless another product is specified. The default product can be listed at the top, or all the special applications can be listed first with the "unless otherwise specified" product listed at the bottom. For example:

"Use Sealant Type X unless otherwise specified.

'Pavement joints:  Sealant Type Y

'Cooling tower basin:  Sealant Type Z.'

Or

'Pavement joints:  Sealant Type Y

'Cooling tower basin:  Sealant Type Z.

'All other joints:  Sealant Type X.'

During product selection, you may have found that 3 or 4, or more different joint types with different exposures can actually be sealed with the same sealant. Instead of listing all those applications, treat that sealant type as the default, and list the applications needing a different sealant as exceptions. One way to do this systematically is the following:

  1. Identify the exterior joints with the most extreme movement and select a generic sealant for them - this is the default exterior sealant. For interior joints, assume that the default sealant will be acrylic emulsion latex.
  2. Using the characteristics of the sealant selected identify any other joints that CANNOT be sealed with this sealant. Identify the factor that makes that sealant unsuitable and look for a substitute.
  3. Use as few different types of sealants as possible. This not only saves time in preparing the construction documents, but reduces contract administration time.

Scope Exceptions

Since scope is often difficult to define by listing each and every joint, the definition starts with the equivalent of "seal every joint unless we say otherwise" and then lists the exceptions. This is usually expressed in that order -- a definition of everything, followed by exceptions.

"Scope of Joint Sealing:  Seal all open joints, whether or not the joint is indicated on the drawings, unless specifically indicated not to be sealed.

"Do not seal joints indicated to be treated with manufactured expansion joint covers.

"Do not seal seismic movement joints.

"Do not seal joints between suspended lay-in ceilings and walls."

This is a reasonable approach for exterior sealing, because it's reasonable to want to seal up the entire building.  However, it may not be necessary to seal every interior joint. In that case, this technique is reversed -- the assumption is that no interior joints are sealed unless explicitly so stated.

Where to Put the Schedule

It doesn't really matter whether the sealant schedule is located on the drawings or in the specification. The important point is that the schedule needs to fully describe the extent of the work by identifying all the joints to be sealed and what to seal them with.  

In the specification, the schedule can be placed at the end of PART 3 (the traditional location) or at the beginning of PART 2, where bidders will see it first. Placing the schedule at the beginning of PART 2 is also a logical thought progression for the specifier -- there should be no sealants specified later in PART 2 that are not in the schedule.

Specifying the Products

The products are most likely going to be specified in Section 079200 Joint Sealants (from CSI/CSC MasterFormat™).

For each different sealant needed, a product specification is needed, with a name to tie it to the schedule. Using Type numbers is a neat way to do this -- you can still call the sealant by its generic name but add the Type number.  In an office master, Type numbers might be fill-in-the-blanks to allow the same sealant to be, for example, Type B on one project and Type Z on another. Although it would be tidiest for the Type numbers to be in alphanumeric order, that's not essential. You can also see that if you want them in the right order but don't want to reorganize the product specifications, it would be relatively easy to change the Type numbers in the schedule, because you made a compact and efficient schedule by using the default product technique. Examples:

"Type X - General Purpose Exterior Sealant:  One-part, nonsag, ASTM C920 …."

"Type A - General Purpose Interior Sealant:  Acrylic emulsion latex, ASTM C834 …."

Complete the product specification by defining it sufficiently. The two most common ways to specify sealants are:

  • List the manufacturer and brand name(s) of acceptable products
  • Describe the generic product type and its required characteristics.

If both techniques are used for the same product, be sure that they are not contradictory. A description can cite the relevant ASTM standard, but that is not usually enough. It may be sufficient to refer to ASTM C834 for acrylic emulsion latex, but if you want to cite ASTM C920, be sure to include the relevant Grade, Class, and Uses, or you may not get the type of elastomeric sealant you really want.

An example of using both techniques:

"Type X - General Purpose Exterior Sealant:  One-part, nonsag, ASTM C920 Grade NS, Class 25, Use M, G, and A.

"Color:  Custom colors to match adjacent surfaces.

"[Other characteristics not defined by ASTM C920.]

"Acceptable Products:

"Manufacturer ABC, Brand 123.

"Manufacturer DEF, Brand 456."

Accessory Materials

Accessory materials that are typically required for joint sealants include backer rods and bond breaker tape. These can usually be specified as "As recommended by sealant manufacturer" because you don't want to specify something that contradicts the manufacturer's recommendations. The only exception is when most manufacturers give several options and you don't like some of them.

Specifying Execution

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). Do not introduce errors by contradicting manufacturers' instructions in your specifications.

Although installation requirements for sealers 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 not installed in accordance with their instructions and recommendations, so start there. If you want more detail, try ASTM C1193 as a resource, but don't reference it as a specification requirement because it is advice with too many options to be able to enforce any of them.

Sealants Specified in Other Sections

There are several reasons that a joint sealant might be specified in another section:

  1. The sealant is very specific to the main product specified in that section and is unlike any sealant specified in Section 079200.
  2. The sealant is installed by the manufacturer of the main product, in the factory.
  3. The sealant is to be installed by the installer of the main product because he needs to be responsible for that work.

Conditions 1 and 2 are easy -- the sealant and its installation should be fully specified in that section AND NOT in Section 079200.

Condition 3 is trickier. The appropriate sealant can easily be specified in the other section using the Type number or other identifier used in 079200. The problem is a subtle one. Section 079200 says something like "seal all joints unless specified otherwise."  The contractor is going to assign the work of Section 079200 to a particular subcontractor. If the installer of the other product is also to install the sealant for that product, that work is outside the work of Section 079200.  

Even if the conditions of the contract state that the division of the specs into sections is not meant to limit or define the contractor's assignment of subcontracts, the contractor is going to do it that way anyway because it's easier.  Several things can happen:

  • Both the 079200 subcontractor and the other section subcontractor interpret their scope of work correctly and include the installation. They get it worked out in the end, but the owner has probably paid twice for the same work.
  • Both subcontractors interpret the installation of the sealant in the other section as NOT in their scope of work -- one erroneously, one correctly. When someone discovers that neither have installed that sealant, a lot of finger pointing occurs and a change order is proposed. The owner rightly objects that the work is clearly indicated in the construction documents.
  • Any other combination of errors.

So what is needed is a way to define the scope effectively in Section 079200 so that no joint is left out, but avoid having to list a scope exception for every instance where sealants are installed as part of the work of other sections.  Wow!  The traditional technique for dealing with this is to include in Related Requirements statements like this:

"Section XX XX XX:  Installation of sealants for YYYY, using products specified in this section."

That's pretty good, provided you list every single one of these instances. If you've got a method of searching all the spec sections for mention of joint sealants, that might save enough time to justify trying to list every instance.

Another way to do it is to add an exception to the scope definition in Section 079200, that says something like "except applications for which installation of joint sealant is specified in another section." This makes it unnecessary to list all the instances. It does make it impossible to know which instances exist without reading all the spec sections. Disputes will still occur because someone involved will not have read all the specs -- but possibly fewer disputes than using the other method.

So, the last thing you need to do before finishing the specifications is to re-check the scope definition in Section 079200 against what the other sections say about joint sealants. Add whatever Related Requirements statements or scope exceptions you feel are adequate to clearly explain who is to do what.

Sealant Applications That Should Not be Specified in Section 079200

The following applications should be specified with the affected work, rather than in the Joint Sealants section:

  • Sealants used as adhesives.
  • Sealers used to join sections of roofing and waterproof membranes.
  • Joint fillers and sealers that must be installed as part of a manufactured or fabricated assembly.
  • Sealants and gaskets used to install glass and plastic glazing, including those for structural glazing.

Review

1. Which part of the construction documents will define the scope of joint sealing and which sealants to use for which joints?

  • The drawings.
  • Part 2 of the specifications.
  • A joint sealant schedule.

2. What is the principal reason for defining the scope of joint sealing in words?

  • To save time.
  • Because otherwise the drawings would have to show each and every joint.
  • Because the Contractor will guess wrong if you don't.

3. What is a "default product application" used for?

  • To provide a definition of which sealant to use if a joint doesn't have a defined sealant.
  • To make it unnecessary to list all types of joints using each sealant.
  • To save time.
  • All of the above.

4. "Type" designations are commonly used for sealant types for accurate referencing in schedules and other sections.  True / False

5. Sealants are commonly specified in other sections besides the main Joint Sealers section.  The principal reason for careful coordination of all these sealants is to avoid disputes, omissions, and double billing.  True / False

Next - Course Completion and Appendix