Unique Problems Insulation Contractors Face with Commercial Facilities

Steve Fisher

September 1, 2013

Commercial buildings can pose a variety of issues
for insulation contractors. Commercial jobs include office buildings, hotels,
schools, hospitals, retirement centers, condominiums, government buildings, and
supermarkets, among others. Of these, hospitals and schools seem to offer the
greatest opportunities in today’s construction market. Examples of mechanical
applications requiring insulation on these projects include: low-pressure
steam/condensate, hot water, cold water, and air-conditioning lines; heating
hot water, supply and return chilled water, and refrigerant lines; and supply
and return outside air and exhaust air systems.

Commercial building projects
typically differ from industrial projects in the following characteristics:

  • Insulation thicknesses must conform to local building codes;

  • Narrower temperature range (+40°F to +300°F);

  • Smaller scope and pipe size;

  • Generally shorter time frame from bid to installation, and from
    installation start to completion;

  • Generally new construction or additions—not maintenance work; and

  • Minimal maintenance can be expected after the installation is completed.

The 3 biggest issues the
insulation contractor faces on commercial jobs are:

  1. Making
    sure the building is enclosed (i.e., the roof is installed and the building is
    water tight) before insulation installation starts. This may not always be
    feasible since the insulation contractor does not control this.

  2. Ensuring
    the design engineer and other trades (pipe/duct mechanical contractors) provide
    clearance between pipes and walls for the insulation thickness specified.

  3. Working
    with the schedules of the other mechanical and plumbing contractors.

When specifying the best insulation for these applications, the design
engineer/contractor first looks at performance compliance, which would include
meeting all state and local building code requirements. The insulation
materials must be able to withstand the temperatures and environmental
conditions of the particular application. Different regions of the
country—e.g., north versus south, or inland versus coastal areas—may require
different materials for the same application because of the different environmental
conditions, such as higher humidity in southern and coastal areas. This is
particularly true for below-ambient systems, such as chilled water, where both
surface condensation (sometimes called casual or intermittent condensation) and
condensation within the insulation area (which can be caused by an inadequate
moisture vapor seal on all joints, longitudinal seams, fittings, hangers, and
termination points) constitute a key concern. These must be addressed in the
design parameters. When the building envelope is not dried-in, it is important
that the engineer specifies insulation materials with low water-absorption
characteristics and insulation systems with a low water-vapor permeability.

After reviewing the insulation
materials, one may find that there are 2 or 3 that meet the performance
criteria needed. Thus, the next step in the selection process is to select the
most cost-effective material, which is often decided by which product is most
easily installed or will last the longest with little or no maintenance.

This article will address the
unique circumstances of commercial buildings that will determine performance
and cost effectiveness.

Note that the building owner
needs to differentiate between lowest first-cost materials and lowest
life-cycle cost materials, since these are often not the same. Then, they must
convey their requirements to the specifying engineer.

On hot systems, the following
materials are often specified and installed:

  • Low-pressure steam and condensate—fiberglass with all-service jacketing
    (ASJ)

  • Hot water—fiberglass with ASJ (hot water is sometimes subcontracted out
    by the plumbing contractor to an insulation subcontractor). In addition,
    closed-cell insulations are sometimes used when the mechanical engineer does
    not want to mix materials on domestic hot- and cold-water applications.

For hot applications,
fiberglass with ASJ has the benefits of performance, ease of installation, and
cost effectiveness.

For below-ambient systems—i.e.,
cold or chilled water—design engineers routinely select closed-cell insulation
materials with an inherent low water vapor permeability value, particularly in
unconditioned spaces, because of their concern over condensation control and
long-term thermal performance. This group of materials would include cellular
glass, elastomeric foam, phenolic foam, polyolefin, polystyrene, and
polyisocyanurate (PIR) foam insulations. Fiberglass continues to be specified
and successfully used on below ambient systems in continuously conditioned
spaces such as occupied offices, where humidity is low and there is less vapor
drive, typically in the northern regions. For unconditioned spaces, it is
recommended that fiberglass with ASJ be covered with a continuously sealed
polyvinyl chloride (PVC) jacket.

Another consideration to take
into account is environmental fluctuations during use in a particular space.
For instance, a conditioned convention center hall may experience major
variations in ambient conditions during loading or unloading, when the shipping
doors are wide open. The proper insulation for this type of condition must be
selected or the building’s systems may face problems. A similar situation can
occur when the convention center is not in use and the HVAC system is turned
off, causing a significant rise in indoor conditions.

In Figure 1 the author shows
some types of insulation materials listed by application. Not all insulation
materials are listed, however; readers should research what is best for their
individual project.

Performance issues unique to below-ambient
systems in commercial buildings that would factor into the material selection
process may include:

  • Susceptibility of mold growth on enclosed piping (behind walls). This is particularly a problem with paper-faced vapor
    retarders in unconditioned spaces. The concern over mold issues in this type of
    application may lead to more expensive and more labor-intensive insulation
    systems being used to reduce potential future problems.

  • Susceptibility of vapor barrier damage in pipe chases where material must
    be applied and slid through penetrations. This would limit maintenance after
    installation. Some insulation materials require the specification of a robust
    jacket capable of withstanding abuse; PVC jacket is sometimes used for this
    reason. Multi-layer (low perm) jackets with easy-to-seal seams that resist
    abuse may be used where maintenance of the system will be limited or
    non-existent.

  • Temperature and humidity not regulated
    uniformly throughout the building may require the use of greater insulation thickness
    to prevent condensation in some parts of the building (e.g., back room or
    ceiling areas).

  • Prevention of water vapor
    condensation/intrusion within the insulation and on the metal pipe and
    equipment surfaces, requiring that all insulation systems be completely sealed
    against water vapor intrusion. In this case, only insulation systems capable of
    being continuously sealed should be selected. An often misleading concept is
    that all jacketing provides a moisture/moisture vapor barrier. Metal jacketing,
    such as aluminum, only provides a moisture vapor barrier if all seams and any
    penetrations (e.g., rivet holes) are caulked; therefore, metal jacketing is
    intended to be protective and not as a vapor retarder material. Additionally,
    PVC jacketing will only be effective as the water vapor transmission barrier of
    the seams. Flexible laminate jacketing, some with a zero permeance rating, must
    be continuously sealed, usually with a compatible, zero permeance, pressure
    sensitive tape.  Rewettable fiberglass cloth provides abuse protection only and
    is not a vapor retarder barrier. For below-ambient systems, the insulation
    beneath the jacketing should provide a moisture vapor barrier on its own.

Installation issues unique to
below-ambient systems in commercial buildings may include:

  • Insulation being installed prior to the building being enclosed. This is
    a quite common, but counterproductive, practice. Closed-cell foam materials are
    capable of withstanding intermittent moisture or high-humidity conditions that
    may be present during the construction of the building, but this is often not
    factored into the engineering design specification. Closed-cell foam insulation
    products are sometimes specified or used for this reason, such as in hotels
    (duct risers).

  • The need for a flexible insulation material for installation around and
    through walls, including air-conditioning lines, chilled water run-outs, etc.
    Note: Air-conditioning lines are typically completed by the
    mechanical/equipment installer.

    ?
    The need to meet a compressed
    installation time schedule. Installation products with adhesive, pre-applied,
    pre-fabricated fittings, or insulation with pre-applied jacketing, are often
    used to shorten the installation time. These products may also reduce the risk
    of failures at the seams and joints of the insulation or the jacketing. Seams,
    joints, jacketing, or adhesives applied in factory-controlled conditions may
    perform better than those applied in the field under varying environmental
    conditions.

  • Ability of the insulation to be slid on the copper pipe in long sections
    (20 inches) to eliminate butt joints and speed installation time, often a
    concern in supermarkets. Note: Supermarkets are generally done by the
    refrigeration contractor.

  • Burial applications that require a load-bearing capacity as well as
    being water tight.

  • Extreme high-humidity applications may require low water-vapor
    transmission insulation and an additional ?low permeance, continuously sealed?
    jacket to prevent long-term water-vapor penetration.

  • Prevention of pipe and equipment
    corrosion, sometimes called corrosion under insulation or CUI, in cold storage
    applications (using ammonia systems) should receive extra care. Polystyrene and
    PIR jacketed sealed with a low permeance vapor retarder have a long history of
    use.

As seen in the examples, there are many reasons an insulation system is
selected for a particular application. Performance parameters should always be
the highest priority, with other factors also coming into play (cost of
material, installation technique, installation ease/time, durability of the
material over time, etc.). Lastly, experienced contractors become familiar with
installing specific materials on certain types of systems. Insulation and
accessory manufacturers are continually trying to refine their products for
better performance and ease of installation. They understand that one insulation
material or one insulation system will not work best for all applications,
which results in niche products for specific applications. Commercial
applications tend to be more diverse and open to variation in design than
industrial applications. Design engineers and insulation contractors should
always be attentive to new products and processes if they want to stay
competitive and provide the best materials for an application.