Have a question about the HMMA, hollow
metal products and applications, building codes or HMMA membership? Below
are some of the questions that are typically directed our way. If you still
have queries after reviewing this section, please contact
us.
Products
and Application FAQS
What is the most commonly
used steel substrate for steel doors and frames?
The three most common steel substrates are cold rolled steel, galvanneal steel
and galvanized steel. Cold rolled steel, suitable for most interior applications,
is untreated steel and requires a coat of primer. Galvanneal, a basic steel
coated with an iron-zinc alloy, provides excellent rust protection when combined
with a coating of quality prime paint and is adequate for most interior and
exterior applications. And galvanized steel is basic steel treated with a
full zinc alloy and provides superior rust protection. Galvanized steel is
most commonly specified for exterior openings.
Where did the term "borrowed
light" come from?
This term originated from the concept of borrowing light from one room (such
as a corridor) to add light to another room (such as an office). A borrowed
light window frame consists of a fixed piece of glass.
Do I need to use intumescent
sealants for fire rated steel doors?
Generally speaking, no. These products are typically used for a smoke and
fire barrier on wood doors. Given the basic properties of steel (e.g. it expands
when exposed to heat), steel door manufacturers have not been forced to use
intumescents to obtain fire ratings.
What are the different
types of doors available from most manufacturers?
Steel doors are differentiated by their core, with each type of core having
a different set of properties and performance characteristics. The five most
common cores include kraft honeycomb, polystyrene, polyurethane, steel stiffened
and temperature rise. A honeycomb core door is a basic, general purpose door
used for interior openings with medium traffic. Styrene core doors are the
most commonly specified insulated core and are suitable for exterior applications
requiring an R factor (a measure of insulating performance) of 6.5. Urethane
core doors boast superior insulating properties (R factor of 11.1) and are
suitable for exterior openings in cold climates. Steel stiffened core doors
feature steel ribs in the interior of the door and are ideal for high traffic
situations where durability and security are important. And the specialty
temperature rise core doors are used when heat from one area to another (a
stairwell, for instance) must be retarded.
What is STC?
STC stands for "Sound Transmission Class", a measure of the extent to which
sound is prevented from being transferred from one area to another. The higher
the STC value, the less that sound can be transferred from one area to another.
The STC scale is a logarithmic progression, meaning that, for instance, a
jump of 3 points in an STC rating equates to a doubling in a door's ability
to prevent sound transmission. Sound retardant doors are tested as a unit
together comprised of the door, the frame, the hinges and the sound sealing
system. The following chart illustrates the sound retardant performance associated
with a range of STC values.
| STC Value |
Rating |
Description |
| 50-60 |
Excellent |
Loud sounds heard faintly or not at all |
| 40-50 |
Very Good |
Loud speech heard faintly, but not understood |
| 35-40 |
Good |
Loud speech heard but hardly intelligible |
| 30-35 |
Fair |
Loud speech understood fairly well |
| 25-30 |
Poor |
Normal speech understood easily and distinctly |
| 20-25 |
Very Poor |
Loud speech audible |
How does an acoustic (sound
control) door and frame assembly differ from standard hollow metal?
An acoustic unit is comprised of a door, door frame, perimeter and bottom
seals. The unit is tested in an independent laboratory. The door must be operable
and the test standard (ASTM E90-90, ASTM 413-87) compromises tests at 105
decibels over 18 distinct frequencies. Generally, NAAMM members who specialize
in this field can supply door leafs 1 3/4" (44 mm) thick and door frames to
suit standard acoustic wall constructions. Members meet stringent test standards
in a variety of proprietary ways.
Fire
Rated Doors and Frames FAQs
Why is only a 1.5 hour
rated door and frame required in a 2 hour rated wall?
Pierced walls (i.e. prepared to install door and frame) has a reduced fire
rating.
Are gaskets required on
fire doors?
Generally they are not, however, they may be required in smoke and draft control
areas if such a requirement is adopted by local authority having jurisdiction.
How can I label existing
doors and frames in the field?
Only by third party certification after field inspection. An inspector has
the right and authority to request that frames be broken out of walls or doors
and be cut open to expose their contents.
What are the basic hardware
requirements for fire door assemblies?
They must have a minimum of approved hinges, a listed and labeled self-latching
device and a labeled self closing device.
If hardware is labeled,
does it mean it can go on any labeled door?
No, labeled hardware cannot go on ANY labeled door. For instance, an opening
with VR x VR exit devices must use doors that were tested for this hardware
configuration. Therefore, even though the exit device is fire tested, it cannot
be used on doors that are designed for 8" Panic x VR.
Specifications
and Codes FAQs
Where can I get a specification
for a school building?
Please visit the Specification section of our
Web site where you will find different specifications for different building
types including schools (HMMA 861), jails (HMMA 863) and offices (HMMA 860),
among others.
What is the Dade County
Code?
The Dade Country Code is premised on construction specifications that are
able to withstand hurricane wind load on exterior doors, the impact of airborne
flying objects and water passage through door openings.
Will HMMA directory members
of the NAAMM meet Dade Country Codes?
Each member of the HMMA must do their own testing. While some HMMA members
have indeed tested their products under this code, we encourage you to visit
the Web site of each individual member for more information.
Do NAAMM products meet
all approved building codes?
Yes, NAAMM products meet the new UL10C UBC7-2 which is taking effect shortly.
Why should I use an HMMA
specification?
HMMA specifications are complete, tested, approved
and proven performers in the field.
HMMA/NAAMM
FAQs
How did the HMMA come into
being?
The HMMA was established in 1969 with the founding members coming from two
groups, namely the Southern Hollow Metal Manufacturers Association and the
Door and Buck Association, which had operated on the east coast of the United
States.
What is the relationship
between the HMMA and the NAAMM?
With more than 60 members from around North America, the HMMA is the largest
of four operating divisions of the National Association of Architectural Metal
Manufacturers (NAAMM), an organization traceable back to 1907.
NAAMM organizes its operating divisions along specific product
groupings. In addition to the hollow metal door concentration of the HMMA,
the NAAMM's operating divisions focus on stairs and railing systems, expanded
metal products, and metal bar grating, and collectively attract the support
of more than 1o0 organizations across North America.
What is the principal mandate
of the HMMA?
In short, the HMMA's principal mission is to serve the building construction
industry by creating the conditions essential for the production of high quality,
high performance hollow metal products. The HMMA achieves this mission by
developing, maintaining and distributing technical information on hollow metal
products, principally in the form of state-of-the-art technical specifications and detailed standards, in addition to periodic
technical reports and updates. The HMMA also serves the building construction
industry by involving itself in and communicating the results of the joint
testing of fire doors and frames.
What is the Hollow Metal
Manual?
The Hollow Metal Manual is a comprehensive collection of hollow metal guides
intended for specifiers, architects and end users. The Manual is comprised
of thirteen individual sections in a three-ring binder and provides authoritative
technical information regarding the manufacture, design, installation and
use of hollow metal doors and frames. The Manual includes hardware preparation
and location details, and the widely acclaimed manual on fire-rated doors
and frames.
In addition, the Manual also includes five guide specifications:
HMMA 860 for hollow metal doors & frames; HMMA 861 for commercial hollow metal
doors and frames; HMMA 862 covering commercial security applications; HMMA
863 to guide you in properly specifying detention security hollow metal doors
and frames, and HMMA 865 for sound control metal doors and frames.
How do I obtain a copy
of the Hollow Metal Manual?
To obtain your copy of the Hollow Metal Manual, please order
from the NAAMM site.
How can I find a name of
an HMMA member?
The fastest and easiest way to find one of HMMA's 60+ members is to go to
the Directory section of this Web site. At the
present time there is an alphabetical listing of all HMMA members. In the
very near future the page will allow users to search for members by region
and by area of speciality. Links to members with their own websites will also
be found in the Directory.
Are there any advantages
associated with purchasing hollow metal door and frame products from an HMMA
member?
Virtually every leader in the manufacture and distribution of hollow metal
door products is a member of the HMMA. Our members are united in their desire
to improve the quality and performance characteristics of hollow metal products,
as well as enhance the collective know-how and professional expertise of their
companies. You can thus be assured that an HMMA member is as committed to
the success of their firm and their industry as they are to the satisfaction
of designers, construction professionals and end-users everywhere.
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