It used to be simple to choose between
a curtain wall and storefront glazing system.
Curtain walls were for large, towering buildings.
Storefront systems were for small, one-or-two-story
buildings, often retail stores.
The name said it all.
Today, things are a bit more confusing.
There are more storefront systems and more
curtain wall systems. Many two-story buildings
combine uses, such as office/retail. As
you look through brochures and CDs, you
see center-set applications, front-set applications,
structurally silicone products, tubular
and I-beam curtain walls-and you wonder
which of these many products will fit your
project application.
To make matters more difficult, those towering
buildings are not as common now. Most have
been replaced by buildings no more than
10-stories tall. So the natural question
is, "Can't I use a storefront system
on this six-story office building?"
CDC consultant Jerry Johnson says the answer
is not a simple one, but the following rule
of thumb can make it a pretty basic decision:
"Storefront systems were designed primarily
for use in one-to-four-story applications-usually
small retail buildings or strip centers."
Other factors to keep in mind are the following
differences between the two systems:
|
Storefront |
Curtain
Wall |
Finish |
One
Finish |
Dual
Finish |
Gasket |
Vinyl |
EPDM,
Silicone |
Performance
Air |
6.24
=.06 CFM/FT² |
6.24
= .06 CFM/FT² |
Water
Test |
10
psf per ASTM E 331 |
15
psf per ASTM 331 |
|
The key factor in selecting a curtain wall
or storefront system is the enclosure's
ability to handle and control water. Water
control is the ability of the glazing system
to collect and drain to the exterior of
the building. As you can see by the storefront
and curtain wall detail illustrations, a
storefront system has a very limited water
head compared to a curtain wall system,
but a storefront system will perform very
well in the proper application.
Water control is a much bigger problem
for specification writers than concerns
about structural requirements, says Johnson.
"It is usually obvious when a storefront
glazing system is not capable of meeting
structural and wind load requirements. When
a system fails, water control is usually
the problem."
The following checklist of questions about
the project requirements and system capabilities
may help make the selection easier:
- What do the specifications require
• CRF and "U" value ratings?
- Air, water and structural requirements?
• Specified gaskets?
- Finish requirements? • Live-load
slab deflections and seismic?
Cutting corners is not recommended when
it comes to overall building construction,
and the glazing system is no different.
A building owner might get by using a storefront
system when a curtain wall system is needed.
However, that decision might prove costly
in the long run. That is why it is important
to determine the exact requirements of a
glazing system before making your selection.
|