Seattle Sun's commercial glazing system
sets us apart from other sunroom manufacturers.
Seattle Sun uses a commercial glazing system. A commercial glazing
system consists of specific types of insulating glass, sealants
and an aluminum support and capping system that is installed in
a manner prescribed by industry standards. It is the same type
of system used in skyscrapers.
Many solarium companies use systems similar to carpenter site-built
structures to keep costs down. They use materials that can be
bought "off-the-shelf" at your local lumber store.
Commercial glass contractors don't use these "off the shelf"
components because of maintenance problems and a short life
expectancy.
The technique used to set the overhead glass in your sunroom
affects:
Whether the sunroom is water tight or leaks.
Whether the wood in the sunroom remains dry or begins to decay
and develops dry-rot.
Whether the insulating glass maintains its seal integrity or
'fails' and fogs up.
A commercial glazing system includes all of the following:
The overhead glass in encased in an engineered aluminum system.
Specific installation techniques and sealants are used to meet
industry standards.
The lower edge of the glass unit must be supported by a vertical
aluminum stop so that both pieces of glass are equally supported,
preventing the separation of the two pieces of glass.
The dead air space of the insulating glass unit must be sealed
from outside air with a silicone dual seal unit. This sealant
does not degrade with UV and the structural silicone holds the
two pieces of glass permanently together, preventing seal failure.
The insulating glass unit must be elevated above the gutter
so that the edges can not come in contact with water. Water
contact will degrade the seal and cause it to fail.
The primary seal against rain must have an internal back-up
gutter to protect against severe weather conditions. If water
does get past the rain seal, it is trapped in the gutter and
is prevented from entering the interior of the room or contacting
wood components. The gutter lets the water drain to the outside
through a weep hole.
A commercial glazing system's glass, sealants and aluminum parts
thermally expand and contract together in a fashion that is
compatible with maintaining both the dead air glass seals and
primary rain seals.
No horizontal caps are used, preventing water, leaf and dirt
build-up on the glass.
Glazing systems that are site-built by carpenters are problematic
for the following reasons:
1. The glass adheres directly to the wood rafters with a double
stick tape.
2. Without a backup gutter, the primary rain seal is relied
upon totally for preventing leakage.
3. If the primary rain seal fails, water can rest against the
dead air sealants of the glass unit, eventually causing seal
failure.
4. Once inside and in contact with the wood, water can seep
to the far reaches of the sunroom, showing up in unexpected
places and making detection of the leak point difficult. Water
trapped on wood parts can cause permanent water stains, decay
and dry-rot.
5. Polysulfide, butyl and polyurethane sealants used by residential
insulating glass manufacturers to maintain a dead air space
are not intended for overhead glass installations and have a
tested life expectancy of 6-8 years. The dual seal silicon units
that Seattle Sun uses have a tested life expectancy of 40 years.
6. Overhead insulating glass compressed between wood on one
side and aluminum on the other, and which is not properly supported,
is subject to tremendous stresses as these three materials expand
and contract differently during temperature changes. This movement
will eventually cause the seal to fail.
7. Horizontal caps trap unsightly dirt, leaves and debris, and
also block the flow of water - causing standing water at the
caps and leaks into the room.
Seattle Sun Overhead Glazing System:
Aluminum tubular system is watertight and not dependent on sealants.
Site Built Glazing:
Glass on wood is dependent upon sealants like heat seal tape that
can lose adhesion and cause leaks.
Structural Silicone Dual Seal Insulating Glass Units
An insulating glass unit (I.G. Unit) is composed of two pieces
of glass sealed together with a dead air or Argon gas filled space
between them. It is essential that the "dead" air space
remain isolated from the outside air. The dead air or Argon has
had the moisture removed from it. Moist, outside air would cause
condensation and fogging on the interior surfaces of the I.G.
unit. It also compromises the insulating ability of the unit.
Over the past 30 years, a dozen different rubber
systems have been tried with varying rates of success. Designers
and contractors who specialize in large, commercial buildings
specify only structural silicone dual seal units. Structural silicone
firmly holds the two pieces of glass together while a second component
- Polyisobutylene (PIB) - provides an excellent vapor barrier
keeping moist air out of the unit. Both of these rubber compounds,
after rigorous testing have been proven to have excellent resistance
to ultraviolet degradation, one of the chief causes of seal failure.
The sealants were evaluated by an independent certified
testing lab using a controlled "torture chamber" for
impartial comparison. One week in the controlled environment equals
approximately one year in a your sunroom.
The following results were submitted by J.A. Box
of Tremco in his paper presented at the 1992 Insulating Glass
Manufacturers Association Conference.
TABLE II
Relative I.G. Seal Durability*
| EDGE SEAL |
LONGEVITY |
| Single Seal: Polysulfide or Polyurethane |
6-8 weeks |
| Dual Seal: PIB/Polysulfide or PIB/Polyurethane |
11-15 weeks |
| Dual Seal: PIB/Silicone |
40+ weeks |
*Note: Aged with P-1 Pre-conditioning Chamber -
140 degree F, water spray, UV radiation.
The dual seal silicone units lasted up to 5 times
longer than the other units! This is why Seattle Sun uses only
dual seal silicone units...to ensure you get a lifetime of trouble
free enjoyment from your sunroom addition.
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