The days of single glazed windows and doors are probably over or at least limited for exterior products. However, the days of the more complex glass makeup's offer a palette of choices for today's functional building envelope. A variety of glass types can be combined in an insulated glass unit for thermal reduction, as well as, tint controls, UV blocking and sound inhibition. These variations are needed to help adapt to the requirements of modern architecture. Along with meeting the code requirements, modern glass systems offer options that can enhance the user experience and add to the aesthetics of the architectural design.

It is important to note that one of the major elements to consider in the design of the windows and doors for a project is the glass and the sizes that are locally available. This is a cost and design consideration. Oversize glass can dramatically affect the overall cost and the warranty of the fenestration on a project. On jobs that we are able to supply the glass for, the maximum glass size that can be warranted is 60 sq. ft. The maximum length in one dimension is 78" and the maximum in the other direction is 144. The total then should not exceed 60 sq. ft. Many vendors limit the warranty to 50 sq. ft. so it is recommended that this is qualified as a part of the design process. When larger glass is needed for a project, there are sources that supply oversized glass. Each company will have their preferred glass coatings and these will also need consideration for color and transparency as well as matching the normal glass on a project. Scroll down this page for additional information on oversized glass..  

Insulated Glass

 

 

The makeup of an insulated glass unit typically consists of one pane of glass on the interior and one pane of glass on the exterior. These are separated by a "spacer bar" and this assembly is adhered together and then back filled with water resistant sealants. More extreme make ups can include triple pane glazing, suspended center films as well as argon and krypton gas filling of the air gap between glass panes.

For NFRC rated fenestration, the glass fabricator must also test and certify their insulated products.



Glass Effeciency

The bottom line, in the science of glazing and thermal transfer, is the effect of the trapped air in the space between the glass. The glass itself has very poor thermal resistance, so the air space is the primary resistance. Testing has shown that the optimum space for air and argon is around 1/2" up to 5/8" between glass panes. Less space increases thermal transfer because it has less resistance and more air space allows for turbulent mixing of the air which actually increases thermal transfer. Argon gas improves performance when used in the 1/2" air space whereas krypton gas improves performance when the design forces the use an air space below 7/16."

Today's spacer bar has also been upgraded from a folded aluminum shape to a combination of different thermally resistant materials. These materials include metal, foams and plastics. Use of the thermal spacer bars improve the overall efficiency of the insulated glass unit.



Glass Coatings

Along with the science of the air space transfer, different coatings on the glass can have an impact on thermal transfer. Low E glass types can be oriented to reflect heat away from the building or reflect heat back into the living space depending on the environmental need. Laminated glass can inhibit sound and the PVB layer between the glass will block out a high percentage of UV rays. Tinted glass can be used in a variety of shades that can vary the SHGC (solar heat gain coefficient).



Glass Installation

With Jada products, the installation of the glass is from the inside of the house. This method best protects the exposure of the insulated glass edge, glass clips and beauty rings from moisture. Insulated glass needs to remain dry and ventilated to maintain the warranty.

From the exterior, the bond between the glass and the metal sash is protected with a "wet seal" of Dow Corning 795 sealant. This is carefully tooled in for a smooth transition between glass and steel as well as a durable and flexible water seal. The glass is held firmly in the sash with concealed glass clips and then the entire perimeter of the glass is fit with a "beauty ring" that conceals the clips.

In unique circumstances for oversized glass, the glass is installed from the exterior. This allows for the crane lifting and install of the oversized glass without moving the glass through the building. When using this method the frame profiles are made up using stainless steel materials to increase the rust resistance for the weather side beauty ring and glass clips.

For long term maintenance or glass replacement the beauty rings can be removed and the glass clips screws removed. Then new glass can be installed and the clip and beauty ring system can be re installed.

Oversized Glass

The larger the glass the more difficult to produce perfect glass. Agnora glass can produce tempered insulated glass in very large sizes up to 130 x 300. Careful consideration is needed to evaluate the implementation of oversized glass. For fixed openings, it is really a question of overall glass thickness, weight and installation access. For operable openings the weight and thickness are more of an issue. Overall thickness may limit the systems that the glass can fit into, while the weight can limit the functionality of the product.

The coatings for oversize glass are not a plentiful as normal glass makeups. The glass coatings can affect thermal qualities and overall product values as well as color of glass when matching with other glass types.

Most oversize glass is sold without warranty. Selecting the right vendor should include a clear understanding of their warranty and their standard for imperfection of the glass.



Glass Inspection Guidelines

Through our experience with many glass vendors we have come to say that “perfect glass is 80% perfect”. This seems to be the reality of the glass industry. When people look through glass at the world outside, all glass will look good. It is when people look “at” the glass that the questions arise. Viewed from a close distance with bright lights on, one can find flaws in every piece of glass. For this reason the glass industry has established standards of glass inspection.

The industry standard for glass inspection is called the 11 foot rule. It basically says that it considers imperfections as something than can be seen under normal lighting from 11 feet away, and that it is in the center 80% of the glass.  

When we supply the glass we strive to improve upon this standard and provide glass that is generally clear without workmanship flaws. We work closely with our manufactures starting with the understanding that our clients need a higher quality product. In the end, with some rejections and some remakes, we get “pretty good” glass. Given enough remakes, one could probably get “better than standard” glass.  In the event that glass needs to be replaced after it is established to be "within the inspection standards", we can keep trying until everyone is satisfied and just track the costs for the effort as an added budget item for the project.

There are ASTM inspection standards that can be introduced to better clarify the inspection methods, but in the end it is good to get 80% perfect glass.

One other thing to be aware of is that the use of “rare” specialty glass can add to the challenge of getting “perfect” glass. Specialty glass can lead to working with shops that take even less care in the cleaning and insulating process.. With every glass type consideration there should be a study of the actual supplier and their quality measures.



inspection methods

All inspections are done with the viewing angle at 90 degrees to the glass surface, 

uniform diffused lighting that stimulates daylight, and with the inspector looking thru rather than at the glass surface.

These guidelines include architectural glass that is produced as annealed, tempered, insulated, or laminated.


Scratches and Rubs

The inspector begins the inspection by standing at a distance of 160” from the glass surface.  The inspector then moves closer to the glass surface, stopping at the point where the scratch or rub is first detected.  If this distance is between 160” and 132” then it is cause for rejection.  If the scratch or rub is visible when viewed between 132” and 40” and is over 3” long it is cause for rejection.  If the scratch or rub is visible when viewed between 132” and 40” and it is less than 3” long, it is allowed as long as it is separated from a similar scratch or rub by at least 24”.  If you need to be closer than 40” from the glass surface to view the scratch or rub, then it is allowed.

 

Bubbles, Pits, Knots, and Dirt

With the inspector standing at 39” from the glass surface, and the glass thickness is ¼” or less, bubbles, pits, knots, or dirt is allowed if the average of blemish’s length and width is 1/16” or less.  Blemishes with an average length and width of 3/32” are allowed if they are separated from a similar blemish by at least 24”. Bubbles, pits, knots and dirt is not allowed if their average length and width exceeds 3/32.”

 

Edge Chips

DEPTH- measuring from the face of the glass a chip is allowed if it’s depth does not exceed more than 50% of the glass thickness

WIDTH- measuring the perpendicular distance from the edge of the glass to the inner edge of the chip, a chip is allowed up to half of the glass thickness or ¼”, whichever is greater; for mirrors up to half of the mirror thickness or 1/16”, whichever is greater.

LENGTH- measuring parallel from the edge of the glass to the edge of a chip, a chip is allowed if its length does not exceed two times its width.

Soft Coat or Hard Coat Low-E Coatings

Coating Pinholes

Coating pinholes greater than 1/16” of an inch are not allowed.  Pinholes less than 1/16” in diameter are allowed if they are located outside of the central viewing area. At a distance of 120” from the glass surface, three or more pinholes greater than 3/64” in size are not allowed if they are located within a 6” diameter cluster of one another.

 

Coloration

Low-e coated glass may exhibit a hue or coloration that is not apparent in architectural samples, especially in shaded or darkened light or when viewed at a glancing angle.  This coloration is inherent to the coating process and is not a reason for rejection.

 

Heat Treated Glass

The factors inherent in the heat treating process may change the surface of the treated glass and result in a distortion of reflected objects when viewed on the glass surface.  The ability of the viewer to see this distortion is dependent on the size and shape of the glass, the location that the glass is glazed on the building, and the distance the viewer stands from the glass surface.   Reflective coated glass as well as the expansion and contraction of the air space between the glass surfaces of an insulated unit can also enhance this distortion.  These are not considered defects and are not cause for rejection

 

Glazing Links

Glass Manufacturers   PPG Glass  -  Cardinal Glass  - Saint-Gobain 

Glass Insulator  Thermal Sun  -  Agnora Glass 

California WUI ( wildland urban interface )  Cal Fire  -  Fire Code  -  City LIst Glass (see pg 14-708A.2.1)  -  State WUI Map  -


Great WUI article: http://windowanddoor.com/article/junejuly-2016/fire-season

Glass Information

Glass Thickness Per Product

Out-Swing Products 11/16" to 1 1/8"

Sliding and Folding Products 7/8" to 1 3/8"

In-Swing Products 7/8" to 1 3/8"

EBE 65 "Full" Profiles 3/4" to 1 3/16"

EBE 85 "Full" Profiles 1 1/8" to 1 13/16"



Typical Glass Sizes Available

PPG Tempered Soft Coat Low-E 83" x 142"

Cardinal Tempered Soft Coat 96" x 130"

Max Tempered Hard Coat Low-E 96" x 130"

Standard Warranty: Under 60 sq ft - 10 yr



Specialty Glass Sizes Available

Max Hard Coat Low-E 120" x 170"

Max Insulated 130" x 240"

Laminated Glass 130" x 275"

Max Schott Amiran 69" x 148"

Max PPG Opti-View 96" x 130" +

Max Sage Tint Glass 60" x 120"

Max Switch Lite Glass 38" x 114 +

Standard Oversize Warranty: 5 yr.

Oversize See: www.agnora.com



Curved Glass Info

Max Size: 66"w x 126" h

Hard Coat Low-E Available

Laminated and Insulated Available

Standard Warranty: 5 yr.

see: www.e-bentglass.com

Weights

Glass Weights

1/8" = 1.6 lbs -- 3/16" = 2.4 lbs

1/4" = 3.2 lbs -- 5/16" = 4.0 lbs

3/8" = 4.9 lbs -- 7/16" = 5.6 lbs

1/2" = 6.4 lbs -- 9/16" = 7.2 lbs

5/8" = 8.2 lbs -- 11/16" = 8.9 lbs

3/4" = 9.7 lbs -- 13/16" = 10.5 lbs

7/8" = 11.3 lbs -- 1" = 12.9 lbs



Secco Profile Weights

Avg. TDL = 1.8 # lf

Avg. Narrow Profile = 2.1 # lf

Avg Wide Profile = 3.8 # lf

Heavy Duty Wide Profile = 4.1 # lf

Sliding Screen Profile = 1.4 # lf

Screen TDL Profile = 1.1 # lf

Top Hung Track Profile = 1.2 # lf



Narrow Profile Sash Weights

TDL w/ 1/8 Over 1/8 = 6.3 # sf

1 Lite w/ 1/4 Over 1/4 = 8.9 # sf

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