Project Planning Frequently Asked Questions | Quality Glass Block and Window

FAQ

Q:

What kind of maintenance do my new Silver Line windows require?

A:

Silver Line vinyl windows are virtually maintenance free. They are unaffected by moisture, salt air, pollution and airborne chemicals. Vinyl will not pit, peel, flake or corrode making it unnecessary to paint. Cleaning is easy using a simple cloth and mild detergent. Do not use harsh detergents or solvents as these could damage the finish or appearance of the windows.

Q:

What is LoE² glass and how does it work?

A:

LoE² (low emissivity) glass provides year round comfort and energy savings. Two thin, transparent metallic coatings applied to the glass selectively filter solar radiation. During the summer, LoE² reduces heat gain, keeping your home cooler. LoE² glass helps keep you warmer in the winter by reflecting heat back into your home.

Q:

What is condensation and what causes it?

A:

Condensation is the result of excess humidity, or excess water vapor in the air coming into contact with a cooler surface such as a window causing visible droplets of water. To minimize this effect, Silver Line's windows are built with features to keep the surface of the glass warmer. When the humidity conditions are extremely high, use the following suggestions to help reduce the moisture in the air:

  • Open windows frequently to "air-out" your home.
  • Use a dehumidifier.
  • Use venting fans in the kitchen, bathroom and laundry room.
Q:

What is insulated glass and why does Silver Line use it in their windows and patio doors?

A:

Insulated glass consists of two pieces of glass sealed to a spacer. This creates an insulated air space between the two pieces of glass, resulting in better thermal performance. Insulated glass also reduces condensation while keeping the heat in during the winter and the heat out during the summer.

Q:

Are Silver Line windows flexible with sizes to fit certain openings?

A:

Very much so. There are many sizes and shapes to choose from and special orders are available when needed.

Q:

What is ENERGY STAR and how does a window company qualify for ENERGY STAR compliance?

A:

ENERGY STAR was started by The United States Department of Energy. ENERGY STAR helps businesses and consumers become aware of what products save energy to save money while protecting the environment for future generations. When a product, such as a Silver Line window, meets the requirements for ENERGY STAR that product then qualifies for the program.

Q:

How can I determine the energy efficiency and durability of Silver Line Windows or any other window?

A:

Two organizations, the American Architectural Manufacturing Association (AAMA) and the National Fenestration Rating Council (NFRC), test the performance and quality standards for windows.

The NFRC established standards for thermal performance.

Q:

How can I determine the energy efficiency and durability of Silver Line Windows or any other window?

A:

Two organizations, the American Architectural Manufacturing Association (AAMA) and the National Fenestration Rating Council (NFRC), test the performance and quality standards for windows.

The NFRC established standards for thermal performance.

U-factor: This is a measure of heat loss. The lower the U-factor the better.

SHGC (Solar Heat Gain Coefficient): Once again the lower the better.

VT (Visible Transmittance): The higher the visible transmittance, the more daylight is transmitted. A high VT is desirable to maximize the amount of daylight entering the home.

The AAMA established standards for structural integrity, air infiltration, water infiltration resistance and forced entry resistance.

Structural Integrity is the ability to withstand wind and other dynamic pressures. This is rated in design pressure (DP). The higher a product's rating design pressure, the greater the amount of wind or pressure the window will withstand.

Air Infiltration tests involve the equivalent of 25 mph wind. The lower the air infiltration rating the better.

Water Infiltration tests a window's ability to resist water leakage through the window frame, sashes, joints, weather-stripping, etc. No leakage is permitted under this test criteria.

Forced entry is tested by a certified lab technician using many different tools to simulate breaking into a home through the window. Next, windows and doors are subjected to hundreds of pounds of force to try to lift or push them open while in the locked position.

Q:

What are R-values and U-values?

A:

The R-value is the resistance a material has to the flow of heat (the higher the R-value, the greater the resistance).

The U-value is the amount of heat that is transferred through a material. (the lower the U-value, the better insulating quality).

Q:

Why should I replace my existing windows?

A:

Silver Line windows offers many styles to give your home a beautiful new look while improving energy efficiency. They can add value to your home while cutting down your heating and cooling bills.

Q:

How do vinyl windows compare with windows made from other materials, such as wood and aluminum?

A:

Vinyl windows compare very favorably to those made of other building materials. Vinyl allows for smooth operation year round because of its self lubricating properties and the fact that it does not shrink, swell or bend during harsh weather conditions. The combination of aesthetic appeal, energy efficiency, and low maintenance provides equal or better performance and is often more economical.

Q:

Are there specific details for installing fire rated glass block window assemblies?

A:

The framing, anchoring and installation details are the same as installing any non-fire rated glass block panel and as shown in our published literature. The one distinct difference is that the sealant used at the jamb and head locations must be a fire retardant type sealant.

Also all 90 minute rated glass back window assemblies may only be installed within masonry or concrete walls, may only be framed and anchored with 1/4 inch thick steel channels or angles that form channels; and the expansion material within the channels must be doubled (or 3/4 inches thick).

Finally our Universal Mortar Spacers are listed by Underwriters Laboratories under Classification Number R 18572 and can be used to construct fire rated glass block window assemblies.

Q:

What are the fire ratings of Pittsburgh Corning Glass Block products?

A:

With the exception of all 12 inch by 12 inch sizes, finishing units, corner blocks and the DELPHI® pattern block, all glass block sizes 8 inches by 8 inches or less in size have at least a 45 minute fire rating when used as a window assembly within a one hour rated masonry or non-masonry studded walls.

All THICKSET® 90 (thick-faced) and solid glass blocks have fire ratings of up to 90 minutes, and the THICKSET® 60 glass blocks have fire ratings up to 60 minutes, when used as window assemblies and when permitted by code.

All of our fire rated glass block products along with maximum sizes and dimensions are listed in Underwriters Laboratories’ current issue of Fire Resistance Directory - Volume 3 under our classification number R 2556. A listing of our products can also be viewed on Underwriters Laboratories’ Website.

Q:

Is the Walk-In Shower Kit available with a "left" entry?

A:

Yes.

Q:

What is special about the bases?

A:

They are specially designed to accommodate glass block through molded channels that serve as guides for block placement. Also, they are constructed to support the extra weight of glass block walls.

Q:

What are the bases made of?

A:

They are made of Lucite® XL cast acrylic. This high quality material resists chipping and peeling. In the rare event the material scratches, polishing will restore it back to the original shine. Color goes all the way through the material.

Q:

Are the bases and shower components code approved?

A:

The NAHB Research Center has certified the bases to meet Z124.2. Glass block installed with mortar is exempt from the safety glazing requirements of all model building codes.

Q:

Does Pittsburgh Corning offer a warranty on the Shower System?

A:

Yes, as follows:

Block and Doors - 5 year limited warranty

Shower Bases - 3 year limited warranty

Q:

Can shower bases and doors be purchased separately?

A:

Yes, but there is no true advantage in doing so. Contact Pittsburgh Corning Customer Service for prices if required.

Q:

What materials other than what come in the kit are required for installation?

A:

Glass block mortar, plumbing fixtures, and ceramic tile (or tile board) for rear walls need to be purchased separately.

Q:

Are kits available with different installation options?

A:

Yes. You can choose between traditional Mortar Installation or the new ProVantage® Glass Block Installation System – an easy to use mortar-less method using a spacer system, sealant and grout.

Q:

Are kits available in different glass block patterns?

A:

Yes. Kits are available in either the Decora® or IceScapes® patterns.

Q:

Can I get ARQUE, TRIDRON or HEDRON block with a finished bull nose end?

A:

Currently, these blocks are not available in a bull nose end.

Q:

What size end-block finishing units are available?

A:

End-block finishing units are available in 6x8x4 and 8x8x4 inch sizes. Thinline End-block units are available in 4x8x3 inch size.

Q:

What other physical properties do glass blocks have?

A:

The insulation or R value of the Premiere Series (3 7/8 inch thick) glass block when installed with mortar is 1.96. The reciprocal U value is .51. The R value of our Thinline series (3 1/8 inch thick) glass block when installed with mortar is 1.75, the reciprocal U value is .57.

Q:

What are the dimensions of glass block?

A:

All face dimensions of hollow glass block are 1/4 inch less than nominal size. In other words, 8 inch by 8 inch block is actually 7 3/4 inches square. Typically a 1/4 inch mortar joint is used so that the center line of joint to the center line of joint is a full 8 inches or 6 inches or 12 inches depending on the nominal size of the block used.

Q:

How tight of a radius can I make with glass block?

A:

Minimum recommended radii are dependent on the size of glass block to be used. The tightest radius recommended, measured to the interior face of the wall is 32 inches using the 4 inch by 8 inch glass block units with the 8 inch side oriented vertically. The other minimum radii recommended are 48 1/2 inches when using the 6 inch by 6 inch block, 65 inches when using the 8 inch by 8 inch block, and 98 ½ inches when using the 12 inch by 12 inch block. In all cases this will result in a 1/8 inch thick vertical mortar joint on the interior side of the wall and 5/8 inch thick vertical mortar joint on the exterior side of the wall.

For a tighter radius, our ARQUE® glass block which is a curved face block with tapered sides will achieve a 12 inch radius to the interior face and a 16 inch radius to the exterior face. By alternating other sizes of glass block in between ARQUE® glass block units, interior radii of 20 to 30 inches can be achieved.

Q:

How large of a glass block panel can I design?

A:

Assuming a normal design wind load of 20 PSF (about 88 mph wind) and based on using our Premiere series (3 and 7/8 inch thick) glass block products, the maximum exterior size panel should not be larger than 144 square feet with limiting dimensions of either 20 feet in height or 25 feet in length - without exceeding the maximum area of 144 square feet per panel. There is a 2.7 safety factor incorporated within this criteria.

 For areas of glass block larger than 144 square feet, the use of structural columns and/or shelf angles must be used to sub-divide these areas. For long horizontal expanses, structural columns or mullions (stiffeners) must be used. For vertically high expanses of glass block, the use of horizontal supporting shelf angles must be used to maintain the maximum area recommended and to stay within the dimension limitations stated above.

The maximum area of interior panels should not be greater than 250 square feet with similar limiting dimensions per panel of either 20 feet in height or 25 feet in length.

Q:

What are the basic design criteria for using glass block?

A:

Glass block must be used as a non-load bearing material. All construction above glass block panels must be independently supported. Individual glass block panels must be isolated within their openings with expansion strip material at head and jamb locations with no loads imposed on the glass black panel. Glass block panels are mortared at the sill. Sills should be coated with a water based asphalt emulsion prior to laying the first course of glass block.

Installed weights of glass block walls are 20 pounds per square foot of wall area for Premiere Series blocks; 25 pounds per square foot for Thickset 60 Series block; 30 pounds per square foot for Thickset 90 Series (thick-faced) block; and 40 pounds per square foot for VISTABRIK® and solid glass block units. All structural members supporting glass block construction must be designed and sized for maximum deflection of L/600.

For exterior applications the building codes allow the use of types N or S mortar utilizing Portland cement, and sand that complies to ASTM(C)-144. The use of accelerators and/or acid washing is not recommended. Nine gauge ladder type reinforcing is to be used in horizontal joints with maximum spacing of 16 inches on center.

Glass block panels are to be framed and anchored at head and jamb locations with either a channel type restraint or with PC panel anchors that give the wall a much cleaner look. Panel anchors are spaced at no more than 16 inches on center up both jambs and across the head.