Frequently Asked Questions (FAQs)

If you have a question about a Pittsburgh Corning product, you just might find your answer right here. To view a list of questions and answers, please choose a topic below. Or click here for MSRP prices on the most popular Pittsburgh Corning Products.

ProVantage®

Please choose a question:

Can I use any tile grout with the system?
No. You must use ProVantage® Glass Block Surface Grout, which has been specially formulated for use with the ProVantage® Glass Block Installation.
Can I use any silicone sealant with the ProVantage® spacers?
No. Pittsburgh Corning Glass Block Sealant has been specially formulated for use with the ProVantage® Glass Block Installation System — it has the necessary tooling time and is compatible with both vinyl and glass.
How large of a panel can I build with the ProVantage® Glass Block Installation System?
Interior panels must be no larger than 85 sq. ft. and framed on at least two sides. Exterior panels must be no larger than 50 sq. ft. and framed on all four sides.
Can I build the panel and grout the joints in the same day?
No. The sealant must cure overnight before applying the grout.
Can I use either sealant or tile grout to finish the joints of my glass block panel?
Glass block panels that are built using the ProVantage® Installation System and have at least 3-sided support can be completed by finishing the joints with either sealant or surface grout. Sealant finishing is not recommended for wet environments. Glass block panels that have less than 3-sided support should be completed by finishing the joints with surface grout only.
Can I install Pittsburgh Corning Thinline Series using the ProVantage® Glass Block Installation System?
No. The ProVantage® Glass Block Installation System is designed for use with only Pittsburgh Corning Premiere Series (4" thick) glass block.
Where can I buy the ProVantage® Glass Block Installation System?
At any Pittsburgh Corning Glass Block distributor and Home Center.
What is the per-square-foot cost of a glass block installation using the ProVantage® Glass Block Installation System?
Material costs to build a 40" x 40" straight glass block wall are approximately $20 per square foot. This includes the block, sealant, grout and all of the necessary ProVantage® components.
How long will it take to install a glass block panel using the ProVantage® Glass Block Installation System?
For most size panels, you will need one day to install the glass blocks with the spacers and sealant and one day to grout the joints.
Can glass block other than Pittsburgh Corning Glass Block be used with the ProVantage® system?
The ProVantage® system was designed and tested exclusively for use with Pittsburgh Corning Glass Block. Dimensional characteristics and product composition of other glass blocks may prove incompatible with the ProVantage® Glass Block Installation System.
The vertical spacers are precut for 8"-high block. What do I use for other block heights of 6" or 12"?
Vertical spacers for other than 8"-high block can be created by straight-cutting a piece of spacer to fit the corresponding height of the glass block.
What is the thickness of the grout joint?
By sponging the grout joints at the recommended 45 degrees to the joints, they will appear to be one-quarter of an inch. Sponging parallel to the joints will remove some of the grout, and the joints will appear narrower.
Where can I find installation instructions for the ProVantage® Glass Block Installation System?
Installation instructions can be found in each package of ProVantage® Vertical Spacers and on the Pittsburgh Corning website at www.pittsburghcorning.com.
Can the ProVantage® system be used for commercial applications?
Yes, if installed in accordance with the size restrictions.
Can I use colored grout finish with the ProVantage® Glass Block Installation System?
Only the ProVantage® Glass Block Grout is recommended for use with the ProVantage® system. It is currently available in white.

Fire Rating

Please choose a question:

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

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.

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

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.

Click here for Glass Block plastic spacer results.

Designing with Glass Block

Please choose a question:

What are the basic design criteria for using glass block?

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.

How large of a glass block panel can I design?

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.

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

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.

Physical Properties

Please choose a question:

What are the dimensions of glass block?
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.
What other physical properties do glass blocks have?

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.

The visible light transmission of all hollow glass block products can be found here.

The STC, or Sound Transmission Class, of the Premiere Series glass block products range between STC values of 35 to 40 depending on the size of glass block. The STC value for the THICKSET® 60 Series block is 48, the STC value for the THICKSET® 90 Series block is 50, and the STC value for solid VISTABRIK® units is 53.

What size end-block finishing units are available?
End-block finishing units are available in 6x8x4 and 8x8x4 inch sizes. Thinline End-block units are available in 4x8x3 inch size.
Can I get ARQUE, TRIDRON or HEDRON block with a finished bull nose end?
Currently, these blocks are not available in a bull nose end.

LightWise® Windows

Please choose a question about either LightWise® Aluminum Clad Wood Windows or LightWise® Vinyl Windows:

LightWise® Aluminum Clad Wood Windows

Can you replace an individual glass block?
Yes, Pittsburgh Corning Corporation offers a free LightWise® window repair kit by calling the Customer Support Department at 800-545-5001.
What are the physical properties of the LightWise® Aluminum Clad Wood Window?
Installed weight 16 lbs. square foot
Light Transmission 75%
Sound Transmission STC = 31
Can custom colors be ordered?
Yes, provide us with a color chip and we will try to match.
What is the jamb width for the LightWise® Aluminum Clad Wood Window?
4-9/16 inch. For large jamb width a 2inch extension jamb is available as an accessory and can be trimmed to fit.
Do LightWise® Aluminum Clad Wood windows have a warranty?
The glass block panel assembly and window frame are covered by a ten (10) year limited warranty. Included in the warranty are manufacturing defects, frame chipping, cracking, peeling, pitting, and blistering. The window panel is warranted against leaks, discoloration, and separation.

LightWise® Vinyl Windows

What accessories are available and how do I get them?
Pittsburgh Corning Corporation offer a J channel, brick mold and mullion accessories. These are available by calling the Customer Support Department at 800-545-5001.
Can you replace an individual glass block?
Yes, Pittsburgh Corning Corporation offers a free LightWise® window repair kit by calling the Customer Support Department at 800-545-5001.
Can I install a series of LightWise® Vinyl windows in an existing frame?
Yes, remove the adjacent nailing fins (using a utility knife) of the two LightWise® windows and install the mullion cap design to cover the seam.
What is the R-value for the LightWise® Vinyl windows?
LightWise® Vinyl windows have an R-value of 2.17 which equates to a double pane window.
What are some other physical properties of the LightWise® Vinyl Window?
Installed weight 11.25 lbs. square foot
Light Transmission 75%
Sound Transmission STC = 31
Do LightWise® Vinyl windows have a warranty?
The glass block panel assembly and window frame are covered by a ten (10) year limited warranty. Included in the warranty are manufacturing defects, frame chipping, cracking, peeling, pitting, and blistering. The window panel is warranted against leaks, discoloration, and separation.

Shower Systems

Please choose a question:

Are kits available in different glass block patterns?
Yes. Kits are available in either the Decora® or IceScapes® patterns.
Are kits available with different installation options?
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.
What materials other than what come in the kit are required for installation?
Glass block mortar, plumbing fixtures, and ceramic tile (or tile board) for rear walls need to be purchased separately.
Can shower bases and doors be purchased separately?
Yes, but there is no true advantage in doing so. Contact Pittsburgh Corning Customer Service for prices if required.
Does Pittsburgh Corning offer a warranty on the Shower System?

Yes, as follows:

  • Block and Doors - 5 year limited warranty
  • Shower Bases - 3 year limited warranty
Are the bases and shower components code approved?
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.
What are the bases made of?
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.
What is special about the bases?
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.
Is the Walk-In Shower Kit available with a "left" entry?
Yes.