Subway Glass Tile Installation Guide

The Skinny of Properly Installing 3X6 Glass Subway Tile

For installing 3X6 subway glass tile, we recommend using a white thin-set mortar with a flexible acrylic additive. Apply this mixture with the manufacturer’s recommendations of notch trowel. Spread only enough adhesive as will be covered with the tile within 15 minutes. Back-butter each piece of tile with the flat edge of the trowel. Be sure to achieve full coverage on the back of the tile in order to avoid the notch marks in the thin set from showing through the glass. Carefully, press the glass into the thin set mixture leaving even spacing between tiles. For a more contemporary look we recommend using 1/16" spacers to ensure even spacing. If you prefer a more traditional look the a 1/8" spacer is recommended. Allow for movement joints where the tile abuts restraining surfaces and around the perimeter of the installation. Grout with an unsanded grout, to prevent scratching, after the adhesive has had proper time to cure according to the manufacturer’s recommendations.


A ceramic tile cutter is not recommended. We recommend using a wet saw with a diamond blade ( PREFERABLY NEW) designed for cutting glass tile. A porcelain continuous blade is best suited for cutting glass, and is available in multiple sizes. Whenever possible, cut edges should be placed in corners where they can be hidden. A simple trick to help cut our 3X6 glass subway tiles is to reduce the blade height to just 50% of the thickness of the tile. The place the tile with the white backing facing up and score the top half of the glass. Next, increase the height of the saw blade and flip the tile over so the backing is now on the bottom. Run the tile thru the saw again and you should get a clean cut. This two phase approach help reduce the load on the blade when cutting the back and will help to not tear or shatter the backing emulsion from the back of the tile.

To dress (smooth) the cut edges of the glass tile use a #120 lapidary (tile rub stone) or 220 thru 600 grit PVA polishing pads available from Alpha Professional Tools or MK Diamond. Do not contact the face of the tile during dressing as this will damage the tile surface.


We recommend using a drill bit that is especially designed for glass. The glass tile must be securely champed into place to prevent movement of the tile during the drilling process. When drilling the hole, keep the bit and hole lubricated to prevent chipping. We recommend drilling from both ends of the tile, starting with the black and the drilling half the depth of the tile. Then, turn the tile over and complete the hole. This will prevent the glass from chipping as the drill bit exits the tile.

Material Inspection and Substrate Preparation

These instructions are provided as a general guideline for installing 3X6 glass subway tile; some installations require different or more detailed specifications. An experienced, professional tile installer who is familiar with the following procedures should perform the work for such installations. Please read and understand these instructions before beginning any work.

Verifying Dye Lot Consistency

The owner or end user is responsible for determining the acceptability of the product. Due to the handmade, artistic nature of our product, variation in color, shade, tone, and size is normal.

  • Upon delivery, open and inspect each box of tile.
  • Verify dye lot consistency in the following manner. To establish color control samples, randomly select 5 pieces from your order from different boxes.
  • To assure shade variations are acceptable check the remaining sheets or field tile in your order against the control samples, prior to installation.
  • If ordering additional materials, sample shall be sent to help attempt to match previously ordered material.

Tips To Achieve Better Installations

  • All mortar beds shall cure no less than 7 days prior to glass tile installation.
  • All glass tile installations benefit from extended cure times (48 hours or longer) prior to grouting or foot traffic.
  • All submerged or heavy water use applications shall cure no less than 21 days after grouting before submersion or heavy water use.


The performance of a properly installed thin-set tile application is dependent upon the durability and dimensional stability of the substrate to which it is bonded. The following recommendations are from the Tile Council of North America’s “2007 TCA Handbook for Ceramic Tile Installation” and are general in nature (

  • For large format glass tile installations, horizontal solid blocking shall be installed in the framing every 18" and at all CBU board transitions.
  • Membrane meeting ANSI A108.02-3.8 (2005) high solids, cold applied membrane: ASTM C836 shall be used only with opaque glass tile.
  • All joints on CBU should be taped with the CBU manufactures’ recommended mesh tape and allowed to cure 48 hours prior to installation.

Unacceptable Substrates

  • Single-float mortar bed walls not employing cured scratch coats
  • Poultry netting (chicken wire) or metal lath less than 2.5 lbs. per square yard in wire reinforced mortar beds
  • Wood products, such as plywood, luan, MDF, MDX, press board and composites

Setting Systems

All materials should be used according to manufacturer’s instructions. Due to the translucent nature of glass, the color of the bonding material will impact the ultimate look of the tile. We recommend the use of specific white bonding mortars, some mixed with specific latex admix. See the following list for required thin-sets and follow manufacturer’s recommended cure times for all setting materials. Pools, spas and all submerged applications require a minimum 210 day cure time after grouting and before submersion or exposure to heavy water use.

When mixing setting and grouting materials do not exceed 300 RPM or the manufacturer’s recommendations. Most setting and grouting materials need to slake (sit) 10-15 minutes after mixing and remixed before use.

Select one of these required white Thin-Set Mortar Systems

Acceptable Setting Systems

  • CUSTOM BUILDING PRODUCTS: Premium Plus Thin-Set Mortar mixed with Custom Flex Ultra-Strength Thin-Set Additive.
  • CUSTOM BUILDING PRODUCTS: MegaFlex Crack Prevention Mortar.
  • CUSTOM BUILDING PRODUCTS: MegaLite Crack Prevention Mortar.
  • LATICRETE: 254 Platinum Multipurpose Thin-Set Mortar.
  • FLEXTILE: 52 Versatile Floor Mortar.
  • HYDROMENT: ReFlex Ultra-Premium Latex-Modified Thin Set Mortar.
  • MAPEI: Kerabond Premium Dry-Set Mortar (KER 102) mixed with Keralastic Mortar Additive (KER 310)
  • KERAKOLL: H40 Tenax Single Component Thin-Set.
  • TEC (H.B. Fuller): Super Flex Premium Performance Universal Latex-Modified Thin-Set Mortar.

Unacceptable Setting Systems

  • Organic adhesive (mastic) – due to yellowing and low bond strengths.
  • Epoxy – due to low flexibility, as well as degradation in UV sunlight.

Movement Joints

Movement joints are essential for the success of most tile installations. Follow recommendations on Movement Joints EJ 171-07 in the “2007 TCA Handbook for Ceramic Tile Installation”. Movement joint requirements will vary depending on substrata, climate and size of installation. An architect or design professional should be consulted when specifying the exact number and location of each movement joint. Certain applications may require a different type of sealant.

Acceptable Flexible Joint Fillers

  • HYDROMENT: Chem-Calk 900 One-Part Urethane Sealant
  • KERAKOLL: Sigibuild PU Poly-Urethane Sealant
  • LATICRETE: Latisil 100% Silicone
  • SILAFLEX: 1A or 2C Polyurethane-based Sealant


Install grout mix according to manufacturer’s instructions. Grout joints shall be full and uniformly finished. Due to the impervious quality of glass, the grout will take longer to begin setting-up. For initial cleaning of grout from the tile face, use clean, dry cheesecloth. This wicks additional moisture from the grout and avoids washing out of the joints. Use only a clean, damp sponge for the final cleaning and smoothing of the joints. For final polishing of excess grout haze use a clean, soft cloth.

We recommend using un-sanded grout for installation of the glass tile. The following are a few products we recommend:

NOTE: An acrylic grout admix can improve freeze-thaw resistance. Check with the manufacturer for their recommendation on specific applications.

Anti-Fracture/Waterproofing Membranes

  • CUSTOM BUILDING PRODUCTS: RedGuard Waterproofing and Crack Prevention Membrane
  • LATICRETE: 9235 waterproof & anti-fracture membrane
  • HYDROMENT: Gold Anti-fracture and Waterproofing Membrane
  • TEC: TA-324 Triple-Flex waterproofing/crack isolation membrane