foundry flats thin brick installation guide


For additional installation information, refer to The Brick Industry Association (BIA)


  • surfaces should be structurally sound and free of coatings, loose debris and other bond-impeding substances
  • max. variation from plane, ¼ in. in 10 ft (6 mm in 3.05 m)
  • max. deflection of L/360 for wall stud framing



For interior applications

installation methods should conform to the tile council of america “handbook for ceramic tile installation” (current edition).


For exterior applications

Water-Resistive Barrier

  • for exterior applications over stud-framed assemblies, install two layers or one layer with a drainage mat


Flashing and Weeps

  • for exterior applications, install corrosion-resistant flashing, integrated with the water-resistive barrier at through-wall penetrations, substrate transitions and terminations of adhered veneer
  • install weep screed or flashing of corrosion-resistant material at base of adhered veneer, with vertical leg or attachment flange extending at least 3½ in. (89 mm) vertically
  • thin brick - use brick complying with ASTM C1088, with Type and Grade as appropriate for project requirements


Mortar and Adhesive

  • use ASTM C270, Type S, mortar applied to a thickness of ⅜ to 1¼ in. (10 to 32 mm) or one of the following with a minimum shear strength between the thin brick and substrate of 50 psi (345 kPa):
    • ASTM C270, Type S, mortar modified with latex or other suitable polymers
    • modified mortar complying with ANSI A118.4, LatexPortland Cement Mortar
    • non-sagging adhesive compatible with masonry and substrate surfaces


Movement Joints

  • extend movement joints through thickness of entire veneer assembly, for full length or height of veneer, including parapets
  • space no more than 18 ft (5.5 m) o.c. in either direction
  • max. area between movement joints should not exceed 144 sq ft (13.4 m²) or length-to-height or height-to-length ratio of 2½ to 1 • align veneer movement joints directly over substrate movement joints
  • for proprietary modular and prefabricated panels, follow manufacturer’s instructions
  • see Technical Note 18A for recommended placement of additional movement joints


Installation Methods

  • use Table 1 to determine an appropriate thin brick installation method for substrate wall and application. Use one of the following installation methods:

- Thick Set:

  • attach reinforcing lath or mesh to substrate and apply scratch coat of mortar or modified mortar in one or two layers to a nominal thickness of ½ to ¾ in. (12 to 19 mm)
  • to scratch coat, apply bond coat of mortar or modified mortar to nominal thickness of ⅛ in. (3.2 mm), and groove with notched trowel


- Thin Set:

  • use cement backer board with treated joints as substrate for exterior applications over wood or steel studs
  • apply bond coat of modified mortar to a nominal thickness of ⅛ in. (3.2 mm) or non-sagging adhesive in accordance with adhesive manufacturer’s instructions


Thin Brick Placement

  • use either of the following:
    • completely cover back of thin brick when using mortar or modified mortar or, when using adhesive, follow manufacturer’s instructions or apply 1 in. diameter (quarter-sized) dabs at each end
    • firmly press or tap thin brick into mortar or adhesive while maintaining joint width and coursing

Grout Selection

the slight movement of foundry flats during the firing process creates enough variation to require a 3/8" grout joint. in turn, this grouted finish makes for the traditional surface expected in a brick-like installation.

At clé, we suggest using Mapei Flexcolor CQ, which is intended for unglazed tiles, in the shades "timberwolf", "bamboo", "brick red" and "charcoal". by simply interchanging any of these grout shades with any of the foundry flat colors- you can produce a myriad of color combinations and surfaces.

additionally, grout can also serve as a more pronounced design element should the specifier prefer a more rustic surface, mimicking a historical patina. this can be acquired by the deliberate application of grout film which coats random areas of the flats creating a much more rough and "coated" brick surface. 

this application requires direction from the architect, designer or homeowner.


Mortar/Grout Joint Fill

  • force mortar to fill joints as thin brick are placed or fill joints using a grout bag, mortar gun or other mortar delivery device
  • when thumbprint hard, tool with concave, vee or grapevine profile jointer
  • it is recommended that a 3/8" grout joint be used for clé foundry flats. smaller grout spacing can be used including “a tight joint”; however, additional tiles will be required to cover a given area. narrow grout spaces accentuate tile irregularities. note: epoxy grout is not recommended however, should you choose to use epoxy grout, grout release is required to maintain the original surface. use a grout bag to minimize excess grout and decrease cleanup. work clean!


During Construction

  1. proper care should be taken during construction to keep the wall free of mortar and grout smears. Grout left on the wall for even short periods of time become difficult to remove. Use a soft bristle brush immediately after tooling to remove excessive mortar. Avoid cleaning motions that press the mortar and grout into the face.
  2. cover the wall at the end of each working day. Failure to prevent moisture from entering the wall may result in efflorescence and other leaching problems.
  3. protect the wall from dirt and mortar splatter.
  4. store brick above the ground to protect from soil contamination



when your installation is new, your contractor will remove excess grout from the surface of the brick. the sooner the foundry flats is cleaned after grouting- the easier it will be to clean the tile surface.

another way to clean the foundry flats surface from installation debris and grout to brush down the surface with a bristle brush and water.

there are also tradespeople that would suggest cleaning with a chemical cleaner. We don’t recommend this, as it has the ability to damage the tiles.

Cleaning instructions-

  • for flats installed in the morning- clean flats in late afternoon.
  • for flats installed in afternoon – clean flats next morning.
  • begin at top of installation, soak top surface of flats with clean water through to bottom tiles.
  • when surface is all wet, scrub face of tiles with a bristly brush.
  • rinse surface with water, afterward.
  • take care not to soak tiles through to the setting material.
  • if this happens, it could encourage efflorescence.

Grout Film as Design:

alternately, for clients that want to enjoy the beauty of instant patina by leaving the grout film or applying excess grout film, the surface finish and maintenance will be completely different. In this case, you would want to insure that you have selected the correct grout color for your “patina” and also to instruct the contractor for the depth of patina you will want your grout film to apply.

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