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ADVANTAGES
Freeze thaw stable
Interior and exterior
Increased flexibility
Non sag for wall areas
Bonds to most surfaces
Contributes to LEED projects
Lightweight and easy to trowel
Superior adhesion for porcelain tile
Thin Set or Medium Bed performance
Available in both gray and white colors
Excellent for walls and large format tile
Same coverage as a typical 50# mortar
Exceeds ANSI A 118.4 for Latex Portland Cement Mortar and 118.11 for EGP Latex Portland Cement Mortar
SUITABLE SUBSTRATES
| Concrete |
Concrete Masonry |
| Cement Mortar Beds |
Cement Plaster |
| Ceramic Tile and Stone |
Brick Masonry |
| Cement Backer Board** |
Cement Terrazzo |
| Exterior Grade Plywood* |
Gypsum Wallboard* |
| Gypsum Mortar Bed*** |
*Interior Use Only
** Consult cement backer board manufacturer for installation recommendations and to verify
acceptability for exterior use.
*** Mer-Krete's Fracture-Guard 5000 crack isolation membrane is required for this installation.
Consult Mer-Krete's Technical Department for gypsum mortar bed recommendations using Mer-Krete
Fracture-Guard 5000 membrane.
LIMITATIONS
Do not use 820 Mer-Lite Thin Set below 40ºF (4ºC) or above 95ºF (35ºC). Use caution; do not
allow mortar to freeze for the first 72 hours. Do not soak tiles previous to installation.
820 Mer-Lite Thin Set must not be used to apply over asphalt sheeting, vinyl covered wall board,
Masonite®, cement asbestos board, metal, glass, plastic, or other unstable substrates.
Improperly cured or wet plywood, particle board or strip wood are not suitable substrates.
Installations that will be continually wet like swimming pools, fountains and gang showers, the
completed installation should be cured a minimum of 14 days and allowed to dry before exposure to
water. For white or light colored marbles use 820 Mer-Lite Thin Set White mortar. Some dimensional
stone tile like green and red marbles may warp when installed with water based setting materials.
These water sensitive stone tiles should be installed with Mer-Krete ProEpoxy. For use of 820 Mer-Lite
Thin Set over additional substrates or situations not mentioned in these instructions, contact
Mer-Krete's Technical department.
TECHNICAL DATA
APPLICABLE STANDARDS
Mer-Krete's 820 Mer-Lite Thin Set meets or exceeds industry requirements ANSI A118.4 for Latex
Portland Cement Mortar and 118.11 for EGP Latex Portland Cement Mortar. Follow ANSI A108.5 for
installation.
INSTALLATION
SURFACE PREPARATION
All surfaces must be between 40°F (4°C) to 95°F (35°C) and structurally sound
(deflection not to exceed 1/360 of the span), dry clean and free from oil, grease, wax, paint, old
adhesives, sealers and curing compounds. Any contaminates which inhibit proper bond must be removed.
Substrate preparation should be completed following ANSI A108.01 (General Requirements: Subsurfaces
and Preparation by Other Trades). All substrates should be plumb and true, surface deviation should not
exceed ¼" in 10'. Patching, leveling or areas requiring a mortar bed should be prepared using Mer-Krete's
Underlayments. Movement (Expansion) joints should be provided to comply with TCNA method EJ 171.
Plywood Substrates
Maximum joist spacing should be 16" on center. Plywood should be exterior grade only. Maintain a gap
of 3/16" between plywood underlayment sheets edges and all that abut walls, columns, posts and adjacent
sheets. All plywood installations should be use in interior areas only and protected from exposure
to moisture.
Cement Substrates
All concrete substrates should be cured a minimum of 28 days. Smooth steel troweled floors should be
roughed up using mechanical chipping, scraping or shot blasting. Dampen porous or dry concrete previous
to installation of tile. Do not leave puddles or standing water.
Membranes
820 Mer-Lite is suitable over Mer-Krete Systems membranes like Hydro-Guard 2000, Hydro-Guard One,
Fracture Guard 5000, Sound Shield 7000, Sound Shield PNS 40 and Sound Shield PNS 90. Low absorption
membranes may require longer cure times.
Cement Backer Board
Follow cement board manufacturer's instructions.
MIXING
For excellent non sag and medium bed characteristics:
In a clean container, add approximately 5 quarts (4.7 liters) of clean potable water. Then add the
contents of the 30 lb. (13.608 kg) 820 Mer-Lite Thin Set mortar. Mix thoroughly by hand or with a slow
speed mixer to a smooth, thick, trowelable consistency. Allow mortar to slake for approximately 5 to 10
minutes, and then remix before using. Remix without adding additional water or powder.
For thin set characteristics:
In a clean container, add approximately 5 ½ quarts (5.2 liters) of clean potable water. Then add the
contents of the 30 lb. (13.608 kg) 820 Mer-Lite Thin Set mortar. Mix thoroughly by hand or with a slow
speed mixer to a smooth, thick, trowelable consistency. Allow mortar to slake for approximately 5 to 10
minutes, and then remix before using. Remix without adding additional water or powder.
Mortar consistency shall be such that when applied with the recommended notched trowel to the substrate,
the ridges formed in the mortar do not flow or slump. During use, stir mortar mix occasionally. Do not temper
with additional water. Do not add latex liquid to 820 Mer-Lite Thin Set.
APPLICATION
Apply mortar to the substrate with the flat side of the trowel, with enough pressure to firmly work into
the surface. With a notched trowel, immediately follow with a heavier coat of material using the appropriate
trowel and enough mortar to provide 100% coverage to the back of the tile. Some extruded or lug back tiles
back-buttering of tiles may be required. Do not spread more mortar then can be covered in 20 minutes or before
the mortar skins over. It is advised that during the installation, remove a tile to insure the mortar has not
skinned over and check the tile and substrate mortar coverage. Comb the mortar using an appropriate notched
trowel in one direction. Place tiles in mortar, slide back and forth perpendicular to the ridges (NTCA "Trowel
and Error" method) to insure proper coverage. Do not adjust tiles set in mortar after 15 minutes.
CLEANING
Water is all that is needed to remove any uncured mortar from tiles, tools and equipment.
AVAILABILITY
Mer-Krete 820 Mer-Lite Thin Set is available at leading tile houses and construction distributors. Contact
Mer-Krete Systems for the name of the nearest dealer.
WARRANTY
5 year, 10 year and Limited Lifetime warranties are available. Contact Mer-Krete technical department for
specific warranty information. Mer-Krete Systems warrants that this product meets applicable ANSI standards
in force at the time of manufacture.
MAINTENANCE
None required, but installation performance and durability may depend on properly maintaining products
supplied by other manufacturers.
TECHNICAL SERVICES
Mer-Krete Systems maintains Technical Field Representatives available throughout the country.
Call 1-(800) 851-6303 for the nearest representative.
FILING SYSTEMS
Mer-Krete Architectural Product Catalog and CD Rom.
www.merkrete.com
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