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Which side goes up, smooth or rough? |
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Either is acceptable, but the smooth side with the nailing pattern of every 8" on center should go up. |
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Can I use Hardibacker ceramic tile backerboard in an exterior application? |
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In accordance with National Evaluation Service Report NER-405, Hardibacker ceramic tile backerboard is not permitted for use in exterior applications. |
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Can I use Hardibacker for fireplaces or barbecues? |
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No. While Hardibacker is an interior non-combustible product, it is often used with barbecues. It is not a recommended or a warranted application. |
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Can I use Hardibacker as a fireplace facing? |
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Yes, Hardibacker can be used as a fireplace facing. Our Hardibacker 1/4" backerboard can be
used as a component in a 1-hour fire resistive construction when installed in compliance with
National Evaluation Report NER-405. Hardibacker and Hardibacker G2 underlayments are
recognized as non-combustible, when tested according to ASTM E 136.
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| Q: |
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Why can't I put Hardibacker directly onto concrete or other subfloors? |
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Hardibacker ceramic tile backerboard is not designed for use over concrete. The minimum
subfloor specified is a 5/8" exterior grade plywood or 3/4" exterior grade OSB (Oriented Strand
Board) subflooring with a deflection not greater than L/360 for live and dead loads over joists that do
not exceed a span of 16" on center. Our installation conforms to TCA (Tile Council of America)
guidelines as well as the tile industry as a whole. The TCA does not recognize compressed sheets
or wood planks as suitable subfloors for a tile application.
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Can you use liquid nails or glue with Hardibacker? |
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No. Where Hardibacker underlayment is being installed over a code-complying subfloor for the
attachment of tile, the underlayment is installed over a 3/32"-1/4" thick bed of bonding mortar and then
nailed down. "Liquid Nails" is not a bonding mortar. It is a structural adhesive generally used to
bond the subfloor to the floor joists just prior to nailing. It creates a very solid joint between the
surface of the floor joist and the subfloor and aids in reducing floor squeak. The properties of Liquid
Nails are such that it is applied via a tube in the form of a bead-like caulking. It is not trowelable
like a mortar and therefore results in high ridges with unsupported areas that can deflect under load,
resulting in cracked tile.
Where the Hardibacker underlayment is being installed directly to wood or metal framing, the use of
a structural adhesive in addition to mechanical fastening can be used. However, the underlayment
must be forced into the structural adhesive almost immediately upon application to insure that no
ridge or crown is formed. The creation of a crown or ridge will result in an additional thickness of
mortar being applied to fill in the valley created by the crown. This will require a longer curing time
and result in a weaker bond between the tile and the mortar and the underlayment. The use of a
structural adhesive does not result in fewer fasteners being required.
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| Q: |
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Why do you have to use thinset between the Hardibacker and the subfloor? |
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Dry set (ANSI 118.1) or acrylic modified thinset (ANSI 118.4) is specified between the Hardibacker
and the subfloor to eliminate any deviations between our product and the subfloor. This
decreases the probability of popping or cracking tiles due to deflection and air pockets.
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What do you mean by "modified thinset"? |
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The modified thinset used with our product is a fortified cement-based mortar and should
specifically conform to ANSI (American National Standards Institute) A 118.4. The thinset can be
fortified in a pre-mixed powder form or with a liquid additive.
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| Q: |
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How do I cut Hardibacker? |
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Hardibacker can be cut with a carbide tip scoring tool, circular saw with a carbide tip, or mechanical Snapper Steelhead Shear. |
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| Q: |
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Why do I have to tape the joints? What is the purpose of the 2" wide tape? |
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The tape will help disperse any movement of the substrate, therefore decreasing the probability of
popping or cracking tiles along the seams. |
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What is the correct fastener pattern for installing Hardibacker? |
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Fasten Hardibacker sheets with proper nails or screws (as listed in "Materials Required" in the
backer installation instructions) every 8" around the perimeter and all supporting studs. Keep
fasteners between 3/8" and 3/4" from sheet edges and 2" in from sheet corners.
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| Q: |
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What type of fastener do you recommend for floor and wall applications of Hardibacker? |
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In compliance with the tile industry, James Hardie recommends 1-1/4" long galvanized or stainless steel roofing nails (0.121" shank x 3/8" HD) or 1-1/4" long corrosion resistant ribbed waferhead
screws (No. 8-18 x 3/8" HD).
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Can I put Hardibacker over linoleum or vinyl composite tile? |
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Yes, Hardibacker can go over linoleum or vinyl composite tile. Even though you may go over vinyl
composite tile, James Hardie does not recommend you install Hardibacker over cushioned vinyl.
Follow Hardibacker floor installation instructions for complete details.
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| Q: |
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Why can't I get the screws to sit flush with the Hardibacker? |
| A: |
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The screws that you are using do not have the power to rout out the material in order for the screw
head to sit flush. Be sure to use the specified screws (1-1/4" No.8-18 by 3/8" HD Hi-Lo S or S-12 for
metal studs, ribbed phil wafer head, self drilling, corrosion-resistant screws). If you continue to have
difficulties, we recommend switching to 1-1/4" galvanized roofing nails
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| Q: |
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Can Hardibacker 1/4" ceramic tile backerboard be used in a shower wall application? Is a vapor barrier required? |
| A: |
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Yes, Hardibacker 1/4" ceramic tile backerboard can be used in a shower. However we recommend
Hardibacker G2 if you need to make a smooth transition to drywall. The underlayment must be
mechanically fastened every 8" on center to the wood or metal studs spaced a maximum of 16" on
center. A vapor barrier is recommended.
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