ANSI A118.15 Mortar (thin-set) added
The 2014 TCNA Handbook for Ceramic, Glass, and Stone Tile Installation has been released, and this year’s edition includes the newest performance designation for tile bonding mortar within the ANSI system: ANSI A118.15 American National Standard Specifications for Improved Modified Dry-Set Cement Mortar. The new mortar standard is important because it enables contractors’ project bids to be compared more evenly – particularly when a higher-performing mortar is needed – because it provides a means for requiring or specifying use of a higher-performing mortar. Previously, many mortars that are now classified as an “A118.15 mortar” would have been categorized under ANSI A118.4, which still exists, but with a slight name change (now the American National Standard Specifications for Modified Dry-Set Cement Mortar).
How does this affect tile contractors?
Specifications that called for an ANSI A118.4 mortar allowed a wide range of mortars in terms of performance. When estimating, contractors would have to decide whether or not to factor in a higher-performing (likely more expensive) mortar. Given the competitiveness of bids, doing so could jeopardize the chance of getting a job by adding cost to a bid that others are not including because it is not required. At the same time, experienced contractors and estimators know that some installations and applications need – or would at least benefit from – a higher-performance mortar, even if the job spec doesn’t require it. With the new A118.15 standard in place, there is a more level playing field. Plus, it could be argued that the consumer and end user will benefit because, when a higher-performing mortar is needed, the job specifications can call for it, and the project is likely awarded to a contractor that included it.
What methods are affected?
In the just-released 2014 Handbook, A118.15 mortar has replaced A118.4 mortar as the minimum requirement for tiling above-ground balconies and decks, pools, and steam showers. For interior above-ground floor installation methods (for example F113A), the mortar requirement depends on whether or not a membrane is being used. If there is no membrane, A118.15 mortar is required – the concept being that having a flexible component in such systems is helpful. If a membrane is used however, an ANSI A118.4 mortar may be used. Similarly, A118.15 mortar is required when a membrane will not be included when using the radiant-heat floor-installation methods and the exterior-wall methods.
Manufacturers of A118.15 mortars are already educating design professionals on when higher-performing mortar is needed and how to specify it. Be on the lookout for updated specs and be sure to bid accordingly.