b'TECHNICALWhy proper substrate preparation is critical for tile and stone installationsBy Mark Pennine, ARDEX Technical ManagerIfyouareanattendeeofourNTCAonlinefreewebinars,thistitle may sound familiar. Thats because back in February, ARDEX Technical Manager Mark Pennine presented an NTCA Webinar on this subject. And since it so perfectly fits the planned topic for this months Technical sec-tion, we decided to excerpt parts of this talk to address the issue of sub-strate preparation. An initial talk on the subject was offered in September. Want to watch that webinar or review the material in this article? Visit the NTCA YouTube channel and peruse our archived presentations there: http://www.youtube.com/c/NationalTileContractorsAssociation.Ed. Proper substrate preparation hasneedaflatter,smoothersubstrate. long been an essential aspect to aTolerancesfortheseproductsare successful tile or stone installation.tighter.Forinstance,substratetol-Buttodaystiletrendsoflarge- erance for tiles with all edges less format and gauged porcelain tilesthan 15 in facial dimension is 1/4 andpanels(GPTP)makeflawlessin10and1/16in12.Butfor substrates even more critical.large-format and gauged porcelain tilesandpanels,thetoleranceis inverse to the sizethe larger the tile,thelesstheacceptabletoler-ance: 1/8 in 10 and 1/16 in 24is industry standard. Natural stone has always required more stringent sur-faceflatnesstolerances.Gauged porcelainpanelrecommendations are following those guidelines.Smaller tiles, like 6 x 6, 8 x 8Installinglarge-formattiles or even 12 x 12 format, allow forismuchmoremanageableand conformingtoinconsistenciesinstress-freewhenself-levelinghas the substrates much easier. Massivebeen done ahead of time. Gauged GPTPproductsdontofferroomporcelainpanelsinstalledona forvariancesinthesubstrateandproperly-prepared substrate results 90TileLetter | May 2020'