b'ASK THE EXPERTSlimestone can be a tricky stone forbraneisintactoranewmem-a wet area. brane is applied and connected Therearegaugedporcelaintileto the panpanels(GPTP)thatcanbeapplied Take a look at TCNA Handbookinatile-over-tile,direct-bondsitu- methods TR418 and TR 420 for ationwithoutadditionalfasteners.ShowerReceptorRenovation You may want to suggest your clientdetailsconsiders GPTP as an alternative. I FollowEJ-171MovementJoint can put you in contact with GPTPGuidelinesmanufacturers/distributors if needed.Mark Heinlein, NTCA Technical In the meantime, I am sure youDirectorknow these thingsbut here are a few reminders for any tile-over-tileANSWER 2installations in a shower situation: HereareafewmoreitemsforEnsuretheexistingtileinstal- your consideration.lation/substrateissuitablywellThatslabofJerusalemlimestone bonded, plumb, fl at, etc., to sup- would weigh approximately 205 lbs. port the new installation dry and would increase when wet. Ensurethewaterproofi ngmem- There are three classifi cations for limestoneunderASTMC568as follows:e-Learning ProgramClassI(lowdensity)7.5%to Industry and product information12%A-9007-08202020 LATICRETE International, Inc. All trademarks shown are the intellectual properties of their respective owners.in short, easy segmentsClass II (medium density) 3% to 7.5%Train from the comfort of your Class III (high density) up to 3%home or ofce anytime The fi nish of the stone (normally Fast and easy to access,honed) and the density of the stone listen to, and complete will determine its porosity.When it is installed in a wet envi-ronment (follow Marks advice on the installation), it should (must) be sealed using a breathable penetrat-ingsealerperthemanufacturers recommendationsonthenumber ofcoatsanddrytime.Jerusalem limestonewillrequireongoing Register today at maintenance to keep it sealed and laticrete.com/university more easily cleaned. ScottCarothers,Directorof Certifi cation and Training, CTEF22 TileLetter | September 2020'