b'ASK THE EXPERTSAsk the Experts Q&As are culled from member inquiries to NTCAs Technical Support staff. To become a member and make use of personal, targeted answers from Technical Support staff to your installation ques-tions, contact Jim Olson at email@example.com.QUESTION QUESTIONWeareonajobwonbyaWeregoingtouseanuncou-fl plingmembraneonawoodsub- ooring contractor who will install sheetvinylorporcelaintileonafl oor. I know when its a brand new concretefl Wearetryingtosubfl oorthereshouldbea1/8oor. determinewhoidentifi eswheregap. This house has had the sub-theconstructionjointsareandfl oor in place for the past 10 years. how they will be treated, if it is notDo I still need to cut the 1/8 gap? provided in the drawings.ANSWERANSWER It is a best practice to have the The person with knowledge ofgapinplacebetweenthewood thebuildingandstructurehas(i.e.plywood/osb).Althoughthe toidentifywherethejointsarewood structure has been in place and how they will be honored orfor 10 years, it has likely expanded treated depending on the type ofor contracted over those years and joint.may do so again. The uncoupling If there are drawings and speci- membrane will likely protect from fi forthejob,theprofes- that expansion and contraction butcations sionalthatanalyzedthestructureI suggest following the best prac-to ensure adequacy for a tile instal- tice of opening up the gap.lation and who drew up the speci- Itsprettyeasytodo.Setthe fi is the person responsibledepthofacircularsawtoaboutcations forprovidingthetileinstallation3/16-1/4 deep (just deep enough contractorthedrawingsforloca- so you dont cut the wood tongue tion and identifi cation of honoringoff)andrunthesawdownthe / treating the structural joints. jointsbetweenthesheets.Usea YoucanreferthemtoTCNAgoodcarbidetippedbladethat HandbookmethodEJ-171wherewill give you about a 1/8 kerf or this is further defi ned.cut width. Mark Heinlein, For the ends of the runs near the NTCA Training Director walls, use an oscillating tool to fi n-22 TileLetter | October 2019'