I Am About To Install A T-Bar Ceiling In My Basement.. The Joist Are 2.5 Inches Above The Main Beam.. I Want To Know Do I Measure 4 Inches Down From The Joist Or 4 Inches Down From The Main Beam In Order To Put My Perimeter Track Around The Wall.. 4 Inches From The Main Beam Would Probably Bring My Ceiling A Little To Low.. Wondering If I Could Cheat A Little & Bring My Perimeter Track 4 To 4.5 Inches Below The Joist.. That Would Put The Perimeter Track 2 Inches Below The Main Beam.. Just Wondering If I Would Have any Problem Getting The Tiles In The Grid Like That With A 2 Inch Clearence Below The Beam & 4.5 Inch Everywhere Else.. Thanking U In Advance.

Run your level line at 4.5'' from floor joists. You will have no problem getting tile into grid under the beam if you have 2'' clear space. You will have to put these tiles in through another tile area and slide them into place. You could go as close as 1'' and still get them in.

Chuck