Fire rated ceiling runner system with expansion accommodating means

Claim 1

In a suspended grid system having double-web inverted tee runners, decorative trim caps concealing otherwise exposed runner portions, and ceiling tile supportingly engaged by support flanges of the inverted tee runners, the improvement comprising: slidable decorative trim caps having a bottom flange contacting bottom surfaces of the runner support flanges and having reflanges rebent to face each other and loosely engage side edges of the runner support flanges wherein the trim caps are thereby slideably engaged to the support flanges of said inverted tee runners and whereby upon longitudinal expansion of the inverted tee runner due to exposure to sufficient heat the support flanges slide within the trim cap; cross-runners terminated short of main runners at grid intersection points to provide an expansion gap of sufficient distance to accommodate longitudinal expansion and avoid buckling in the cross-runner; slidable grid intersection connecting means projecting longitudinally from web portions of cross-runners connecting opposing cross-runners to main runners whereby cross-runners are supported by main runners but are allowed to slide in opposite directions upon longitudinal expansion of the cross-runner to thereby maintain support for ceiling tile; main runners having slidable connector joints at spaced intervals along the length of the runner wherein the support flanges are terminated at connector joints to provide an expansion gap of sufficient distance to accommodate longitudinal expansion of the main runner upon exposure to heat and thereby prevent buckling and disengagement from ceiling tile; and, a continuous decorative trim cap grid surface wherein at all expansion gaps the decorative trim caps extend throughout said gaps to thereby conceal otherwise exposed openings where runner portions terminate to create the gaps.

Claim 9

A method for improving a suspended ceiling grid system having inverted tee runners, decorative trim caps concealing otherwise exposed runner portions, ceiling tile supportingly engaged with support flanges of the inverted tee runners, and controlled buckling means at locations along inverted tee runners, wherein said method provides accommodation of longitudinal expansion of inverted tee runners upon exposure to heat and comprises the following steps: replacing decorative trim caps with slidably engaging decorative trim caps having a bottom flange contacting bottom surfaces of the runner support flanges and having reflanges rebent to face each other and loosely engage side edges of the runner support flanges whereby upon longitudinal expansion of the inverted tee runners the support flanges are free to slide within the trim cap; terminating cross-runners short of main runners at grid intersection points to thereby provide an expansion gap of sufficient distance to accommodate longitudinal expansion and avoid buckling of the cross-runner; providing slidable intersection connecting means projecting longitudinally from web portions of the cross-runners which connect opposing cross-runners to main runners whereby cross-runners are supported by main runners but are allowed to slide in opposite directions upon longitudinal expansion of the cross-runner to thereby maintain support for ceiling tile; adding slidable connector joints to main runners at spaced intervals along the length of the runner by; terminating the support flanges that connect the joint locations to thereby provide an expansion gap of sufficient distance to accommodate longitudinal expansion of the main runner upon exposure to heat; offsetting main runner web portions to allow them to slide past one another upon longitudinal expansion; and, connecting offset web portion and sliding engagement to maintain support for the main runner across the connector joint; and, extending decorative trim caps throughout all expansion gaps to provide a continuous decorative grid surface and conceal otherwise exposed openings where runners have been terminated to create the expansion gaps.

Claim 10

A method for improving a suspended ceiling grid system having inverted tee runners, decorative trim caps concealing otherwise exposed runner portions, ceiling tile supportingly engaged with support flanges of the inverted tee runners, and controlled buckling means at locations along inverted tee runners, wherein said method provides accommodation of longitudinal expansion of inverted tee runners upon exposure to heat and comprises the following steps: replacing decorative trim caps with slidably engaging decorative trim caps having a bottom flange contacting bottom surfaces of the runner support flanges and having reflanges rebent to face each other and loosely engage side edges of the runner support flanges whereby upon longitudinal expansion of the inverted tee runners the support flanges are free to slide within the trim cap; terminating cross-runners short of main runners at grid intersection points to thereby provide an expansion gap of sufficient distance to accommodate longitudinal expansion and avoid buckling of the cross-runner; providing slidable intersection connecting means projecting longitudinally from web portions of the cross-runners which connect opposing cross-runners to main runners whereby cross-runners are supported by main runners but are allowed to slide in opposite directions upon longitudinal expansion of the cross-runner to thereby maintain support for ceiling tile; adding slidable connector joints to main runners at spaced intervals along the length of the runner by; terminating the support flanges that connect the joint locations to thereby provide an expansion gap of sufficient distance to accommodate longitudinal expansion of the main runner upon exposure to heat; offsetting main runner web portions to allow them to slide past one another upon longitudinal expansion; and, connecting offset web portion and sliding engagement to maintain support for the main runner across the connector joint; and, extending decorative trim caps throughout all expansion gaps to provide a continuous decorative grid surface and conceal otherwise exposed openings where runners have been terminated to create the expansion gaps.