▁buildings ▁are ▁constructed ▁by ▁spec ulative ▁office ▁building ▁developers , ▁leaving ▁choice ▁and ▁responsibility ▁for ▁the ▁remainder ▁of ▁the ▁building ▁— ▁the ▁fit - out ▁— ▁to ▁occup ants . ▁The ▁base ▁building ▁normally ▁includes ▁the ▁building ' s ▁primary ▁structure ; ▁the ▁building ▁en velope ▁( ro of ▁and ▁fac ade ) ▁in ▁whole ▁or ▁part ; ▁public ▁circul ation ▁and ▁fire ▁e gress ( lo bb ies , ▁cor rid ors , ▁elev ators ▁and ▁public ▁st airs ); ▁and ▁primary ▁mechanical ▁and ▁supply ▁systems ▁( elect ric ity , ▁he ating ▁and ▁air ▁condition ing , ▁tele phone , ▁water ▁supply , ▁d rain age , ▁gas , ▁etc .) ▁up ▁to ▁the ▁point ▁of ▁contact ▁with ▁individual ▁occup ant ▁spaces . ▁Base ▁buildings ▁provide ▁serv iced ▁space ▁for ▁occup ancy ; ▁Support s ▁is ▁another ▁term ▁for ▁base ▁building . ▁ ▁F it - out ▁( ten ant ▁work ): ▁the ▁physical ▁products ▁and ▁spaces ▁controlled ▁by ▁the ▁individual ▁inhab it ant ▁or ▁occup ant ▁used ▁to ▁make ▁habit able ▁space ▁in ▁a ▁base ▁building . ▁F it - out ▁can ▁change ▁without ▁forcing ▁the ▁base ▁building ▁to ▁change . ▁ ▁Cap acity : ▁the ▁meas urable ▁quality ▁of ▁a ▁base ▁building ▁to ▁accommod ate ▁a ▁range ▁of ▁variations ▁in ▁floor ▁plan ▁and ▁use ▁within ▁the ▁constraints ▁of ▁a ▁given ▁base ▁building . ▁More ▁generally , ▁capacity ▁concerns ▁the ▁degree ▁of ▁Open ▁Building ▁freedom ▁offered ▁by ▁a ▁higher ▁level ▁to ▁a ▁lower ▁level . ▁ ▁References ▁ ▁External ▁links