▁doors ▁of ▁greater ▁height . ▁Old er ▁buildings ▁often ▁have ▁smaller ▁doors . ▁ ▁Th ick ness : ▁Most ▁pre - fab ric ated ▁doors ▁are ▁ 1 ▁ 3 / 8 " ▁thick ▁( for ▁interior ▁doors ) ▁or ▁ 1 ▁ 3 / 4 " ▁( ex terior ). ▁ ▁Cl os ets : ▁small ▁spaces ▁such ▁as ▁clos ets , ▁dress ing ▁rooms , ▁half - b ath s , ▁storage ▁rooms , ▁cell ars , ▁etc . ▁often ▁are ▁accessed ▁through ▁doors ▁smaller ▁than ▁passage ▁doors ▁in ▁one ▁or ▁both ▁dimensions ▁but ▁similar ▁in ▁design . ▁ ▁Gar ages : ▁Gar age ▁doors ▁are ▁generally ▁ 7 '- 0 " ▁or ▁ 8 '- 0 " ▁wide ▁for ▁a ▁single - car ▁opening . ▁Two ▁car ▁gar age ▁doors ▁( s ometimes ▁called ▁double ▁car ▁doors ) ▁are ▁a ▁single ▁door ▁ 1 6 '- 0 ". ▁Because ▁of ▁size ▁and ▁weight ▁these ▁doors ▁are ▁usually ▁section al . ▁That ▁is ▁split ▁into ▁four ▁or ▁five ▁horizontal ▁sections ▁so ▁that ▁they ▁can ▁be ▁raised ▁more ▁easily ▁and ▁don ' t ▁require ▁a ▁lot ▁of ▁additional ▁space ▁above ▁the ▁door ▁when ▁opening ▁and ▁closing . ▁There ▁are ▁single ▁piece ▁double ▁gar age ▁doors ▁found ▁in ▁some ▁older ▁homes . ▁circa ▁ 1 9 5 0 ' s ▁ ▁Europe ▁ ▁The ▁standard ▁D IN ▁doors ▁are ▁defined ▁in ▁D IN ▁ 1 8 1 0 1 ▁( pub lished ▁ 1 9 5 5 – 0 7 , ▁ 1