Radical 宀 ("Roof")

宀 is called 宝盖 (bǎo gài) in Chinese and is often referred to as the "roof" radical in English. It is a meaning element related to "house". The pinyin is mián (mian2). As a radical, it always appears on the top of the character. Here are some examples of Chinese characters containing 宀: 

House is regarded as a good, safe place, so the following characters contain 宀, too: 
安 – ān – peaceful, quiet 
定 – dìng – stable, steady 

NOTE: Please note the difference between 宀 and 穴 radicals! 
E. g., in these two commonly used character 穴 is a radical – not 宀:
空 – kōng; kòng – empty, vacant / to have spare time 
窗 – chuāng – window 

Chinese words containing characters with 宀 radical 

246 characters are found under this radical in the standard Chinese Kangxi Dictionary. They are present in many words related to house (place of living). 
家庭 – jiā tíng – family, household 
家具 – jiā jù – furniture 
家务 – jiā wù – household duties 
卧室 – wò shì – bedroom 
浴室 – yù shì – bathroom 
宅子 – zhái zi – residence 
故宫 – gù gōng – Gugong (the Former Palace in Beijing) 
宿舍 – sù shè – dormitory 
公寓 – gōng yù – block of flats