Gerunds in Passive Sense

We often use a gerund after the verbs need, require and want. In this case, the gerund has a passive sense.

• I have three shirts that need washing. (need to be washed)
  
• This letter requires signing. (needs to be signed)
  
• The house wants repainting. (needs to be repainted)

The expression "something wants doing" is not normally used in American English.