Answered by Ustadh Salman Younas
Question: Can sisters wear dreadlocks or put synthetic extensions in their hair?
Answer: assalamu `alaykum
It would be permitted for women to have dreadlocks. Further, a woman with dreadlocks would not have to undue them when performing the ritual bath (ghusl). All she needs to ensure is that water reach the roots of her hair.
As for using synthetic extensions, this would be permitted. For more details regarding the specific issue see: Rulings Related to Wigs and Hair Extensions
Salman
Checked & Approved by Faraz Rabbani