Before commencing with salaat, several things are wajib. If one does not have wudu, then wudu should be made. If there is a need to have a bath, then a bath should be taken. If there is any impurity on the body or clothes, it should be purified. The place where salaat is being offered should also be pure. Apart from the face, hands and feet, the entire body from head to toe should be well covered. One should face the qiblah. An intention should be made for the salaat which one wishes to offer. The salaat should be offered after the entry of that salaat time. All these are prerequisites or conditions for salaat. If any one of these prerequisites are not found, salaat will not be valid.
It is not permissible to offer salaat with a very thin, flimsy or lacy scarf.
If a quarter of a woman’s calf, thigh or arm gets exposed while offering salaat and it remains exposed to the extent that she can read Sub’haanallah three times; then her salaat will break and she will have to repeat it. But if she covers that part the moment it is exposed, her salaat will still be valid. In the same way, if a quarter of any part that is supposed to be covered when offering salaat gets exposed, then the salaat will not be valid. For example, if a quarter of the ear, head, hair, stomach, back, neck, bosom, chest, etc. gets exposed; then the salaat will not be valid.
If the scarf of a girl who has not reached the age of puberty as yet slips off while offering salaat and her head gets exposed, her salaat will still be valid.
If there is any impurity on the body or clothing but water cannot be found anywhere, then the salaat should be offered with the impurity.