Is it permissible for a woman to have her layered? Although this is usually done for adornment, my intention is mainly to thicken my hair as it is very very thin and having the hair cut (slightly) in layers usually thickens the hair.  May i stress that i am in full hijaab and no ghair mahram would ever see my hair.

In the name of Allah, Most Compassionate, Most Merciful,

There are two main reasons given by the scholars for it not being permissible for women to cut their hair.

The first being imitation of men. Ibn Abbas (radi allahu anhu) narrates that Allah’s Apostle cursed those men who imitate women and those women who imitate men. (Sahih Bukhari: 7.773)

The second being the imitation of the disbelievers in which regards the Prophet (salla lahu alayhi wa sallam) said: He who copies any people is one of them. (Abu Dawood: 1856)

For the above two reasons, the jurists have prohibited the cutting of hair for women. It is for this reason they considered such women to be cursed. “If a woman cuts her hair, she will be sinful and cursed. In al-Bazzaziyya it is added: “Even with the permission of the husband, as there is no obedience to the creation in disobeying the Creator.” (Raddul Muhtar)

However, if a woman trims her hair slightly in a way that she did not contravene any of the above two conditions, then this could be permitted. Therefore if layering does not contravene any of the two conditions above then it would be permissible. However in my humble opinion layering contravenes the second condition of imitating the non-believers and therefore should be avoided despite if one is in hijaab.
Only Allah knows best

Sayeedur Rahman

Darul Ifta, Birmingham