بسم الله الرحمن الرحيم
(Fatwa: 993/794/D=09/1436)
Salah shall be valid if she does sajdah over a solid thing that is one span high. In case she faces difficulty in doing so then she should do sajdah while sitting with the gesture of head i.e. by bowing down her head.
قال فى الدر ان كان الموضوع مما يصح السجود عليه كحجرة مثلا ولم يزد ارتفاعه على قدر لبنة او لبنتين فهو سجود حقيقى . ج 2، ص 569
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
