مناسك حج - مكارم شيرازى، ناصر - الصفحة ٦٢ - Process of Ihram
Article ٧٩- It is an obligatory precaution not to tie loincloth around the neck( but tying it around the waist has no problem )and the best way is to tie a belt over the Izar.
Tying two sides of Rida, also fastening that by a pin, or putting a piece of stone in one side and fastening that to the other side with a string( as it is common among some of Hajjis )has no problem, although it is better to renounce these acts.
Article ٨٠- If a pilgrim wears Ihram while he/ she has shirt or other common cloths on because of ignorance or forgetfulness, then his/ her Ihram is correct, but he/ she should immediately remove that clothe and wear only Ihram clothing, and if this act has performed deliberately, then after removing the clothes it is a precaution to make the intention and say Labbayk again.
Article ٨١- Whenever a pilgrim puts on a shirt after wearing Ihram clothing because of ignorance about the issue or forgetfulness, he/ she should remove that clothe from the bottom and if it is not possible he/ she should tear the clothe and remove it.
Article ٨٢- It is not obligatory to have Ihram clothing on all the time and the pilgrim can remove that for washing or changing or any other purposes.