The Lajnah mentioned that it is not allowed to go out for work when in ‘itikaaf:
What are the conditions of I‘tikaf (seclusion for worship in a Masjid)? Is Sawm (Fast) a condition of I‘tikaf? Is it permissible for a Mu‘takif (one who observes I‘tikaf) to visit a sick person, accept an invitation, tend to his family’s needs, attend a funeral, or go to work?
It is legislated to observe I‘tikaf in a Masjid (mosque) in which congregational Salahs are held. If the Mu‘takif is one of those for whom Jumu‘ah (Friday) Prayer is obligatory and the period of I‘tikaf will include a Friday, it is better for him to stay in a Masjid where Jumu‘ah Prayer is observed. It is not a condition for the Mu‘takif to be fasting. According to the Sunnah (acts, sayings or approvals of the Prophet), the Mu‘takif should not visit the sick during his I‘tikaf, accept any invitation, tend to his family’s needs, attend any funeral, or go to work outside the Masjid, because it was authentically reported that ‘Aishah (may Allah be pleased with her) said:
The Sunnah (action following the teachings of the Prophet) for the Mu‘takif is not to visit a patient, attend a funeral, touch or be intimate with his wife, or leave for any errand unless it is an absolute necessity.
However, they also mentioned that it is allowed for someone to make the intention to do ‘Itikaaf only at night and then go to work in the morning:
We work at a shop that sells clothes. On the last ten days of Ramadan, we cannot observe I`tikaf (seclusion for worship in a Masjid) during the day because of work conditions. Is it valid to observe I`tikaf only at night and work during the day at the shop?
It is permissible to observe I`tikaf even for an hour at a Masjid (mosque) where congregational Salah (Prayer) is offered. It is valid to observe I`tikaf without observing Sawm (Fast) during the time of I`tikaf according to the most correct opinion maintained by scholars.
`Abdullah ibn `Umar (may Allah be pleased with him and his father) narrated on the authority of `Umar ibn Al-Khattab that the latter said, “O Allah’s Messenger, I vowed in Jahiliyyah (pre-Islamic era of ignorance) to observe I`tikaf for a night at Al-Masjid Al-Haram (the Sacred Mosque in Makkah).” Consequently, the Prophet (peace be upon him) said to him: ‘Fulfill your vow.’ Therefore, he performed I`tikaf for one night. (Related by Al-Bukhari and Muslim) This is the wording of Al-Bukhari, vol. 2, p. 260.
Had Sawm been a condition for the validity of I`tikaf, the Prophet (peace be upon him) would not have approved the I`tikaf of just one night without its day. Hence, it is permissible for you to have the intention of observing I`tikaf only at a night without observing it on the day because of the reason you mentioned. In sha’a-Allah (if Allah wills), you will be rewarded according to your deed.
Also Shaikh Salih al-Fawzan (may Allah preserve him) was asked:
May Allah be good to you, is it allowed for the one in ‘Itikaaf to go out to his work then return to his place of ‘Itikaf another time?
“If he stipulates that and his leaving is only a little. As for him going out to his work and returning, then this contradicts/opposes ‘Itikaf except if he stipulates to make ‘Itikaf in the night only or outside the time of his work. If he takes an oath to make ‘Itikaf outside the time of his work, then there is no harm as you heard. If he stipulates this, then there is no preventative. If he stipulates that he will do it outside the time of his work. Yes”.
So you can either do Itikaaf on the weekends and/or when you are not working, or you can do Itikaaf during the nights of the weekdays with the intention for this and go to work in the morning.
And Allah Knows Best
Faisal bin Abdul Qaadir bin Hassan