Assuming the status of a Beit Knesset or Beit Medrash

Question

I heard Beit HaKnessiot and Medrashot have certain laws like you can't eat or sleep inside a Beit Knesset, for example, and others for Beit Medrash.

Now I heard our synagogue is like a Beit HaMedrash that was not built with the intention to be a Beit Knesset or Beit Medrash, because it was originally built as a garage. Now we pray and learn in it.

So how does a place that wasn't build to be a Beit Knesset or Beit Medrash assume the status of a Beit HaKnesset or Beit HaMedrash where all these laws apply? And what if you don't add anything to the structure like any renovations or add any decorations? Do you have to go inside and declare "This place is a Beit HaKnesset or Beit Medrash", or does it assume its status by the actions you do inside, like praying or learning more than 3 times?

Answer 1

The Shulchan Aruch 153:8 says that by stating that it’s a Beis HaKnesses is enough to make it as such but it doesn’t receive the holiness (which precludes it from reverting back) unless a prayer was held there as well. However, if the declaration was made for a specific time then it is only dedicated for that time

בנו בית סתם והקדישו אח"כ לב"ה דינו כב"ה אבל אינו קדוש עד שיתפללו בו אפי' אם בנאוהו לשם ב"ה וכיון שהתפללו בו אפי' אורחים לפי שעה כיון שהיה מיוחד לתפלה קדוש ואם לפי שעה הקדישו הכל לפי מה שאמרו:

If they built a regular house and sanctified it afterwards to be a synagogue, its laws are like [that of] a synagogue; but it is not holy until they pray in it, even if they built it as a synagogue. But once they prayed in it - even guests, temporarily - since it was designated for prayer, it is holy. [However], if they sanctified it temporarily [through a stipulation], it is all according to what they said

See also MB there as well as the Biur Halacha 151:11