Yağmur başladığından beri evde kalıyorum.

Because Turkish often uses the present continuous to express an action that started in the past and is still continuing now.

So:

• evde kalıyorum = I am staying at home
• with ... beri = I have been staying at home since ...

In other words, Turkish does not need a separate tense like the English present perfect continuous here.

Compare:

• İki saattir bekliyorum. = I have been waiting for two hours.
• Yağmur başladığından beri evde kalıyorum. = I have been staying at home since the rain started.

It means since it started or since the rain started.

You can think of it as:

• başla- = to start
• -dığı = turns the verb into a clause like that it started
• -ndan = from
• beri = since

So başladığından beri literally works like from the time it started until now.

As a whole:

• Yağmur başladığından beri = since the rain started

Good question. They work together as a set pattern.

In Turkish, beri often follows a word or clause in the ablative case (-den/-dan), especially when talking about time.

So:

• dünden beri = since yesterday
• sabahtan beri = since morning
• geldiğinden beri = since he/she came
• başladığından beri = since it started

So the -dan part marks the starting point, and beri reinforces the meaning since.

It comes from the verb başlamak (to start).

A simple learner-friendly breakdown is:

• başla- = start
• -dık/-dik/-duk/-dük → a clause-forming ending
• -ı / -i / -u / -ü → possessive agreement for his/her/its
• -ndan / -nden → from

Because of sound changes, this becomes:

• başla + dık + ı + ndan
• → başladığından

You do not need to produce that whole analysis every time, but it helps to recognize that verb + -dığı + ndan beri is a common pattern meaning since ... happened.

In this sentence, yağmur is simply the subject of the clause, so it stays as yağmur.

Turkish often forms expressions like:

• yağmur başladığından beri = since the rain started
• okul açıldığından beri = since school opened
• sen geldiğinden beri = since you came

You may later learn more complex noun-clause patterns where the subject can appear differently, but for now the important thing is that yağmur başladığından beri is a normal and natural way to say since the rain started.

Because evde means at home / in the house.

The endings are different:

• evde = in/at home
• eve = to home / to the house
• evden = from home / from the house

Since the meaning is about your location while staying, evde is the correct one:

• evde kalıyorum = I’m staying at home

Kalmak basically means to stay or to remain.

So:

• evde kalıyorum = I am staying at home
• depending on context, it can also feel like I’m remaining at home

It does not mean simply I live at home.
For I live at home, Turkish would more naturally use oturmak or another structure depending on context.

Here, kalıyorum suggests staying there for a period of time, especially because of the rain.

It is built into the verb.

In Turkish, the ending on the verb often shows the subject, so ben (I) is usually omitted unless it needs emphasis.

• kalıyorum = I am staying
• kalıyorsun = you are staying
• kalıyor = he/she/it is staying

So this sentence already means I am staying / I have been staying without needing ben.

If you wanted extra emphasis, you could say:

• Ben yağmur başladığından beri evde kalıyorum.

But usually that is unnecessary.

No, Turkish word order is flexible, though the given sentence is very natural.

Standard order here:

• Yağmur başladığından beri evde kalıyorum.

You may also hear:

• Evde kalıyorum yağmur başladığından beri.

But that sounds more marked or conversational. The original version is the best neutral choice.

A useful point: the verb often comes at the end in normal Turkish sentence order.

Yes. Turkish also has another common way to say since ... with -alı / -eli.

For example:

• Yağmur başlayalı evde kalıyorum.

This also means I have been staying at home since the rain started.

Both are natural, but there can be a slight difference in feel:

• başladığından beri is a very transparent since it started
• başlayalı is a compact and very common since starting/since it started

As a learner, it is useful to recognize both.

Not naturally. This sentence means since the rain started, not because the rain started.

That time meaning comes from ... başladığından beri.

If you wanted because, Turkish would use something like:

• Yağmur başladığı için evde kalıyorum. = I’m staying at home because the rain started.
• Yağmur başladığından by itself can sometimes appear in structures related to reason, but with beri it clearly means since in a time sense.

So in this sentence, the meaning is definitely about duration from a starting point until now.

Yes, and it is very natural.

Compare:

• evde kalıyorum = I am staying at home
• evdeyim = I am at home

So:

• Yağmur başladığından beri evde kalıyorum.
  = I have been staying at home since the rain started.
• Yağmur başladığından beri evdeyim.
  = I have been at home since the rain started.

The second one focuses more on your state/location; the first one emphasizes the action or situation of staying there.

A fairly literal version would be:

• Since the rain started, I am staying at home.

Or even more literally:

• From when the rain started, I am staying at home.

That literal version is not the most natural English, but it helps show how Turkish is structured.

Natural English:

• I have been staying at home since the rain started.