Breakdown of Síðan húsfélagið breytti reglunum lokar þvottahúsið ekki fyrr en klukkan tíu.
Questions & Answers about Síðan húsfélagið breytti reglunum lokar þvottahúsið ekki fyrr en klukkan tíu.
Here síðan means since or ever since in a time sense:
Síðan húsfélagið breytti reglunum ...
= Since the homeowners’ association changed the rules ...
That is different from the very common adverb use of síðan, which can mean then, after that, or later.
So in this sentence, síðan is introducing a subordinate clause about a past event that affects the present situation.
This is because Icelandic is a V2 language in main clauses. That means the finite verb usually comes in the second position.
The whole opening clause Síðan húsfélagið breytti reglunum takes the first slot. So the main clause verb has to come next:
Síðan húsfélagið breytti reglunum | lokar | þvottahúsið ekki fyrr en klukkan tíu.
If you said the main clause by itself, without the opening clause, you would normally say:
Þvottahúsið lokar ekki fyrr en klukkan tíu.
So the subject þvottahúsið is still the subject, but it comes after the verb because of normal Icelandic main-clause word order.