Aunque el cabecero parecía firme, mi padre dijo que habrá que cambiar la tuerca si el somier vuelve a hacer ruido.

These are all furniture/mechanical words:

• el cabecero = the headboard
• el somier = the bed base / slatted bed frame
• la tuerca = the nut in a nut-and-bolt fastening

In Spain, somier is a very common word for the structure under the mattress.

Aunque means although / even though.

It introduces a contrast:

• Aunque el cabecero parecía firme... = even though the headboard seemed solid...
• ...something is still wrong, because the father says a part may need changing.

So aunque sets up the idea: it looked fine, but apparently there may still be a problem.

Parecía is the imperfect, and it fits well here because it describes an ongoing impression or appearance in the past.

• parecía firme = it seemed firm / it looked firm
• This is descriptive background information.

If you said pareció firme, that would sound more like a completed event or a specific moment when it seemed firm. Here, the speaker is describing the state of things rather than a single punctual event, so parecía is more natural.

After aunque, Spanish can use either indicative or subjunctive, depending on meaning.

Here, parecía is in the indicative because the speaker is treating it as a real, known fact or observation:

• Aunque el cabecero parecía firme... = although the headboard did seem firm...

If the speaker were expressing something hypothetical, uncertain, or not accepted as true, the subjunctive could appear in other contexts. But in this sentence, the firmness is presented as an actual appearance in the past.

Habrá que + infinitive is an impersonal structure meaning:

• it will be necessary to...
• we’ll have to...
• someone will need to...

So:

• habrá que cambiar la tuerca = the nut will have to be changed / we’ll have to change the nut

Important points:

• haber que is impersonal
• it does not say who has to do it
• it is very common in Spanish for giving a general necessity

Related forms:

• hay que cambiar = it is necessary to change
• había que cambiar = it was necessary to change
• habrá que cambiar = it will be necessary to change

This is a very good question, because both can make sense depending on perspective.

• dijo que habrá que cambiar... keeps the future-looking idea alive from the speaker’s current point of view or from the situation being discussed. It suggests: my father said that we’ll have to change it.
• dijo que habría que cambiar... sounds a bit more like reported speech viewed from the past: my father said that it would be necessary to change it.

So habrá que is not wrong here. It keeps the necessity linked to a future possibility that is still relevant, especially because the condition si el somier vuelve a hacer ruido has not yet been resolved.

In Spanish, after si for a real future condition, you normally use the present indicative, not the future.

So Spanish says:

• si vuelve a hacer ruido = if it makes noise again

Even though the meaning is future in English, Spanish prefers:

• si + present indicative
• main clause with future or another appropriate form

Examples:

• Si llueve, nos quedaremos en casa.
• Si vuelve a hacer ruido, habrá que cambiar la tuerca.

Using si volverá would be incorrect in standard Spanish for this kind of condition.

Volver a + infinitive means to do something again.

So:

• volver a hacer ruido = to make noise again
• si el somier vuelve a hacer ruido = if the bed base starts making noise again / makes noise again

This is a very common structure:

• volver a intentar = to try again
• volver a llamar = to call again
• volver a decir = to say again

In Spanish, the normal expression is hacer ruido = to make noise.

So:

• El somier hace ruido = the bed base makes noise / is noisy

Spanish uses hacer in many expressions where English uses other verbs:

• hacer ruido = make noise
• hacer daño = cause pain / do harm
• hacer una pregunta = ask a question

So tener ruido would not sound natural here.

Here firme means something like:

• firm
• solid
• stable
• secure

It does not mainly mean hard in the sense of physical hardness.

So el cabecero parecía firme means the headboard seemed well-fixed or stable, not soft or loose. In this context, firme is about stability rather than texture.

Spanish uses definite articles very often when talking about specific, identifiable objects.

Here, the speaker is talking about particular parts of a specific bed:

• el cabecero = the headboard
• la tuerca = the nut
• el somier = the bed base

These are not random items; they are known parts of the situation being discussed. That is why the definite article sounds natural.

Also, mi padre does not need an article because possessives like mi already identify the noun.

Yes. Spanish is flexible here.

You could say:

• Si el somier vuelve a hacer ruido, mi padre dijo que habrá que cambiar la tuerca.

That would still be grammatical. The original order simply emphasizes the contrast first:

• Aunque el cabecero parecía firme...

Then it gives the conclusion:

• ...habrá que cambiar la tuerca si el somier vuelve a hacer ruido.

So the order helps shape the flow of information, but the meaning stays basically the same.

Yes, somier is very common in Spain.

In other Spanish-speaking countries, people may use other words depending on the type of bed base or local vocabulary, such as terms closer to base, armazón, or other regional options. But for Spain, somier is perfectly normal and very natural in this sentence.