Jeg nådde hverken sonetaket eller topptaket.

It means neither ... nor.

In this sentence, hverken introduces the first item and eller introduces the second one:

• hverken sonetaket eller topptaket
• neither the zone cap nor the peak cap

A useful thing to remember is that eller normally means or, but after hverken it works like nor.

Because hverken ... eller already makes the sentence negative.

So:

• Jeg nådde hverken sonetaket eller topptaket = correct
• Jeg nådde ikke hverken sonetaket eller topptaket = normally wrong or at least nonstandard, because it creates an unnecessary double negation

In other words, hverken ... eller does the job that not ... either or neither ... nor does in English.

Nådde is the past tense of å nå, which means to reach.

The main forms are:

• å nå — infinitive
• når — present tense
• nådde — past tense
• har nådd — past participle / present perfect

So Jeg nådde ... means I reached ... in the past.

Because Norwegian usually writes compound nouns as single words.

So these are compounds:

• sonetak = sone
  • tak
• topptak = topp
  • tak

Then the definite ending is added:

• sonetaket
• topptaket

This is very normal in Norwegian. Where English often uses two words, Norwegian often uses one compound word.

The ending -et is the definite singular ending for many neuter nouns.

Here, the last part of both compounds is tak, and tak is a neuter noun. In Norwegian compounds, the last element decides the gender of the whole word.

So:

• et tak → taket
• et sonetak → sonetaket
• et topptak → topptaket

Even though sone and topp are different words, the whole compound follows the gender of tak.

Because the base word is topp, which already ends in double p.

When Norwegian makes compounds, it usually keeps the spelling of the first word:

• topp
  • tak → topptak
• topptak
  • -et → topptaket

So the double p is not extra; it comes from topp itself.

It often does mean roof, but in compounds it can also mean ceiling, cap, or upper limit.

So in words like these, tak is being used in the sense of a limit, not a literal roof.

That kind of meaning shift is common in Norwegian compounds.

Because hverken belongs to the pair hverken ... eller and introduces the first of the two linked items.

The structure is:

• Jeg — subject
• nådde — verb
• hverken sonetaket eller topptaket — object phrase

So the sentence is still following normal Norwegian word order. The whole object is simply a coordinated phrase meaning neither X nor Y.

Yes. In Bokmål, verken and hverken are both accepted spellings.

So you may also see:

• Jeg nådde verken sonetaket eller topptaket

The meaning is the same. Which one you use often depends on style, habit, or the form of Norwegian you are learning.

Yes, but hverken ... eller is the clearest and most natural way to express this exact idea.

Possible alternatives depend on context, for example:

• Jeg nådde ikke noen av delene — I reached neither of them / I reached neither one
• Jeg nådde ikke sonetaket, og heller ikke topptaket — a more expanded version

But if you want the neat direct structure neither ... nor, then Jeg nådde hverken sonetaket eller topptaket is exactly right.