Dodatni radovi su skupi.

• dodatni = an adjective meaning additional, extra, or supplementary
• radovi = a plural noun meaning works, jobs, or tasks, depending on context
• su = the 3rd person plural form of biti (to be) = are
• skupi = an adjective meaning expensive or costly

So the structure is basically:

[adjective] + [noun] + [are] + [adjective]

= Additional works are expensive.

Radovi is the nominative plural form of rad.

• singular: rad = work, task, job, piece of work
• plural: radovi = works, jobs, tasks

In this sentence, the subject is plural, so Croatian uses the plural verb su (are), not je (is).

Compare:

• Dodatni rad je skup. = Additional work is expensive.
• Dodatni radovi su skupi. = Additional works / extra jobs are expensive.

Because the subject radovi is plural.

Croatian present tense of biti (to be) changes according to number:

• je = is for singular
• su = are for plural

So:

• Rad je skup. = The work is expensive.
• Radovi su skupi. = The works/jobs are expensive.

Because dodatni must agree with radovi.

In Croatian, adjectives agree with the noun in:

• gender
• number
• case

Here, radovi is:

• masculine
• plural
• nominative

So the adjective also takes the masculine plural nominative form:

• dodatni radovi = additional works/jobs

For comparison:

• dodatni rad = masculine singular
• dodatna knjiga = feminine singular
• dodatno pitanje = neuter singular

For the same reason: skupi agrees with radovi.

Since radovi is masculine plural nominative, the predicate adjective also appears in the matching form:

• radovi su skupi = masculine plural
• knjige su skupe = feminine plural
• pitanja su skupa = neuter plural

This is very common in Croatian. Adjectives after to be still agree with the subject.

Yes, literally it often means works, but the most natural English translation depends on context.

Radovi can refer to:

• construction works
• repair works
• extra jobs
• tasks
• pieces of work
• operations/work being done

So Dodatni radovi su skupi could mean:

• Additional work is expensive
• Extra work is expensive
• Additional works are expensive
• Extra jobs are expensive

In real life, this phrase is especially common in contexts like:

• building projects
• renovations
• invoices
• contracts
• repairs

There, dodatni radovi often means something like extra work beyond the original plan.

Because Croatian normally does not use articles like the or a/an.

English says:

• the additional works
• additional works
• the extra work

Croatian simply says:

• dodatni radovi

Whether it means additional works, the additional works, or some additional works depends on context.

That is one of the biggest differences for English speakers learning Croatian.

Not completely. Croatian word order is more flexible than English because the endings already show grammatical relationships.

The neutral, straightforward order here is:

Dodatni radovi su skupi.

But other orders are possible for emphasis, for example:

• Radovi su dodatni. = The works are additional / The works are extra
• Skupi su dodatni radovi. = emphasis on expensive
• Dodatni su radovi skupi. = less neutral, more marked

The most natural basic version is still:

Dodatni radovi su skupi.

Yes, but it sounds more emphatic.

• su is the normal unstressed form: are
• jesu is the stressed/full form

So:

• Dodatni radovi su skupi. = neutral statement
• Dodatni radovi jesu skupi. = Additional works really are expensive / stronger emphasis

In everyday speech, su is much more common unless you want contrast or emphasis.

A simple approximate pronunciation for an English speaker is:

doh-DAHT-nee RAH-doh-vee soo SKOO-pee

A few helpful points:

• d is always a clear d
• r in Croatian is rolled or tapped
• v is always pronounced, so radovi is not like English ra-doi
• u sounds like oo in food
• i sounds like ee in see

So:

• dodatni ≈ doh-DAHT-nee
• radovi ≈ RAH-doh-vee
• su ≈ soo
• skupi ≈ SKOO-pee

Here it is in the nominative plural, because it is the subject of the sentence.

The nominative is the form used for:

• the subject of a sentence
• dictionary headwords are usually given in singular nominative

So:

• dictionary singular: rad
• subject plural in this sentence: radovi

The adjectives dodatni and skupi are also in forms that match the nominative plural masculine subject.

Sometimes skup can mean expensive, and in some contexts forms of drag are more commonly used for dear in the emotional sense.

In this sentence, skupi clearly means expensive/costly, not dear/beloved.

So:

• skup auto = an expensive car
• radovi su skupi = the works are expensive

An English speaker should usually read skup/skupa/skupo as expensive unless context suggests otherwise.

The singular version would be:

Dodatni rad je skup.

Changes:

• radovi → rad
• su → je
• skupi → skup

That is because everything has to agree with the singular masculine noun rad.

So:

• plural: Dodatni radovi su skupi.
• singular: Dodatni rad je skup.

Yes, especially in practical or formal contexts, though the exact phrase may depend on the situation.

You may see similar expressions such as:

• dodatni radovi = additional works
• dodatni troškovi = additional costs
• dodatni posao = extra job/work
• dodatni zahvati = additional interventions/procedures

In construction, repairs, and billing, dodatni radovi is very natural and often refers to extra work that was not included originally.