Learn how to say Built Up correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word built-up:
1(of an area) densely covered by buildings:
he steered the stricken aircraft away from the built-up area
although the centre of Funchal is very built-up, there is still a lot of green land around the city
2increased in height by the addition of parts:
shoes with built-up heels
(of a feeling) increasing in intensity over a period of time: