De or het zolderberging?

The correct Dutch article is:

de zolderberging

Rule Words ending in -ing: almost always de. See the rule

How to use zolderberging

the zolderbergingde zolderberging
this zolderbergingdeze zolderberging
that zolderbergingdie zolderberging
our zolderbergingonze zolderberging
your zolderbergingjouw zolderberging
every zolderbergingelke zolderberging
which zolderberging?welke zolderberging?
a big zolderberging / the big zolderbergingeen grote zolderberging, de grote zolderberging